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Pelka EZ, Davis BR, McDaniel J. Sourcebook update: using near-infrared spectroscopy to assess skeletal muscle oxygen uptake. ADVANCES IN PHYSIOLOGY EDUCATION 2024; 48:566-572. [PMID: 38779745 DOI: 10.1152/advan.00047.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Revised: 04/16/2024] [Accepted: 05/12/2024] [Indexed: 05/25/2024]
Abstract
Monitoring the metabolic cost or oxygen consumption associated with rest and exercise is crucial to understanding the impact of disease or physical training on the health of individuals. Traditionally, measuring the skeletal muscle oxygen cost associated with exercise/muscle contractions can be rather expensive or invasive (i.e., muscle biopsies). More recently, specific protocols designed around the use of near-infrared spectroscopy (NIRS) have been shown to provide a quick, noninvasive easy-to-use tool to measure skeletal muscle oxygen consumption ([Formula: see text]). However, the data and results from NIRS devices are often misunderstood. Thus the primary purpose of this sourcebook update is to provide several experimental protocols students can utilize to improve their understanding of NIRS technology, learn how to analyze results from NIRS devices, and better understand how muscle contraction intensity and type (isometric, concentric, or eccentric) influence the oxygen cost of muscle contractions.NEW & NOTEWORTHY Compared to traditional methods, near-infrared spectroscopy (NIRS) provides a relatively cheap and easy-to-use noninvasive technique to measure skeletal muscle oxygen uptake following exercise. This laboratory not only enables students to learn about the basics of NIRS and muscle energetics but also addresses more complex questions regarding skeletal muscle physiology.
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Affiliation(s)
- Edward Z Pelka
- Exercise Science and Exercise Physiology Program, Kent State University, Kent, Ohio, United States
| | - B Ryan Davis
- Exercise Science and Exercise Physiology Program, Kent State University, Kent, Ohio, United States
| | - John McDaniel
- Exercise Science and Exercise Physiology Program, Kent State University, Kent, Ohio, United States
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2
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Abbott EM, Stephens JD, Simha SN, Wood L, Nardelli P, Cope TC, Sawicki GS, Ting LH. Attenuation of muscle spindle firing with artificially increased series compliance during stretch of relaxed muscle. Exp Physiol 2024; 109:148-158. [PMID: 37856330 PMCID: PMC10841431 DOI: 10.1113/ep090872] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2022] [Accepted: 09/15/2023] [Indexed: 10/21/2023]
Abstract
Muscle spindles relay vital mechanosensory information for movement and posture, but muscle spindle feedback is coupled to skeletal motion by a compliant tendon. Little is known about the effects of tendon compliance on muscle spindle feedback during movement, and the complex firing of muscle spindles makes these effects difficult to predict. Our goal was to investigate changes in muscle spindle firing using added series elastic elements (SEEs) to mimic a more compliant tendon, and to characterize the accompanying changes in firing with respect to muscle-tendon unit (MTU) and muscle fascicle displacements (recorded via sonomicrometry). Sinusoidal, ramp-and-hold and triangular stretches were analysed to examine potential changes in muscle spindle instantaneous firing rates (IFRs) in locomotor- and perturbation-like stretches as well as serial history dependence. Added SEEs effectively reduced overall MTU stiffness and generally reduced muscle spindle firing rates, but the effect differed across stretch types. During sinusoidal stretches, peak and mean firing rates were not reduced and IFR was best-correlated with fascicle velocity. During ramp stretches, SEEs reduced the initial burst, dynamic and static responses of the spindle. Notably, IFR was negatively related to fascicle displacement during the hold phase. During triangular stretches, SEEs reduced the mean IFR during the first and second stretches, affecting the serial history dependence of mean IFR. Overall, these results demonstrate that tendon compliance may attenuate muscle spindle feedback during movement, but these changes cannot be fully explained by reduced muscle fascicle length or velocity, or MTU force.
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Affiliation(s)
- Emily M. Abbott
- Department of Biomedical EngineeringDuke UniversityDurhamNorth CarolinaUSA
| | - Jacob D. Stephens
- Coulter Department of Biomedical EngineeringEmory University and Georgia Institute of TechnologyAtlantaGeorgiaUSA
| | - Surabhi N. Simha
- Coulter Department of Biomedical EngineeringEmory University and Georgia Institute of TechnologyAtlantaGeorgiaUSA
| | - Leo Wood
- School of PhysicsGeorgia Institute of TechnologyAtlantaGeorgiaUSA
| | - Paul Nardelli
- School of Biological SciencesGeorgia Institute of TechnologyAtlantaGeorgiaUSA
| | - Timothy C. Cope
- Coulter Department of Biomedical EngineeringEmory University and Georgia Institute of TechnologyAtlantaGeorgiaUSA
- School of Biological SciencesGeorgia Institute of TechnologyAtlantaGeorgiaUSA
| | - Gregory S. Sawicki
- School of Biological SciencesGeorgia Institute of TechnologyAtlantaGeorgiaUSA
- Woodruff School of Mechanical EngineeringGeorgia Institute of TechnologyAtlantaGeorgiaUSA
| | - Lena H. Ting
- Coulter Department of Biomedical EngineeringEmory University and Georgia Institute of TechnologyAtlantaGeorgiaUSA
- Department of Rehabilitation MedicineEmory UniversityAtlantaGeorgiaUSA
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3
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Murakami Y, Nishida S, Kasahara K, Yoshida R, Hayakawa R, Nakamura M. Eccentric force and electromyogram comparison between the eccentric phase of the Nordic hamstring exercise and the razor hamstring curl. PLoS One 2023; 18:e0293938. [PMID: 38100489 PMCID: PMC10723670 DOI: 10.1371/journal.pone.0293938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Accepted: 10/23/2023] [Indexed: 12/17/2023] Open
Abstract
PURPOSE Nordic hamstring exercise (NHE) and razor hamstring curl (RHC) are usually performed to train hamstring eccentric contraction strength. However, it is unclear whether there are differences in the intensity of the two methods and the amount of loading on each muscle. Therefore, this study was conducted using peak eccentric force and each muscle surface electromyogram (s-EMG) to provide useful information to decide whether NHE or RHC should be prescribed for training and rehabilitation. METHODS s-EMG electrodes were placed in the medial gastrocnemius, lateral gastrocnemius, biceps femoris, semitendinosus, gluteus maximus, and erector spinae of the dominant leg of the fifteen healthy male university students with exercise habits. Maximum voluntary isometric contractions of 3 seconds were performed on each muscle followed by NHE and RHC in random order. The outcome variables included peak eccentric force and s-EMG of each muscle calculated by means amplitude during the NHE and RHC. RESULTS Peak eccentric force was significantly higher in RHC than in NHE (p = 0.001, r = 0.73). However, NHE was significantly higher in s-EMG of semitendinosus (p = 0.04, r = -0.52) than RHC. However, there were no significant differences in EMG of the medial gastrocnemius (p = 0.202, r = -0.34), lateral gastrocnemius (p = 0.496, r = 0.18), biceps femoris (p = 0.061, r = -0.48), gluteus maximus (p = 0.112, r = -0.41), erector spinae (p = 0.45, r = 0.20) between NHE and RHC. CONCLUSIONS For NHE and RHC, the peak eccentric force exerted during the exercise was significantly higher for RHC, and the s-EMG of semitendinosus was significantly higher for NHE.
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Affiliation(s)
- Yuta Murakami
- Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare, Niigata, Japan
| | - Satoru Nishida
- Faculty of Sports and Health Science, Ryutsu Keizai University, Ibaraki, Japan
| | - Kaziki Kasahara
- Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare, Niigata, Japan
| | - Riku Yoshida
- Department of Rehabilitation, Medical Corporation, Maniwa Orthopedic Clinic, Niigata, Japan
| | - Ryo Hayakawa
- Department of Rehabilitation, Medical Corporation Sansuikai, Kitachiba Orthopedic, Makuhari Clinic, Chiba, Japan
| | - Masatoshi Nakamura
- Faculty of Rehabilitation Sciences, Nishi Kyushu University, Saga, Japan
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Kalkhoven JT, Lukauskis-Carvajal M, Sides DL, McLean BD, Watsford ML. A Conceptual Exploration of Hamstring Muscle-Tendon Functioning during the Late-Swing Phase of Sprinting: The Importance of Evidence-Based Hamstring Training Frameworks. Sports Med 2023; 53:2321-2346. [PMID: 37668895 PMCID: PMC10687166 DOI: 10.1007/s40279-023-01904-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/01/2023] [Indexed: 09/06/2023]
Abstract
An eccentrically lengthening, energy-absorbing, brake-driven model of hamstring function during the late-swing phase of sprinting has been widely touted within the existing literature. In contrast, an isometrically contracting, spring-driven model of hamstring function has recently been proposed. This theory has gained substantial traction within the applied sporting world, influencing understandings of hamstring function while sprinting, as well as the development and adoption of certain types of hamstring-specific exercises. Across the animal kingdom, both spring- and motor-driven muscle-tendon unit (MTU) functioning are frequently observed, with both models of locomotive functioning commonly utilising some degree of active muscle lengthening to draw upon force enhancement mechanisms. However, a method to accurately assess hamstring muscle-tendon functioning when sprinting does not exist. Accordingly, the aims of this review article are three-fold: (1) to comprehensively explore current terminology, theories and models surrounding muscle-tendon functioning during locomotion, (2) to relate these models to potential hamstring function when sprinting by examining a variety of hamstring-specific research and (3) to highlight the importance of developing and utilising evidence-based frameworks to guide hamstring training in athletes required to sprint. Due to the intensity of movement, large musculotendinous stretches and high mechanical loads experienced in the hamstrings when sprinting, it is anticipated that the hamstring MTUs adopt a model of functioning that has some reliance upon active muscle lengthening and muscle actuators during this particular task. However, each individual hamstring MTU is expected to adopt various combinations of spring-, brake- and motor-driven functioning when sprinting, in accordance with their architectural arrangement and activation patterns. Muscle function is intricate and dependent upon complex interactions between musculoskeletal kinematics and kinetics, muscle activation patterns and the neuromechanical regulation of tensions and stiffness, and loads applied by the environment, among other important variables. Accordingly, hamstring function when sprinting is anticipated to be unique to this particular activity. It is therefore proposed that the adoption of hamstring-specific exercises should not be founded on unvalidated claims of replicating hamstring function when sprinting, as has been suggested in the literature. Adaptive benefits may potentially be derived from a range of hamstring-specific exercises that vary in the stimuli they provide. Therefore, a more rigorous approach is to select hamstring-specific exercises based on thoroughly constructed evidence-based frameworks surrounding the specific stimulus provided by the exercise, the accompanying adaptations elicited by the exercise, and the effects of these adaptations on hamstring functioning and injury risk mitigation when sprinting.
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Affiliation(s)
- Judd T Kalkhoven
- Sport & Exercise Science Discipline Group, Faculty of Health, Human Performance Research Centre, University of Technology Sydney, Moore Park Precinct, PO Box 123, Broadway, NSW, 2007, Australia.
| | - Mathias Lukauskis-Carvajal
- Sport & Exercise Science Discipline Group, Faculty of Health, Human Performance Research Centre, University of Technology Sydney, Moore Park Precinct, PO Box 123, Broadway, NSW, 2007, Australia
- SpeedLab, Cali, Colombia
| | - Deborah L Sides
- UK Sports Institute, Manchester Institute of Health and Performance, Manchester, UK
| | - Blake D McLean
- Sport & Exercise Science Discipline Group, Faculty of Health, Human Performance Research Centre, University of Technology Sydney, Moore Park Precinct, PO Box 123, Broadway, NSW, 2007, Australia
| | - Mark L Watsford
- Sport & Exercise Science Discipline Group, Faculty of Health, Human Performance Research Centre, University of Technology Sydney, Moore Park Precinct, PO Box 123, Broadway, NSW, 2007, Australia
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Gasser B, Niederseer D, Frey WO, Catuogno S, Flück M. ACE-I/D Allele Modulates Improvements of Cardiorespiratory Function and Muscle Performance with Interval-Type Exercise. Genes (Basel) 2023; 14:1100. [PMID: 37239460 PMCID: PMC10218657 DOI: 10.3390/genes14051100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 05/15/2023] [Accepted: 05/16/2023] [Indexed: 05/28/2023] Open
Abstract
Background: The prominent insertion/deletion polymorphism in the gene for the major modulator of tissue perfusion, angiotensin-converting enzyme (ACE-I/D) is associated with variability in adjustments in cardiac and skeletal muscle performance with standard forms of endurance and strength type training. Here, we tested whether the ACE-I/D genotype would be associated with variability in the effects of interval-type training on peak and aerobic performance of peripheral muscle and cardio-vasculature and post-exercise recovery. Methods: Nine healthy subjects (39.0 ± 14.7 years of age; 64.6 ± 16.1 kg, 173.6 ± 9.9) completed eight weeks of interval training on a soft robotic device based on repeated sets of a pedaling exercise at a matched intensity relative to their peak aerobic power output. Prior to and post-training, peak anaerobic and aerobic power output was assessed, mechanical work and metabolic stress (oxygen saturation and hemoglobin concentrations of Musculus vastus lateralis (VAS) and Musculus gastrocnemius (GAS), blood lactate and factors setting cardiac output such as heart rate, systolic and diastolic blood pressure were monitored during ramp-incremental exercise and interval exercise with the calculation of areas under the curve (AUC), which were put in relation to the produced muscle work. Genotyping was performed based on I- and D-allele-specific polymerase chain reactions on genomic DNA from mucosal swaps. The significance of interaction effects between training and ACE I-allele on absolute and work-related values was assessed with repeated measures ANOVA. Results: Subjects delivered 87% more muscle work/power, 106% more cardiac output, and muscles experienced ~72% more of a deficit in oxygen saturation and a ~35% higher passage of total hemoglobin during single interval exercise after the eight weeks of training. Interval training affected aspects of skeletal muscle metabolism and performance, whose variability was associated with the ACE I-allele. This concerned the economically favorable alterations in the work-related AUC for the deficit of SmO2 in the VAS and GAS muscles during the ramp exercise for the I-allele carriers and opposing deteriorations in non-carriers. Conversely, oxygen saturation in the VAS and GAS at rest and during interval exercise was selectively improved after training for the non-carriers of the I-allele when the AUC of tHb per work during interval exercise deteriorated in the carriers. Training also improved aerobic peak power output by 4% in the carriers but not the non-carriers (p = 0.772) of the ACE I-allele while reducing negative peak power (-27.0%) to a lesser extent in the ACE I-allele carriers than the non-carriers. Variability in cardiac parameters (i.e., the AUC of heart rate and glucose during ramp exercise, was similar to the time to recovery of maximal tHb in both muscles after cessation of ramp exercise, only associated with the ACE I-allele but not training per se. Diastolic blood pressure and cardiac output during recovery from exhaustive ramp exercise demonstrated a trend for training-associated differences in association with the ACE I-allele. Discussion: The exercise-type dependent manifestation of antidromic adjustments in leg muscle perfusion and associated local aerobic metabolism between carriers and non-carriers of the ACE I-allele with the interval-training highlight that non-carriers of the I-allele do not present an essential handicap to improve perfusion-related aerobic muscle metabolism but that the manifestation of responsiveness depends on the produced work. Conclusions: The deployed interval-type of exercise produced ACE I-allele-related differences in the alterations of negative anaerobic performance and perfusion-related aerobic muscle metabolism, which manifestation is exercise specific. The training-invariant ACE I-allele-associated differences in heart rate and blood glucose concentration emphasize that the repeated impact of the interval stimulus, despite a near doubling of the initial metabolic load, was insufficient to overturn ACE-related genetic influences on cardiovascular function.
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Affiliation(s)
- Benedikt Gasser
- Departement für Bewegung und Sport, Universität Basel, CH-4052 Basel, Switzerland
| | - David Niederseer
- Department of Cardiology, University Hospital Zurich, University of Zurich, CH-8008 Zurich, Switzerland;
| | - Walter O. Frey
- Swiss Olympic Medical Center, Balgrist University Hospital, CH-8008 Zurich, Switzerland; (W.O.F.); (S.C.)
| | - Silvio Catuogno
- Swiss Olympic Medical Center, Balgrist University Hospital, CH-8008 Zurich, Switzerland; (W.O.F.); (S.C.)
| | - Martin Flück
- Laboratory for Muscle Plasticity, University of Zurich, Balgrist Campus, CH-8008 Zurich, Switzerland
- Department of Medicine, University of Fribourg, CH-1700 Fribourg, Switzerland
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6
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Holt NC, Mayfield DL. Muscle-tendon unit design and tuning for power enhancement, power attenuation, and reduction of metabolic cost. J Biomech 2023; 153:111585. [PMID: 37126884 PMCID: PMC10949972 DOI: 10.1016/j.jbiomech.2023.111585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Accepted: 04/06/2023] [Indexed: 05/03/2023]
Abstract
The contractile elements in skeletal muscle fibers operate in series with elastic elements, tendons and potentially aponeuroses, in muscle-tendon units (MTUs). Elastic strain energy (ESE), arising from either work done by muscle fibers or the energy of the body, can be stored in these series elastic elements (SEEs). MTUs vary considerably in their design in terms of the relative lengths and stiffnesses of the muscle fibers and SEEs, and the force and work generating capacities of the muscle fibers. However, within an MTU it is thought that contractile and series elastic elements can be matched or tuned to maximize ESE storage. The use of ESE is thought to improve locomotor performance by enhancing contractile element power during activities such as jumping, attenuating contractile element power during activities such as landing, and reducing the metabolic cost of movement during steady-state activities such as walking and running. The effectiveness of MTUs in these potential roles is contingent on factors such as the source of mechanical energy, the control of the flow of energy, and characteristics of SEE recoil. Hence, we suggest that MTUs specialized for ESE storage may vary considerably in the structural, mechanical, and physiological properties of their components depending on their functional role and required versatility.
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Affiliation(s)
- N C Holt
- Department of Evolution, Ecology and Organismal Biology, University of California Riverside, 900 University Avenue, Riverside, CA 92521, USA.
| | - D L Mayfield
- Department of Evolution, Ecology and Organismal Biology, University of California Riverside, 900 University Avenue, Riverside, CA 92521, USA
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7
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Eccentric muscle contractions: from single muscle fibre to whole muscle mechanics. Pflugers Arch 2023; 475:421-435. [PMID: 36790515 PMCID: PMC10011336 DOI: 10.1007/s00424-023-02794-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 01/24/2023] [Accepted: 02/01/2023] [Indexed: 02/16/2023]
Abstract
Eccentric muscle loading encompasses several unique features compared to other types of contractions. These features include increased force, work, and performance at decreased oxygen consumption, reduced metabolic cost, improved energy efficiency, as well as decreased muscle activity. This review summarises explanatory approaches to long-standing questions in terms of muscular contraction dynamics and molecular and cellular mechanisms underlying eccentric muscle loading. Moreover, this article intends to underscore the functional link between sarcomeric components, emphasising the fundamental role of titin in skeletal muscle. The giant filament titin reveals versatile functions ranging from sarcomere organisation and maintenance, providing passive tension and elasticity, and operates as a mechanosensory and signalling platform. Structurally, titin consists of a viscoelastic spring segment that allows activation-dependent coupling to actin. This titin-actin interaction can explain linear force increases in active lengthening experiments in biological systems. A three-filament model of skeletal muscle force production (mediated by titin) is supposed to overcome significant deviations between experimental observations and predictions by the classic sliding-filament and cross-bridge theories. Taken together, this review intends to contribute to a more detailed understanding of overall muscle behaviour and force generation-from a microscopic sarcomere level to a macroscopic multi-joint muscle level-impacting muscle modelling, the understanding of muscle function, and disease.
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8
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Jeong S, Nishikawa K. The force response of muscles to activation and length perturbations depends on length history. J Exp Biol 2023; 226:286982. [PMID: 36655760 DOI: 10.1242/jeb.243991] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 01/13/2023] [Indexed: 01/20/2023]
Abstract
Recent studies have demonstrated that muscle force is not determined solely by activation under dynamic conditions, and that length history has an important role in determining dynamic muscle force. Yet, the mechanisms for how muscle force is produced under dynamic conditions remain unclear. To explore this, we investigated the effects of muscle stiffness, activation and length perturbations on muscle force. First, submaximal isometric contraction was established for whole soleus muscles. Next, the muscles were actively shortened at three velocities. During active shortening, we measured muscle stiffness at optimal muscle length (L0) and the force response to time-varying activation and length perturbations. We found that muscle stiffness increased with activation but decreased as shortening velocity increased. The slope of the relationship between maximum force and activation amplitude differed significantly among shortening velocities. Also, the intercept and slope of the relationship between length perturbation amplitude and maximum force decreased with shortening velocity. As shortening velocities were related to muscle stiffness, the results suggest that length history determines muscle stiffness and the history-dependent muscle stiffness influences the contribution of activation and length perturbations to muscle force. A two-parameter viscoelastic model including a linear spring and a linear damper in parallel with measured stiffness predicted history-dependent muscle force with high accuracy. The results and simulations support the hypothesis that muscle force under dynamic conditions can be accurately predicted as the force response of a history-dependent viscoelastic material to length perturbations.
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Affiliation(s)
- Siwoo Jeong
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011-5640, USA
| | - Kiisa Nishikawa
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011-5640, USA
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9
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Effects of shortening velocity on the stiffness to force ratio during isometric force redevelopment suggest mechanisms of residual force depression. Sci Rep 2023; 13:948. [PMID: 36653512 PMCID: PMC9849346 DOI: 10.1038/s41598-023-28236-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Accepted: 01/16/2023] [Indexed: 01/19/2023] Open
Abstract
Although the phenomenon of residual force depression has been known for decades, the mechanisms remain elusive. In the present study, we investigated mechanisms of residual force depression by measuring the stiffness to force ratio during force redevelopment after shortening at different velocities. The results showed that the slope of the relationship between muscle stiffness and force decreased with decreasing shortening velocity, and the y-intercept increased with decreasing shortening velocity. The differing slopes and y-intercepts indicate that the stiffness to force ratio during isometric force redevelopment depends on the active shortening velocity at a given muscle length and activation level. The greater stiffness to force ratio after active shortening can potentially be explained by weakly-bound cross bridges in the new overlap zone. However, weakly-bound cross bridges are insufficient to explain the reduced slope at the slowest shortening velocity because the reduced velocity should increase the proportion of weakly- to strongly-bound cross bridges, thereby increasing the slope. In addition, if actin distortion caused by active shortening recovers during the force redevelopment period, then the resulting slope should be similar to the non-linear slope of force redevelopment over time. Alternatively, we suggest that a tunable elastic element, such as titin, could potentially explain the results.
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10
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Hirono T, Kunugi S, Yoshimura A, Holobar A, Watanabe K. Acute changes in motor unit discharge property after concentric versus eccentric contraction exercise in knee extensor. J Electromyogr Kinesiol 2022; 67:102704. [PMID: 36137408 DOI: 10.1016/j.jelekin.2022.102704] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Revised: 08/26/2022] [Accepted: 09/12/2022] [Indexed: 12/14/2022] Open
Abstract
This study aimed to investigate the motor unit firing property immediately after concentric or eccentric contraction exercise. Eighteen healthy men performed repetitive maximal isokinetic knee extension exercises with only concentric or eccentric contraction until they exerted less than 80% of the baseline strength. Before and after the fatiguing exercise, high-density surface electromyography of the vastus lateralis was recorded during submaximal ramp-up isometric contraction and individual motor units were identified. Only motor units that could be tracked before and after exercise were analyzed. Muscle cross-sectional area of the vastus lateralis was measured using ultrasound, and electrically evoked torque was recorded before and after the exercise. Sixty-five and fifty-three motor units were analyzed before and after the concentric and eccentric contractions, respectively. The results showed that motor units with moderate to high recruitment thresholds significantly decreased recruitment thresholds under both conditions, and the motor unit discharge rates significantly increased after concentric contraction compared to eccentric contraction. A greater muscle cross-sectional area was observed with concentric contraction. The evoked torque was significantly decreased under both conditions, but no difference between the conditions. These results suggest that fatiguing exercise with concentric contraction contributes to greater neural input to muscles and metabolic responses than eccentric contraction.
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Affiliation(s)
- Tetsuya Hirono
- Laboratory of Neuromuscular Biomechanics, School of Health and Sport Science, Chukyo University, 101 Tokodachi, Kaizu-cho, Toyota, Aichi 470-0393, Japan; Research Fellow of Japan Society for the Promotion of Science, Kojimachi, Chiyoda-ku, Tokyo 102-0083, Japan.
| | - Shun Kunugi
- Laboratory of Neuromuscular Biomechanics, School of Health and Sport Science, Chukyo University, 101 Tokodachi, Kaizu-cho, Toyota, Aichi 470-0393, Japan; Center for General Education, Aichi Institute of Technology, 1247 Yachigusa, Yakusa-cho, Toyota-shi, Aichi 470-0392, Japan
| | - Akane Yoshimura
- Laboratory of Neuromuscular Biomechanics, School of Health and Sport Science, Chukyo University, 101 Tokodachi, Kaizu-cho, Toyota, Aichi 470-0393, Japan; Faculty of Education and Integrated Arts and Sciences, Waseda University, 1-6-1, Nishiwaseda, Shinjuku-ku, Tokyo 169-8050, Japan
| | - Aleš Holobar
- Faculty of Electrical Engineering and Computer Science, University of Maribor, Koroška cesta 46, SI-2000 Maribor, Slovenia
| | - Kohei Watanabe
- Laboratory of Neuromuscular Biomechanics, School of Health and Sport Science, Chukyo University, 101 Tokodachi, Kaizu-cho, Toyota, Aichi 470-0393, Japan
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11
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Shi J, Watanabe D, Wada M. Eccentric muscle contraction potentiates titin stiffness-related contractile properties in rat fast-twitch muscles. J Appl Physiol (1985) 2022; 133:710-720. [PMID: 35981734 DOI: 10.1152/japplphysiol.00327.2022] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This study was conducted to examine the effects of an acute bout of eccentric muscle contraction (ECC) on titin stiffness-related contractile properties in rat fast-twitch skeletal muscles. Intact gastrocnemius muscles were electrically stimulated in situ to undergo 200-repeated ECCs. Immediately after cessation of the stimulation, the superficial regions of the muscles were dissected and subjected to biochemical and skinned fiber analyses. Small heat shock protein αB-crystallin in the muscle fraction enriched for myofibrillar proteins was increased by ECC. ECC resulted in an increase in the titin-based passive force. Protein kinase A-treatment decreased the passive force only in ECC-subjected but not in rested fibers. ECC decreased the maximum Ca2+-activated force at a sarcomere length (SL) of 2.4 μm and had no effect on myofibrillar-Ca2+ sensitivity at 2.6-μm SL. In both rested and ECC-subjected fibers, these two variables were higher at 3.0-μm SL than at 2.4- or 2.6-μm SL. The differences in the two variables between the short and long SLs were greater in ECC-subjected than in rested fibers. These results indicate that an acute bout of ECC potentiates titin-based passive force, maximum active force at long SLs, and length-dependent activation and suggest that this potentiation may resist muscle fatigue in the muscles of the exercising body.
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Affiliation(s)
- Jiayu Shi
- Graduate School of Integrated Arts and Sciences, Hiroshima University, Hiroshima, Japan
| | - Daiki Watanabe
- Graduate School of Humanities and Social Sciences, Hiroshima University, Hiroshima, Japan
| | - Masanobu Wada
- Graduate School of Integrated Arts and Sciences, Hiroshima University, Hiroshima, Japan.,Graduate School of Humanities and Social Sciences, Hiroshima University, Hiroshima, Japan
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12
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Mishra D, Nishikawa KC. Residual force enhancement is reduced in permeabilized fiber bundles from mdm muscles. J Exp Biol 2022; 225:275519. [PMID: 35514253 DOI: 10.1242/jeb.243732] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Accepted: 04/28/2022] [Indexed: 11/20/2022]
Abstract
Residual force enhancement (RFE) is the increase in steady-state force after active stretch relative to the force during isometric contraction at the same final length. The mdm mutation in mice, characterized by a small deletion in N2A titin, has been proposed to prevent N2A titin-actin interactions so that active mdm muscles are more compliant than WT. This decrease in active muscle stiffness is associated with reduced RFE. We investigated RFE in permeabilized soleus (SOL) and extensor digitorum longus (EDL) fiber bundles from wild type and mdm mice. On each fiber bundle, we performed active and passive stretches from an average sarcomere length of 2.6 - 3.0 µm at a slow rate of 0.04 µm/s, as well as isometric contractions at the initial and final lengths. One-way ANOVA showed that SOL and EDL fiber bundles from mdm mice exhibited significantly lower RFE than WT (P<0.0001). This result is consistent with previous observations in single myofibrils and intact muscles. However, it contradicts the results from a previous study which appeared to show that compensatory mechanisms could restore titin force enhancement in single fibers from mdm psoas. We suggest that residual force enhancement measured previously in mdm single fibers was an artifact of the high variability in passive tension found in degenerating fibers, which begins after ∼24 days of age. The results are consistent with the hypothesis that RFE is reduced in mdm skeletal muscles due to impaired Ca2+ dependent titin-actin interactions resulting from the small deletion in N2A titin.
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Affiliation(s)
- Dhruv Mishra
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, USA
| | - Kiisa C Nishikawa
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, USA
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13
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Single skeletal muscle fiber mechanical properties: a muscle quality biomarker of human aging. Eur J Appl Physiol 2022; 122:1383-1395. [DOI: 10.1007/s00421-022-04924-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Accepted: 02/23/2022] [Indexed: 12/25/2022]
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Frischholz J, Raiteri BJ, Cresswell AG, Hahn D. Corticospinal excitability remains unchanged in the presence of residual force enhancement and does not contribute to increased torque production. PeerJ 2022; 10:e12729. [PMID: 35036100 PMCID: PMC8743010 DOI: 10.7717/peerj.12729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 12/10/2021] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Following stretch of an active muscle, muscle force is enhanced, which is known as residual force enhancement (rFE). As earlier studies found apparent corticospinal excitability modulations in the presence of rFE, this study aimed to test whether corticospinal excitability modulations contribute to rFE. METHODS Fourteen participants performed submaximal plantar flexion stretch-hold and fixed-end contractions at 30% of their maximal voluntary soleus muscle activity in a dynamometer. During the steady state of the contractions, participants either received subthreshold or suprathreshold transcranial magnetic stimulation (TMS) of their motor cortex, while triceps surae muscle responses to stimulation were obtained via electromyography (EMG), and net ankle joint torque was recorded. B-mode ultrasound imaging was used to confirm muscle fascicle stretch during stretch-hold contractions in a subset of participants. RESULTS Following stretch of the plantar flexors, an average rFE of 7% and 11% was observed for contractions with subthreshold and suprathreshold TMS, respectively. 41-46 ms following subthreshold TMS, triceps surae muscle activity was suppressed by 19-25%, but suppression was not significantly different between stretch-hold and fixed-end contractions. Similarly, the reduction in plantar flexion torque following subthreshold TMS was not significantly different between contraction conditions. Motor evoked potentials, silent periods and superimposed twitches following suprathreshold TMS were also not significantly different between contraction conditions. DISCUSSION As TMS of the motor cortex did not result in any differences between stretch-hold and fixed-end contractions, we conclude that rFE is not linked to changes in corticospinal excitability.
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Affiliation(s)
- Jasmin Frischholz
- Human Movement Science, Faculty of Sport Science, Ruhr University Bochum, Bochum, Germany
| | - Brent J. Raiteri
- Human Movement Science, Faculty of Sport Science, Ruhr University Bochum, Bochum, Germany
| | - Andrew G. Cresswell
- School of Human Movement and Nutrition Sciences, University of Queensland, Brisbane, Australia
| | - Daniel Hahn
- Human Movement Science, Faculty of Sport Science, Ruhr University Bochum, Bochum, Germany,School of Human Movement and Nutrition Sciences, University of Queensland, Brisbane, Australia
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Harris-Love MO, Gollie JM, Keogh JWL. Eccentric Exercise: Adaptations and Applications for Health and Performance. J Funct Morphol Kinesiol 2021; 6:96. [PMID: 34842737 PMCID: PMC8628948 DOI: 10.3390/jfmk6040096] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Revised: 11/19/2021] [Accepted: 11/19/2021] [Indexed: 12/12/2022] Open
Abstract
The goals of this narrative review are to provide a brief overview of the muscle and tendon adaptations to eccentric resistance exercise and address the applications of this form of training to aid rehabilitative interventions and enhance sports performance. This work is centered on the author contributions to the Special Issue entitled "Eccentric Exercise: Adaptations and Applications for Health and Performance". The major themes from the contributing authors include the need to place greater attention on eccentric exercise mode selection based on training goals and individual fitness level, optimal approaches to implementing eccentric resistance exercise for therapeutic purposes, factors that affect the use of eccentric exercise across the lifespan, and general recommendations to integrate eccentric exercise in athletic training regimens. The authors propose that movement velocity and the absorption or recovery of kinetic energy are critical components of eccentric exercise programming. Regarding the therapeutic use of eccentric resistance training, patient-level factors regarding condition severity, fitness level, and stage of rehabilitation should govern the plan of care. In athletic populations, use of eccentric exercise may improve movement competency and promote improved safety and performance of sport-specific tasks. Eccentric resistance training is a viable option for youth, young adults, and older adults when the exercise prescription appropriately addresses program goals, exercise tolerability, and compliance. Despite the benefits of eccentric exercise, several key questions remain unanswered regarding its application underscoring the need for further investigation.
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Affiliation(s)
- Michael O. Harris-Love
- Physical Therapy Program, Department of Physical Medicine and Rehabilitation, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
- Geriatric Research Education and Clinical Center, VA Eastern Colorado Healthcare System, Aurora, CO 80045, USA
- Muscle Morphology, Mechanics, and Performance Laboratory, Geriatrics Service, Veterans Affairs Medical Center, Washington, DC 20422, USA;
| | - Jared M. Gollie
- Muscle Morphology, Mechanics, and Performance Laboratory, Geriatrics Service, Veterans Affairs Medical Center, Washington, DC 20422, USA;
- Department of Health, Human Function, and Rehabilitation Sciences, School of Medicine & Health Sciences, George Washington University, Washington, DC 20052, USA
| | - Justin W. L. Keogh
- Faculty of Health Sciences and Medicine, Bond University, Robina, QLD 4226, Australia;
- Sports Performance Research Centre New Zealand, Auckland University of Technology, Auckland 1010, New Zealand
- Cluster for Health Improvement, Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Sunshine Coast, QLD 4556, Australia
- Kasturba Medical College, Mangalore, Manipal Academy of Higher Education, Manipal 576104, Karnataka, India
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Nishikawa K, Huck TG. Muscle as a tunable material: implications for achieving muscle-like function in robotic prosthetic devices. J Exp Biol 2021; 224:272387. [PMID: 34605903 DOI: 10.1242/jeb.225086] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
An ideal prosthesis should perform as well as or better than the missing limb it was designed to replace. Although this ideal is currently unattainable, recent advances in design have significantly improved the function of prosthetic devices. For the lower extremity, both passive prostheses (which provide no added power) and active prostheses (which add propulsive power) aim to emulate the dynamic function of the ankle joint, whose adaptive, time-varying resistance to applied forces is essential for walking and running. Passive prostheses fail to normalize energetics because they lack variable ankle impedance that is actively controlled within each gait cycle. By contrast, robotic prostheses can normalize energetics for some users under some conditions. However, the problem of adaptive and versatile control remains a significant issue. Current prosthesis-control algorithms fail to adapt to changes in gait required for walking on level ground at different speeds or on ramps and stairs. A new paradigm of 'muscle as a tunable material' versus 'muscle as a motor' offers insights into the adaptability and versatility of biological muscles, which may provide inspiration for prosthesis design and control. In this new paradigm, neural activation tunes muscle stiffness and damping, adapting the response to applied forces rather than instructing the timing and amplitude of muscle force. A mechanistic understanding of muscle function is incomplete and would benefit from collaboration between biologists and engineers. An improved understanding of the adaptability of muscle may yield better models as well as inspiration for developing prostheses that equal or surpass the functional capabilities of biological limbs across a wide range of conditions.
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Affiliation(s)
- Kiisa Nishikawa
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011-5640, USA
| | - Thomas G Huck
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011-5640, USA
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17
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Jeon W, Whitall J, Griffin L, Westlake KP. Trunk kinematics and muscle activation patterns during stand-to-sit movement and the relationship with postural stability in aging. Gait Posture 2021; 86:292-298. [PMID: 33838526 DOI: 10.1016/j.gaitpost.2021.03.025] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 02/25/2021] [Accepted: 03/17/2021] [Indexed: 02/02/2023]
Abstract
BACKGROUND Stand-to-sit (StandTS) movement is an important functional activity that can be challenging for older adults due to age-related changes in neuromotor control. Although trunk flexion, eccentric contraction of the rectus femoris (RF), and coordination of RF and biceps femoris (BF) muscles are important to the StandTS task, the effects of aging on these and related outcomes are not well studied. RESEARCH QUESTION What are the age-related differences in trunk flexion, lower extremity muscle activation patterns, and postural stability during a StandTS task and what is the relationship between these variables? METHODS Ten younger and ten older healthy adults performed three StandTS trials at self-selected speeds. Outcomes included peak amplitude, peak timing, burst duration, and onset latency of electromyography (EMG) activity of the RF and BF muscles, trunk flexion angle and angular velocity, whole body center of mass (CoM) displacement, center of pressure (CoP) velocity, and ground reaction force (GRF). RESULTS There were no age-related differences in weight-bearing symmetry, StandTS and trunk flexion angular velocity, or BF activity. In both groups, EMG peak timing of RF was preceded by BF. Compared to younger adults, older adults demonstrated shorter RF EMG burst duration, reduced trunk flexion, and reduced stability as indicated by the longer duration in which CoM was maintained beyond the posterior limit of base of support (BoS), greater mean anterior-posterior CoP velocity and larger standard deviation of CoM vertical acceleration during StandTS with smaller vertical GRF immediately prior to StandTS termination. Trunk flexion angle and RF EMG burst duration correlated with stability as measured by the duration in which the CoM stayed within the BoS. SIGNIFICANCE Decreased trunk flexion and impaired eccentric control of the RF are associated with StandTS instability in aging and suggest the importance of including StandTS training as a part of a comprehensive balance intervention.
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Affiliation(s)
- Woohyoung Jeon
- Department of Kinesiology and Health Education, University of Texas at Austin, Austin, TX, United States; University of Maryland School of Medicine, Department of Physical Therapy & Rehabilitation Science, Baltimore, MD, United States.
| | - Jill Whitall
- University of Maryland School of Medicine, Department of Physical Therapy & Rehabilitation Science, Baltimore, MD, United States.
| | - Lisa Griffin
- Department of Kinesiology and Health Education, University of Texas at Austin, Austin, TX, United States.
| | - Kelly P Westlake
- University of Maryland School of Medicine, Department of Physical Therapy & Rehabilitation Science, Baltimore, MD, 21201, United States.
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Hessel AL, Monroy JA, Nishikawa KC. Non-cross Bridge Viscoelastic Elements Contribute to Muscle Force and Work During Stretch-Shortening Cycles: Evidence From Whole Muscles and Permeabilized Fibers. Front Physiol 2021; 12:648019. [PMID: 33854441 PMCID: PMC8039322 DOI: 10.3389/fphys.2021.648019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Accepted: 03/08/2021] [Indexed: 12/27/2022] Open
Abstract
The sliding filament-swinging cross bridge theory of skeletal muscle contraction provides a reasonable description of muscle properties during isometric contractions at or near maximum isometric force. However, it fails to predict muscle force during dynamic length changes, implying that the model is not complete. Mounting evidence suggests that, along with cross bridges, a Ca2+-sensitive viscoelastic element, likely the titin protein, contributes to muscle force and work. The purpose of this study was to develop a multi-level approach deploying stretch-shortening cycles (SSCs) to test the hypothesis that, along with cross bridges, Ca2+-sensitive viscoelastic elements in sarcomeres contribute to force and work. Using whole soleus muscles from wild type and mdm mice, which carry a small deletion in the N2A region of titin, we measured the activation- and phase-dependence of enhanced force and work during SSCs with and without doublet stimuli. In wild type muscles, a doublet stimulus led to an increase in peak force and work per cycle, with the largest effects occurring for stimulation during the lengthening phase of SSCs. In contrast, mdm muscles showed neither doublet potentiation features, nor phase-dependence of activation. To further distinguish the contributions of cross bridge and non-cross bridge elements, we performed SSCs on permeabilized psoas fiber bundles activated to different levels using either [Ca2+] or [Ca2+] plus the myosin inhibitor 2,3-butanedione monoxime (BDM). Across activation levels ranging from 15 to 100% of maximum isometric force, peak force, and work per cycle were enhanced for fibers in [Ca2+] plus BDM compared to [Ca2+] alone at a corresponding activation level, suggesting a contribution from Ca2+-sensitive, non-cross bridge, viscoelastic elements. Taken together, our results suggest that a tunable viscoelastic element such as titin contributes to: (1) persistence of force at low [Ca2+] in doublet potentiation; (2) phase- and length-dependence of doublet potentiation observed in wild type muscles and the absence of these effects in mdm muscles; and (3) increased peak force and work per cycle in SSCs. We conclude that non-cross bridge viscoelastic elements, likely titin, contribute substantially to muscle force and work, as well as the phase-dependence of these quantities, during dynamic length changes.
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Affiliation(s)
- Anthony L Hessel
- Institute of Physiology II, University of Muenster, Muenster, Germany
| | - Jenna A Monroy
- W.M. Keck Science Department, Claremont Colleges, Claremont, CA, United States
| | - Kiisa C Nishikawa
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, United States
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Bishop PJ, Falisse A, De Groote F, Hutchinson JR. Predictive Simulations of Musculoskeletal Function and Jumping Performance in a Generalized Bird. ACTA ACUST UNITED AC 2021; 3:obab006. [PMID: 34377939 PMCID: PMC8341896 DOI: 10.1093/iob/obab006] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Jumping is a common, but demanding, behavior that many animals employ during everyday activity. In contrast to jump-specialists such as anurans and some primates, jumping biomechanics and the factors that influence performance remains little studied for generalized species that lack marked adaptations for jumping. Computational biomechanical modeling approaches offer a way of addressing this in a rigorous, mechanistic fashion. Here, optimal control theory and musculoskeletal modeling are integrated to generate predictive simulations of maximal height jumping in a small ground-dwelling bird, a tinamou. A three-dimensional musculoskeletal model with 36 actuators per leg is used, and direct collocation is employed to formulate a rapidly solvable optimal control problem involving both liftoff and landing phases. The resulting simulation raises the whole-body center of mass to over double its standing height, and key aspects of the simulated behavior qualitatively replicate empirical observations for other jumping birds. However, quantitative performance is lower, with reduced ground forces, jump heights, and muscle–tendon power. A pronounced countermovement maneuver is used during launch. The use of a countermovement is demonstrated to be critical to the achievement of greater jump heights, and this phenomenon may only need to exploit physical principles alone to be successful; amplification of muscle performance may not necessarily be a proximate reason for the use of this maneuver. Increasing muscle strength or contractile velocity above nominal values greatly improves jump performance, and interestingly has the greatest effect on more distal limb extensor muscles (i.e., those of the ankle), suggesting that the distal limb may be a critical link for jumping behavior. These results warrant a re-evaluation of previous inferences of jumping ability in some extinct species with foreshortened distal limb segments, such as dromaeosaurid dinosaurs. Simulations prédictives de la fonction musculo-squelettique et des performances de saut chez un oiseau généralisé Sauter est un comportement commun, mais exigeant, que de nombreux animaux utilisent au cours de leurs activités quotidiennes. Contrairement aux spécialistes du saut tels que les anoures et certains primates, la biomécanique du saut et les facteurs qui influencent la performance restent peu étudiés pour les espèces généralisées qui n’ont pas d’adaptations marquées pour le saut. Les approches de modélisation biomécanique computationnelle offrent un moyen d’aborder cette question de manière rigoureuse et mécaniste. Ici, la théorie du contrôle optimal et la modélisation musculo-squelettique sont intégrées pour générer des simulations prédictives du saut en hauteur maximal chez un petit oiseau terrestre, le tinamou. Un modèle musculo-squelettique tridimensionnel avec 36 actionneurs par patte est utilisé, et une méthode numérique nommée “direct collocation” est employée pour formuler un problème de contrôle optimal rapidement résoluble impliquant les phases de décollage et d’atterrissage. La simulation qui en résulte élève le centre de masse du corps entier à plus du double de sa hauteur debout, et les aspects clés du comportement simulé reproduisent qualitativement les observations empiriques d’autres oiseaux sauteurs. Cependant, les performances quantitatives sont moindres, avec une réduction des forces au sol, des hauteurs de saut et de la puissance musculo-tendineuse. Une manœuvre de contre-mouvement prononcée est utilisée pendant le lancement. Il a été démontré que l’utilisation d’un contre-mouvement est essentielle à l’obtention de hauteurs de saut plus importantes, et il se peut que ce phénomène doive exploiter uniquement des principes physiques pour réussir; l’amplification de la performance musculaire n’est pas nécessairement une raison immédiate de l’utilisation de cette manœuvre. L’augmentation de la force musculaire ou de la vitesse de contraction au-dessus des valeurs nominales améliore grandement la performance de saut et, fait intéressant, a le plus grand effet sur les muscles extenseurs des membres plus distaux (c'est-à-dire ceux de la cheville), ce qui suggère que le membre distal peut être un lien critique pour le comportement de saut. Ces résultats justifient une réévaluation des déductions précédentes de la capacité de sauter chez certaines espèces éteintes avec des segments de membres distaux raccourcis, comme les dinosaures droméosauridés. Voorspellende simulaties van musculoskeletale functie en springprestaties bij een gegeneraliseerde vogel Springen is een veel voorkomend, maar veeleisend, gedrag dat veel dieren toepassen tijdens hun dagelijkse bezigheden. In tegenstelling tot de springspecialisten zoals de anura en sommige primaten, is de biomechanica van het springen en de factoren die de prestaties beïnvloeden nog weinig bestudeerd voor algemene soorten die geen uitgesproken adaptaties voor het springen hebben. Computationele biomechanische modelbenaderingen bieden een manier om dit op een rigoureuze, mechanistische manier aan te pakken. Hier worden optimale controle theorie en musculoskeletale modellering geïntegreerd om voorspellende simulaties te genereren van maximale hoogtesprong bij een kleine grondbewonende vogel, een tinamou. Een driedimensionaal musculoskeletaal model met 36 actuatoren per poot wordt gebruikt, en directe collocatie wordt toegepast om een snel oplosbaar optimaal controleprobleem te formuleren dat zowel de opstijg-als de landingsfase omvat. De resulterende simulatie verhoogt het lichaamszwaartepunt tot meer dan het dubbele van de stahoogte, en belangrijke aspecten van het gesimuleerde gedrag komen kwalitatief overeen met empirische waarnemingen voor andere springende vogels. De kwantitatieve prestaties zijn echter minder, met verminderde grondkrachten, spronghoogtes en spierpeeskracht. Tijdens de lancering wordt een uitgesproken tegenbewegingsmanoeuvre gebruikt. Aangetoond is dat het gebruik van een tegenbeweging van cruciaal belang is voor het bereiken van grotere spronghoogten, en dit fenomeen hoeft alleen op fysische principes te berusten om succesvol te zijn; versterking van de spierprestaties hoeft niet noodzakelijk een proximate reden te zijn voor het gebruik van deze manoeuvre. Het verhogen van de spierkracht of van de contractiesnelheid boven de nominale waarden verbetert de sprongprestatie aanzienlijk, en heeft interessant genoeg het grootste effect op de meer distale extensoren van de ledematen (d.w.z. die van de enkel), wat suggereert dat de distale ledematen een kritieke schakel kunnen zijn voor het springgedrag. Deze resultaten rechtvaardigen een herevaluatie van eerdere conclusies over springvermogen bij sommige uitgestorven soorten met voorgekorte distale ledematen, zoals dromaeosauride dinosauriërs. Prädiktive Simulationen der muskuloskelettalen Funktion und Sprungleistung bei einem generalisierten Vogel Springen ist ein übliches jedoch anstrengendes Verhalten, das viele Tiere bei ihren täglichen Aktivitäten einsetzen. Im Gegensatz zu Springspezialisten, wie Fröschen und einigen Primaten, sind bei allgemeinen Arten, welche keine ausgeprägten Anpassung für Sprungverhalten aufweisen, die Biomechanik beim Springen und die Faktoren, welche die Leistungsfähigkeit beeinflussen, noch wenig untersucht. Computergestützte biomechanische Modellierungsverfahren bieten hier eine Möglichkeit, dies in einer gründlichen, mechanistischen Weise anzugehen. In dieser Arbeit werden die optimale Steuerungstheorie und Muskel-Skelett-Modellierung zusammen eingesetzt, um die maximale Sprunghöhe eines kleinen bodenlebenden Vogels, eines Perlsteisshuhns, zu simulieren und zu prognostizieren. Es wird ein dreidimensionales Muskel-Skelett-Modell mit 36 Aktuatoren pro Bein verwendet, und durch direkte Kollokation wird ein schnell lösbares optimales Steuerungsproblem formuliert, das sowohl die Abstoss- als auch die Landephase umfasst. Die daraus folgende Simulation bringt den Ganzkörperschwerpunkt auf mehr als das Doppelte seiner Standhöhe und entscheidende Aspekte des simulierten Verhaltens entsprechen qualitativ empirischen Beobachtungen für andere springende Vögel. Allerdings ist die quantitative Leistungsfähigkeit geringer, mit reduzierten Bodenkräften, Sprunghöhen und Muskel-Sehnen-Kräften. Beim Abstossen wird ein ausgeprägtes Gegenbewegungsmanöver durchgeführt. Die Durchführung einer Gegenbewegung ist nachweislich entscheidend für das Erreichen grösserer Sprunghöhen, wobei dieses Phänomen möglicherweise nur physikalische Prinzipien auszuschöpfen braucht, um erfolgreich zu sein. Die Verstärkung der Muskelleistung ist daher möglicherweise nicht zwingend ein unmittelbarer Grund für die Verwendung dieses Manövers. Eine Erhöhung der Muskelkraft oder der Kontraktionsgeschwindigkeit über die Nominalwerte hinaus führt zu einer erheblichen Zunahme der Sprungleistung und hat interessanterweise den grössten Effekt bei den weiter distal gelegenen Streckmuskeln der Beine (d.h. bei denjenigen des Sprunggelenks), was darauf hindeutet, dass die distale Gliedmasse ein entscheidendes Element für das Sprungverhalten sein könnte. Diese Ergebnisse geben Anlass zur Überprüfung früherer Schlussfolgerungen hinsichtlich der Sprungfähigkeit einiger ausgestorbener Arten mit verkürzten distalen Gliedmassen, wie beispielsweise bei dromaeosauriden Dinosauriern.
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Affiliation(s)
- P J Bishop
- Structure and Motion Laboratory, Department of Comparative Biomedical Sciences, Royal Veterinary College, Hatfield, UK.,Geosciences Program, Queensland Museum, Brisbane, Australia.,Museum of Comparative Zoology, Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
| | - A Falisse
- Department of Movement Sciences, KU Leuven, Leuven, Belgium.,Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| | - F De Groote
- Department of Movement Sciences, KU Leuven, Leuven, Belgium
| | - J R Hutchinson
- Structure and Motion Laboratory, Department of Comparative Biomedical Sciences, Royal Veterinary College, Hatfield, UK
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Tomalka A, Weidner S, Hahn D, Seiberl W, Siebert T. Power Amplification Increases With Contraction Velocity During Stretch-Shortening Cycles of Skinned Muscle Fibers. Front Physiol 2021; 12:644981. [PMID: 33868012 PMCID: PMC8044407 DOI: 10.3389/fphys.2021.644981] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Accepted: 03/08/2021] [Indexed: 01/25/2023] Open
Abstract
Muscle force, work, and power output during concentric contractions (active muscle shortening) are increased immediately following an eccentric contraction (active muscle lengthening). This increase in performance is known as the stretch-shortening cycle (SSC)-effect. Recent findings demonstrate that the SSC-effect is present in the sarcomere itself. More recently, it has been suggested that cross-bridge (XB) kinetics and non-cross-bridge (non-XB) structures (e.g., titin and nebulin) contribute to the SSC-effect. As XBs and non-XB structures are characterized by a velocity dependence, we investigated the impact of stretch-shortening velocity on the SSC-effect. Accordingly, we performed in vitro isovelocity ramp experiments with varying ramp velocities (30, 60, and 85% of maximum contraction velocity for both stretch and shortening) and constant stretch-shortening magnitudes (17% of the optimum sarcomere length) using single skinned fibers of rat soleus muscles. The different contributions of XB and non-XB structures to force production were identified using the XB-inhibitor Blebbistatin. We show that (i) the SSC-effect is velocity-dependent-since the power output increases with increasing SSC-velocity. (ii) The energy recovery (ratio of elastic energy storage and release in the SSC) is higher in the Blebbistatin condition compared with the control condition. The stored and released energy in the Blebbistatin condition can be explained by the viscoelastic properties of the non-XB structure titin. Consequently, our experimental findings suggest that the energy stored in titin during the eccentric phase contributes to the SSC-effect in a velocity-dependent manner.
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Affiliation(s)
- André Tomalka
- Department of Motion and Exercise Science, University of Stuttgart, Stuttgart, Germany
| | - Sven Weidner
- Department of Motion and Exercise Science, University of Stuttgart, Stuttgart, Germany
| | - Daniel Hahn
- Human Movement Science, Faculty of Sports Science, Ruhr University Bochum, Bochum, Germany
- School of Human Movement and Nutrition Sciences, University of Queensland, Brisbane, QLD, Australia
| | - Wolfgang Seiberl
- Human Movement Science, Bundeswehr University Munich, Neubiberg, Germany
| | - Tobias Siebert
- Department of Motion and Exercise Science, University of Stuttgart, Stuttgart, Germany
- Stuttgart Center for Simulation Science, University of Stuttgart, Stuttgart, Germany
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Fountain WA, Valenti ZJ, Lynch CE, Guarnera SR, Meister BM, Carlini NA, Lynch KE, Kuszmaul DJ, Chaves AB, Mazzetti SA. Order of concentric and eccentric muscle actions affects metabolic responses. J Sports Med Phys Fitness 2021; 61:1587-1595. [PMID: 33480518 DOI: 10.23736/s0022-4707.21.12010-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
BACKGROUND Resistance exercise provides an effective stimulus for improving the metabolic plasticity of skeletal muscle, and the type of acute muscle contraction plays an important role in determining specific responses and adaptations. The purpose of the current investigation was to examine the effect of contraction order on metabolic responses by comparing monophasic concentric and eccentric squats versus a protocol incorporating alternated concentric and eccentric repetitions. METHODS Twelve recreationally active men (21.1±1.1yr) performed three nearly identical squat protocols on separate days. Protocols varied only with contraction-type, including 4 sets × 10 reps concentric-only (CON), eccentric-only (ECC), and BOTH which alternated 5 concentric followed by 5 eccentric reps (CON-ECC; sets 1 and 3) and vice versa (ECC-CON; sets 2 and 4). The experimental trials were performed once weekly in a randomized, counter-balanced order, and expired gases were collected using a two-way non-rebreathing mask and oxygen consumption quantified with indirect calorimetry. Subjects raised (CON) and lowered (ECC) the load in 2s, and all sets (2 min) and repetitions (8 s) were separated by standardized rest intervals. RESULTS From the BOTH protocol, the increase in metabolic rate was significantly greater (P≤0.05) during squats performed with CON-ECC order (0.60±0.11 L·min-1) compared to ECC-CON (0.44±0.07 L·min-1), but excess postexercise oxygen consumption (EPOC) was opposite, with significantly greater metabolic rate during the 2-minute rest intervals after ECC-CON squats (0.46±0.09 L·min-1) compared to CON-ECC (0.25±0.05 L·min-1). Metabolic rates during and after squats were significantly greater (P≤0.05) with CON (0.63±0.09; 0.49±0.10 L·min-1) compared to ECC (0.34±0.04; 0.20±0.04 L·min-1), respectively. CONCLUSIONS These data present an interesting paradigm regarding the contraction-dependent metabolic responses to monophasic resistance exercise and suggest a greater EPOC following concentric versus eccentric muscle actions.
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Affiliation(s)
- William A Fountain
- School of Health Sciences, Laboratory for Human Performance, Salisbury University, Salisbury, MD, USA
| | - Zackary J Valenti
- School of Health Sciences, Laboratory for Human Performance, Salisbury University, Salisbury, MD, USA
| | - Colleen E Lynch
- School of Health Sciences, Laboratory for Human Performance, Salisbury University, Salisbury, MD, USA
| | - Samantha R Guarnera
- School of Health Sciences, Laboratory for Human Performance, Salisbury University, Salisbury, MD, USA
| | - Benjamin M Meister
- School of Health Sciences, Laboratory for Human Performance, Salisbury University, Salisbury, MD, USA
| | - Nicholas A Carlini
- School of Health Sciences, Laboratory for Human Performance, Salisbury University, Salisbury, MD, USA
| | - Kerry E Lynch
- School of Health Sciences, Laboratory for Human Performance, Salisbury University, Salisbury, MD, USA
| | - Dillon J Kuszmaul
- School of Health Sciences, Laboratory for Human Performance, Salisbury University, Salisbury, MD, USA
| | - Alec B Chaves
- School of Health Sciences, Laboratory for Human Performance, Salisbury University, Salisbury, MD, USA
| | - Scott A Mazzetti
- School of Health Sciences, Laboratory for Human Performance, Salisbury University, Salisbury, MD, USA -
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Can Exercise-Induced Muscle Damage Be a Good Model for the Investigation of the Anti-Inflammatory Properties of Diet in Humans? Biomedicines 2021; 9:biomedicines9010036. [PMID: 33466327 PMCID: PMC7824757 DOI: 10.3390/biomedicines9010036] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 12/23/2020] [Accepted: 12/29/2020] [Indexed: 12/25/2022] Open
Abstract
Subclinical, low-grade, inflammation is one of the main pathophysiological mechanisms underlying the majority of chronic and non-communicable diseases. Several methodological approaches have been applied for the assessment of the anti-inflammatory properties of nutrition, however, their impact in human body remains uncertain, because of the fact that the majority of the studies reporting anti-inflammatory effect of dietary patterns, have been performed under laboratory settings and/or in animal models. Thus, the extrapolation of these results to humans is risky. It is therefore obvious that the development of an inflammatory model in humans, by which we could induce inflammatory responses to humans in a regulated, specific, and non-harmful way, could greatly facilitate the estimation of the anti-inflammatory properties of diet in a more physiological way and mechanistically relevant way. We believe that exercise-induced muscle damage (EIMD) could serve as such a model, either in studies investigating the homeostatic responses of individuals under inflammatory stimuli or for the estimation of the anti-inflammatory or pro-inflammatory potential of dietary patterns, foods, supplements, nutrients, or phytochemicals. Thus, in this review we discuss the possibility of exercise-induced muscle damage being an inflammation model suitable for the assessment of the anti-inflammatory properties of diet in humans.
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Gasser B, Fitze D, Franchi M, Frei A, Niederseer D, Schmied CM, Catuogno S, Frey W, Flück M. The Cardiovascular Response to Interval Exercise Is Modified by the Contraction Type and Training in Proportion to Metabolic Stress of Recruited Muscle Groups. SENSORS 2020; 21:s21010173. [PMID: 33383837 PMCID: PMC7795051 DOI: 10.3390/s21010173] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 12/23/2020] [Accepted: 12/23/2020] [Indexed: 01/20/2023]
Abstract
Background: Conventional forms of endurance training based on shortening contractions improve aerobic capacity but elicit a detriment of muscle strength. We hypothesized that eccentric interval training, loading muscle during the lengthening phase of contraction, overcome this interference and potentially adverse cardiovascular reactions, enhancing both muscle metabolism and strength, in association with the stress experienced during exercise. Methods: Twelve healthy participants completed an eight-week program of work-matched progressive interval-type pedaling exercise on a soft robot under predominately concentric or eccentric load. Results: Eccentric interval training specifically enhanced the peak power of positive anaerobic contractions (+28%), mitigated the strain on muscle’s aerobic metabolism, and lowered hemodynamic stress during interval exercise, concomitant with a lowered contribution of positive work to the target output. Concentric training alone lowered blood glucose concentration during interval exercise and mitigated heart rate and blood lactate concentration during ramp exercise. Training-induced adjustments for lactate and positive peak power were independently correlated (p < 0.05, |r| > 0.7) with indices of metabolic and mechanical muscle stress during exercise. Discussion: Task-specific improvements in strength and muscle’s metabolic capacity were induced with eccentric interval exercise lowering cardiovascular risk factors, except for blood glucose concentration, possibly through altered neuromuscular coordination.
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Affiliation(s)
- Benedikt Gasser
- Departement für Sport, Bewegung und Gesundheit—Abteilung Rehabilitative und Regenerative Sportmedizin—Universität Basel—Birsstrasse, 320B CH, 4052 Basel, Switzerland;
| | - Daniel Fitze
- Laboratory for Muscle Plasticity, Departement of Orthopaedics Balgrist Campus, University of Zurich Lengghalde, 8008 Zürich, Switzerland; (D.F.); (A.F.); (S.C.); (W.F.)
- Balgrist University Hospital Forchstrasse 319, 8008 Zürich, Switzerland
| | - Martino Franchi
- Department of Biomedical Sciences, University of Padova, 35131 Padua, Italy;
| | - Annika Frei
- Laboratory for Muscle Plasticity, Departement of Orthopaedics Balgrist Campus, University of Zurich Lengghalde, 8008 Zürich, Switzerland; (D.F.); (A.F.); (S.C.); (W.F.)
- Balgrist University Hospital Forchstrasse 319, 8008 Zürich, Switzerland
| | - David Niederseer
- Sports Cardiology Section, Department of Cardiology, University Heart Center Zurich, University Hospital Zurich, University of Zurich, 8091 Zurich, Switzerland; (D.N.); (C.M.S.)
| | - Christian M. Schmied
- Sports Cardiology Section, Department of Cardiology, University Heart Center Zurich, University Hospital Zurich, University of Zurich, 8091 Zurich, Switzerland; (D.N.); (C.M.S.)
| | - Silvio Catuogno
- Laboratory for Muscle Plasticity, Departement of Orthopaedics Balgrist Campus, University of Zurich Lengghalde, 8008 Zürich, Switzerland; (D.F.); (A.F.); (S.C.); (W.F.)
- Balgrist University Hospital Forchstrasse 319, 8008 Zürich, Switzerland
| | - Walter Frey
- Laboratory for Muscle Plasticity, Departement of Orthopaedics Balgrist Campus, University of Zurich Lengghalde, 8008 Zürich, Switzerland; (D.F.); (A.F.); (S.C.); (W.F.)
- Balgrist University Hospital Forchstrasse 319, 8008 Zürich, Switzerland
| | - Martin Flück
- Laboratory for Muscle Plasticity, Departement of Orthopaedics Balgrist Campus, University of Zurich Lengghalde, 8008 Zürich, Switzerland; (D.F.); (A.F.); (S.C.); (W.F.)
- Balgrist University Hospital Forchstrasse 319, 8008 Zürich, Switzerland
- Correspondence:
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Cankaya AO, Pamuk U, Yucesoy CA. The effects of an activation-dependent increase in titin stiffness on whole muscle properties using finite element modeling. J Biomech 2020; 116:110197. [PMID: 33412436 DOI: 10.1016/j.jbiomech.2020.110197] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2020] [Revised: 11/28/2020] [Accepted: 12/11/2020] [Indexed: 12/31/2022]
Abstract
Active state titin's effects have been studied predominantly in sarcomere or muscle fiber segment level and an understanding of its functional effects in the context of a whole muscle, and the mechanism of those is lacking. By representing experimentally observed calcium induced stiffening and actin-titin interaction induced reduced free spring length effects of active state titin in our linked fiber-matrix mesh finite element model, our aim was to study the mechanism of effects and particularly to determine the functionally more effective active state titin model. Isolated EDL muscle of the rat was modeled and three cases were studied: passive state titin (no change in titin constitutive equation in the active state), active state titin-I (constitutive equation involves a higher stiffness in the active state) and active state titin-II (constitutive equation also involves a strain shift coefficient accounting for titin's reduced free spring length). Isometric muscle lengthening was imposed (initial to long length, lm = 28.7 mm to 32.7 mm). Compared to passive state titin, (i) active state titin-I and II elevates muscle total (lm = 32.7 mm: 14% and 29%, respectively) and active (lm = 32.7 mm: 37.5% and 77.4%, respectively) forces, (ii) active state titin-II also shifts muscle's optimum length to a longer length (lm = 29.6 mm), (iii) active state titin-I and II limits sarcomere shortening (lm = 32.7 mm: up to 10% and 20%, respectively). Such shorter sarcomere effect characterizes active state titin's mechanism of effects. These effects become more pronounced and functionally more effective if not only calcium induced stiffening but also a reduced free spring length of titin is accounted for.
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Affiliation(s)
- Alican O Cankaya
- Institute of Biomedical Engineering, Boğaziçi University, Istanbul, Turkey
| | - Uluç Pamuk
- Institute of Biomedical Engineering, Boğaziçi University, Istanbul, Turkey
| | - Can A Yucesoy
- Institute of Biomedical Engineering, Boğaziçi University, Istanbul, Turkey.
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25
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Hill MW, Hosseini EA, McLellan A, Price MJ, Lord SR, Kay AD. Delayed Impairment of Postural, Physical, and Muscular Functions Following Downhill Compared to Level Walking in Older People. Front Physiol 2020; 11:544559. [PMID: 33192547 PMCID: PMC7609421 DOI: 10.3389/fphys.2020.544559] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2020] [Accepted: 09/18/2020] [Indexed: 11/15/2022] Open
Abstract
Transient symptoms of muscle damage emanating from unaccustomed eccentric exercise can adversely affect muscle function and potentially increase the risk of falling for several days. Therefore, the aims of the present study were to investigate the shorter- and longer-lasting temporal characteristics of muscle fatigue and damage induced by level (i.e., concentrically biased contractions) or downhill (i.e., eccentrically biased contractions) walking on postural, physical, and muscular functions in older people. Nineteen participants were matched in pairs for sex, age and self-selected walking speed and allocated to a level (n = 10, age = 72.3 ± 2.9 years) or downhill (n = 9, age = 72.1 ± 2.2 years) walking group. Postural sway, muscle torque and power, physical function (5× and 60 s sit-to-stand; STS), and mobility (Timed-Up-and-Go; TUG) were evaluated at baseline (pre-exercise), 1 min, 15 min, 30 min, 24 h, and 48 h after 30 min of level (0% gradient) or downhill (−10% gradient) walking on a treadmill. Following downhill walking, postural sway (+66 to 256%), TUG (+29%), 60 s STS (+29%), five times STS (−25%) and concentric power (−33%) did not change at 1–30 min post exercise, but were significantly different (p < 0.05) at 24 and48 h post-exercise when compared to baseline (p < 0.05). Muscle torque decreased immediately after downhill walking and remained impaired at 48 h post-exercise (−27 to −38%). Immediately following level walking there was an increase in postural sway (+52 to +98%), slower TUG performance (+29%), fewer STS cycles in 60 s (−23%), slower time to reach five STS cycles (+20%) and impaired muscle torque (−23%) and power (−19%) which returned to baseline 30-min after exercise cessation (p > 0.05). These findings have established for the first time distinct impairment profiles between concentric and eccentric exercise. Muscle damage emanating from eccentrically biased exercise can lead to muscle weakness, postural instability and impaired physical function persisting for several days, possibly endangering older adult’s safety during activities of daily living by increasing the risk of falls.
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Affiliation(s)
- Mathew William Hill
- Centre for Sport, Exercise and Life Sciences, Coventry University, Coventry, United Kingdom
| | - Edyah-Ariella Hosseini
- Centre for Sport, Exercise and Life Sciences, Coventry University, Coventry, United Kingdom
| | - Abbie McLellan
- Centre for Sport, Exercise and Life Sciences, Coventry University, Coventry, United Kingdom
| | - Michael James Price
- Centre for Sport, Exercise and Life Sciences, Coventry University, Coventry, United Kingdom
| | - Stephen Ronald Lord
- Falls, Balance and Injury Research Centre, Neuroscience Research Australia, University of New South Wales, Sydney, NSW, Australia
| | - Anthony David Kay
- Centre for Physical Activity and Life Sciences, University of Northampton, Northampton, United Kingdom
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26
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Fukutani A, Herzog W. Differences in stretch-shortening cycle and residual force enhancement between muscles. J Biomech 2020; 112:110040. [PMID: 32980750 DOI: 10.1016/j.jbiomech.2020.110040] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2020] [Revised: 08/30/2020] [Accepted: 08/31/2020] [Indexed: 01/18/2023]
Abstract
It has been suggested that cross bridge kinetics and residual force enhancement (RFE) affect force in the stretch-shortening cycle (SSC). Because cross bridge kinetics and titin isoforms, which are thought to be related to RFE, differ between muscles, the SSC effect may be also muscle-dependent. Thus, we compared the SSC effect between psoas and soleus muscles, which have a distinct fiber type distribution and different titin isoforms. Four tests (SSC, SSC control, RFE, RFE control) were conducted using isolated, skinned fibers of psoas and soleus. In the SSC tests, fibers were activated at an average sarcomere length of 2.4 μm, stretched to 3.0 μm, and shortened to 2.4 μm. In the SSC control tests, fibers were activated at an average sarcomere length of 3.0 μm and then shortened to 2.4 μm. The relative increase in mechanical work obtained during shortening between tests was defined as the SSC effect. In the RFE tests, fibers were activated at an average sarcomere length of 2.4 μm and then stretched to 3.0 μm, while the RFE control tests consisted of an isometric contraction at 3.0 μm. The difference in steady-state isometric force between tests was defined as RFE. The SSC effect was greater in soleus than in psoas, while the RFE was the same for both muscles. Since the SSC effect was greater in soleus, while the RFE was the same, the observed greater SSC effect is probably not directly caused by RFE, but may be related to differences in cross bridge kinetics.
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Affiliation(s)
- Atsuki Fukutani
- Faculty of Sport and Health Science, Ritsumeikan University, 1-1-1 Noji-higashi, Kusatsu, Shiga 525-8577, Japan.
| | - Walter Herzog
- Faculty of Kinesiology, The University of Calgary, 2500 University Drive, NW, Calgary, AB T2N 1N4, Canada
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27
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Green B, Lin M, McClelland JA, Semciw AI, Schache AG, Rotstein AH, Cook J, Pizzari T. Return to Play and Recurrence After Calf Muscle Strain Injuries in Elite Australian Football Players. Am J Sports Med 2020; 48:3306-3315. [PMID: 33030961 DOI: 10.1177/0363546520959327] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND Calf muscle strain injuries (CMSI) are prevalent in sport, but information about factors associated with time to return to play (RTP) and recurrence is limited. PURPOSE To determine whether clinical and magnetic resonance imaging (MRI) data are associated with RTP and recurrence after CMSI. STUDY DESIGN Case-control study; Level of evidence, 3. METHODS Data of 149 CMSI reported to the Soft Tissue injury Registry of the Australian Football League were explored to evaluate the impact of clinical data and index injury MRI findings on RTP and recurrence. Clinical data included age, previous injury history, ethnicity, and the mechanism of injury. RESULTS Irrespective of the anatomical location, players with CMSI with severe aponeurotic disruption (AD) took longer to RTP than players with CMSI with no AD: 31.3 ± 12.6 days vs 19.4 ± 10.8 days (mean ± SD; P = .003). A running-related mechanism of injury was associated with a longer RTP period for CMSI overall (adjusted hazard ratio [AHR], 0.59; P = .02). The presence of AD was associated with a longer RTP period for soleus injuries (AHR, 0.6; P = .025). Early recurrence (ie, ≤2 months of the index injury) was associated with older age (AHR, 1.3; P = .001) and a history of ankle injury (AHR, 3.9; P = .032). Older age (AHR, 1.1; P = .013) and a history of CMSI (AHR, 6.7; P = .002) increased the risk of recurrence within 2 seasons. The index injury MRI findings were not associated with risk of recurrence. CONCLUSION A running-related mechanism of injury and the presence of AD on MRI were associated with a longer RTP period. Clinical rather than MRI data best indicate the risk of recurrent CMSI.
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Affiliation(s)
- Brady Green
- La Trobe Sport and Exercise Medicine Research Centre, La Trobe University, Melbourne, Australia
| | - Monica Lin
- Victoria House Medical Imaging, Melbourne, Australia
| | - Jodie A McClelland
- La Trobe Sport and Exercise Medicine Research Centre, La Trobe University, Melbourne, Australia
| | - Adam I Semciw
- La Trobe Sport and Exercise Medicine Research Centre, La Trobe University, Melbourne, Australia.,Northern Centre for Health Education and Research, Northern Health, Victoria, Australia
| | - Anthony G Schache
- La Trobe Sport and Exercise Medicine Research Centre, La Trobe University, Melbourne, Australia
| | | | - Jill Cook
- La Trobe Sport and Exercise Medicine Research Centre, La Trobe University, Melbourne, Australia
| | - Tania Pizzari
- La Trobe Sport and Exercise Medicine Research Centre, La Trobe University, Melbourne, Australia
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Chen J, Mashouri P, Fontyn S, Valvano M, Elliott-Mohamed S, Noonan AM, Brown SHM, Power GA. The influence of training-induced sarcomerogenesis on the history dependence of force. J Exp Biol 2020; 223:jeb218776. [PMID: 32561632 DOI: 10.1242/jeb.218776] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2019] [Accepted: 06/09/2020] [Indexed: 12/21/2022]
Abstract
The increase or decrease in isometric force following active muscle lengthening or shortening, relative to a reference isometric contraction at the same muscle length and level of activation, are referred to as residual force enhancement (rFE) and residual force depression (rFD), respectively. The purpose of these experiments was to investigate the trainability of rFE and rFD on the basis of serial sarcomere number (SSN) alterations to history-dependent force properties. Maximal rFE/rFD measures from the soleus and extensor digitorum longus (EDL) of rats were compared after 4 weeks of uphill or downhill running with a no-running control. SSN adapted to the training: soleus SSN was greater with downhill compared with uphill running, while EDL demonstrated a trend towards more SSN for downhill compared with no running. In contrast, rFE and rFD did not differ across training groups for either muscle. As such, it appears that training-induced SSN adaptations do not modify rFE or rFD at the whole-muscle level.
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Affiliation(s)
- Jackey Chen
- Department of Human Health and Nutritional Sciences, College of Biological Sciences, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Parastoo Mashouri
- Department of Human Health and Nutritional Sciences, College of Biological Sciences, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Stephanie Fontyn
- Department of Human Health and Nutritional Sciences, College of Biological Sciences, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Mikella Valvano
- Department of Human Health and Nutritional Sciences, College of Biological Sciences, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Shakeap Elliott-Mohamed
- Department of Human Health and Nutritional Sciences, College of Biological Sciences, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Alex M Noonan
- Department of Human Health and Nutritional Sciences, College of Biological Sciences, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Stephen H M Brown
- Department of Human Health and Nutritional Sciences, College of Biological Sciences, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Geoffrey A Power
- Department of Human Health and Nutritional Sciences, College of Biological Sciences, University of Guelph, Guelph, ON N1G 2W1, Canada
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Increased fascicle length but not patellar tendon stiffness after accentuated eccentric-load strength training in already-trained men. Eur J Appl Physiol 2020; 120:2371-2382. [PMID: 32772246 PMCID: PMC7560914 DOI: 10.1007/s00421-020-04462-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 08/04/2020] [Indexed: 01/28/2023]
Abstract
Purpose This study examined whether additional external load during the eccentric phase of lower limb strength training exercises led to greater adaptations in knee extensor strength, muscle architecture, and patellar tendon properties than traditional concentric–eccentric training in already-trained men. Methods Twenty-eight men accustomed to strength training were randomized to undertake 10 weeks of supervised traditional (TRAD) or accentuated eccentric loading (AEL) or continue their habitual unsupervised (CON) strength training. TRAD and AEL trained 2∙week−1 with a six-repetition maximum (RM) session and a ten-RM session. TRAD used the same external load in both concentric and eccentric phases, while AEL used 40% greater load during the eccentric than concentric phase. Tests were performed at pre- and post-training, including: maximum unilateral isokinetic (30°·s−1) concentric, eccentric and isometric torques by isokinetic dynamometry, unilateral isometric ramp contractions with muscle–tendon ultrasound imaging to measure tendon stiffness and hysteresis, and resting vastus lateralis and medialis fascicle angle and length measured by extended-field-of-view ultrasound. Results After training, both TRAD and AEL significantly increased maximum concentric and isometric torque (p < 0.05), but only AEL increased eccentric torque (AEL: + 10 ± 9%, TRAD: + 4 ± 9%) and vastus lateralis (AEL: + 14 ± 14%, TRAD: + 1 ± 10%) and medialis (AEL: + 19 ± 8%, TRAD: + 5 ± 11%) fascicle length. Conclusion Both TRAD and AEL increased maximum knee extensor strength but only AEL increased VL and VM fascicle length. Neither training program promoted changes in fascicle angle or changes in patellar tendon properties in our already-trained men.
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30
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Maestroni L, Read P, Bishop C, Turner A. Strength and Power Training in Rehabilitation: Underpinning Principles and Practical Strategies to Return Athletes to High Performance. Sports Med 2020; 50:239-252. [PMID: 31559567 DOI: 10.1007/s40279-019-01195-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Injuries have a detrimental impact on team and individual athletic performance. Deficits in maximal strength, rate of force development (RFD), and reactive strength are commonly reported following several musculoskeletal injuries. This article first examines the available literature to identify common deficits in fundamental physical qualities following injury, specifically strength, rate of force development and reactive strength. Secondly, evidence-based strategies to target a resolution of these residual deficits will be discussed to reduce the risk of future injury. Examples to enhance practical application and training programmes have also been provided to show how these can be addressed.
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Affiliation(s)
- Luca Maestroni
- Smuoviti, Viale Giulio Cesare, 29, 24121, Bergamo, BG, Italy.
- StudioErre, Via della Badia, 18, 25127, Brescia, BS, Italy.
| | - Paul Read
- Athlete Health and Performance Research Center, Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Qatar
| | - Chris Bishop
- London Sport Institute, School of Science and Technology, Middlesex University, Greenlands Lane, London, UK
| | - Anthony Turner
- London Sport Institute, School of Science and Technology, Middlesex University, Greenlands Lane, London, UK
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N2A Titin: Signaling Hub and Mechanical Switch in Skeletal Muscle. Int J Mol Sci 2020; 21:ijms21113974. [PMID: 32492876 PMCID: PMC7312179 DOI: 10.3390/ijms21113974] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 05/30/2020] [Accepted: 06/01/2020] [Indexed: 02/06/2023] Open
Abstract
Since its belated discovery, our understanding of the giant protein titin has grown exponentially from its humble beginning as a sarcomeric scaffold to recent recognition of its critical mechanical and signaling functions in active muscle. One uniquely useful model to unravel titin’s functions, muscular dystrophy with myositis (mdm), arose spontaneously in mice as a transposon-like LINE repeat insertion that results in a small deletion in the N2A region of titin. This small deletion profoundly affects hypertrophic signaling and muscle mechanics, thereby providing insights into the function of this specific region and the consequences of its dysfunction. The impact of this mutation is profound, affecting diverse aspects of the phenotype including muscle mechanics, developmental hypertrophy, and thermoregulation. In this review, we explore accumulating evidence that points to the N2A region of titin as a dynamic “switch” that is critical for both mechanical and signaling functions in skeletal muscle. Calcium-dependent binding of N2A titin to actin filaments triggers a cascade of changes in titin that affect mechanical properties such as elastic energy storage and return, as well as hypertrophic signaling. The mdm phenotype also points to the existence of as yet unidentified signaling pathways for muscle hypertrophy and thermoregulation, likely involving titin’s PEVK region as well as the N2A signalosome.
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32
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Richards CT, Eberhard EA. In vitro virtual reality: an anatomically explicit musculoskeletal simulation powered by in vitro muscle using closed-loop tissue-software interaction. J Exp Biol 2020; 223:jeb210054. [PMID: 32253284 DOI: 10.1242/jeb.210054] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Accepted: 03/20/2020] [Indexed: 11/20/2022]
Abstract
Muscle force-length dynamics are governed by intrinsic contractile properties, motor stimulation and mechanical load. Although intrinsic properties are well characterised, physiologists lack in vitro instrumentation to account for combined effects of limb inertia, musculoskeletal architecture and contractile dynamics. We introduce in vitro virtual reality (in vitro-VR) which enables in vitro muscle tissue to drive a musculoskeletal jumping simulation. In hardware, muscle force from a frog plantaris was transmitted to a software model where joint torques, inertia and ground reaction forces were computed to advance the simulation at 1 kHz. To close the loop, simulated muscle strain was returned to update in vitro length. We manipulated (1) stimulation timing and (2) the virtual muscle's anatomical origin. This influenced interactions among muscular, inertial, gravitational and contact forces dictating limb kinematics and jump performance. We propose that in vitro-VR can be used to illustrate how neuromuscular control and musculoskeletal anatomy influence muscle dynamics and biomechanical performance.
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Abstract
Muscle has conventionally been viewed as a motor that converts chemical to kinetic energy in series with a passive spring, but new insights emerge when muscle is viewed as a composite material whose elastic elements are tuned by activation. New evidence demonstrates that calcium-dependent binding of N2A titin to actin increases titin stiffness in active skeletal muscles, which explains many long-standing enigmas of muscle physiology.
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Affiliation(s)
- Kiisa Nishikawa
- Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona
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Tahir U, Monroy JA, Rice NA, Nishikawa KC. Effects of a titin mutation on force enhancement and force depression in mouse soleus muscles. ACTA ACUST UNITED AC 2020; 223:jeb.197038. [PMID: 31862847 DOI: 10.1242/jeb.197038] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2019] [Accepted: 12/19/2019] [Indexed: 01/20/2023]
Abstract
The active isometric force produced by muscles varies with muscle length in accordance with the force-length relationship. Compared with isometric contractions at the same final length, force increases after active lengthening (force enhancement) and decreases after active shortening (force depression). In addition to cross-bridges, titin has been suggested to contribute to force enhancement and depression. Although titin is too compliant in passive muscles to contribute to active tension at short sarcomere lengths on the ascending limb and plateau of the force-length relationship, recent evidence suggests that activation increases titin stiffness. To test the hypothesis that titin plays a role in force enhancement and depression, we investigated isovelocity stretching and shortening in active and passive wild-type and mdm (muscular dystrophy with myositis) soleus muscles. Skeletal muscles from mdm mice have a small deletion in the N2A region of titin and show no increase in titin stiffness during active stretch. We found that: (1) force enhancement and depression were reduced in mdm soleus compared with wild-type muscles relative to passive force after stretch or shortening to the same final length; (2) force enhancement and force depression increased with amplitude of stretch across all activation levels in wild-type muscles; and (3) maximum shortening velocity of wild-type and mdm muscles estimated from isovelocity experiments was similar, although active stress was reduced in mdm compared with wild-type muscles. The results of this study suggest a role for titin in force enhancement and depression, which contribute importantly to muscle force during natural movements.
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Affiliation(s)
- Uzma Tahir
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011-5640, USA
| | - Jenna A Monroy
- W. M. Keck Science Department, The Claremont Colleges, Claremont, CA 91711-5916, USA
| | - Nicole A Rice
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011-5640, USA
| | - Kiisa C Nishikawa
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011-5640, USA
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35
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Libby T, Chukwueke C, Sponberg S. History-dependent perturbation response in limb muscle. ACTA ACUST UNITED AC 2020; 223:jeb.199018. [PMID: 31822554 DOI: 10.1242/jeb.199018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2019] [Accepted: 12/02/2019] [Indexed: 11/20/2022]
Abstract
Muscle mediates movement but movement is typically unsteady and perturbed. Muscle is known to behave non-linearly and with history-dependent properties during steady locomotion, but the importance of history dependence in mediating muscle function during perturbations remains less clear. To explore the capacity of muscles to mitigate perturbations during locomotion, we constructed a series of perturbations that varied only in kinematic history, keeping instantaneous position, velocity and time from stimulation constant. We found that the response of muscle to a perturbation is profoundly history dependent, varying 4-fold as baseline frequency changes, and dissipating energy equivalent to ∼6 times the kinetic energy of all the limbs in 5 ms (nearly 2400 W kg-1). Muscle energy dissipation during a perturbation is predicted primarily by the force at the onset of the perturbation. This relationship holds across different frequencies and timings of stimulation. This history dependence behaves like a viscoelastic memory producing perturbation responses that vary with the frequency of the underlying movement.
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Affiliation(s)
| | - Chidinma Chukwueke
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Simon Sponberg
- School of Physics and School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
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36
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Fukutani A, Herzog W. Current Understanding of Residual Force Enhancement: Cross-Bridge Component and Non-Cross-Bridge Component. Int J Mol Sci 2019; 20:ijms20215479. [PMID: 31689920 PMCID: PMC6862632 DOI: 10.3390/ijms20215479] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2019] [Revised: 10/31/2019] [Accepted: 11/01/2019] [Indexed: 02/06/2023] Open
Abstract
Muscle contraction is initiated by the interaction between actin and myosin filaments. The sliding of actin filaments relative to myosin filaments is produced by cross-bridge cycling, which is governed by the theoretical framework of the cross-bridge theory. The cross-bridge theory explains well a number of mechanical responses, such as isometric and concentric contractions. However, some experimental observations cannot be explained with the cross-bridge theory; for example, the increased isometric force after eccentric contractions. The steady-state, isometric force after an eccentric contraction is greater than that attained in a purely isometric contraction at the same muscle length and same activation level. This well-acknowledged and universally observed property is referred to as residual force enhancement (rFE). Since rFE cannot be explained by the cross-bridge theory, alternative mechanisms for explaining this force response have been proposed. In this review, we introduce the basic concepts of sarcomere length non-uniformity and titin elasticity, which are the primary candidates that have been used for explaining rFE, and discuss unresolved problems regarding these mechanisms, and how to proceed with future experiments in this exciting area of research.
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Affiliation(s)
- Atsuki Fukutani
- Faculty of Sport and Health Science, Ritsumeikan University, 1-1-1 Noji-higashi, Kusatsu, Shiga 525-8577, Japan.
| | - Walter Herzog
- Faculty of Kinesiology, The University of Calgary, 2500 University Drive, NW, Calgary, AB T2N 1N4, Canada.
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37
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Nishikawa K, Dutta S, DuVall M, Nelson B, Gage MJ, Monroy JA. Calcium-dependent titin-thin filament interactions in muscle: observations and theory. J Muscle Res Cell Motil 2019; 41:125-139. [PMID: 31289970 DOI: 10.1007/s10974-019-09540-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Accepted: 07/04/2019] [Indexed: 10/26/2022]
Abstract
Gaps in our understanding of muscle mechanics demonstrate that the current model is incomplete. Increasingly, it appears that a role for titin in active muscle contraction might help to fill these gaps. While such a role for titin is increasingly accepted, the underlying molecular mechanisms remain unclear. The goals of this paper are to review recent studies demonstrating Ca2+-dependent interactions between N2A titin and actin in vitro, to explore theoretical predictions of muscle behavior based on this interaction, and to review experimental data related to the predictions. In a recent study, we demonstrated that Ca2+ increases the association constant between N2A titin and F-actin; that Ca2+ increases rupture forces between N2A titin and F-actin; and that Ca2+ and N2A titin reduce sliding velocity of F-actin and reconstituted thin filaments in motility assays. Preliminary data support a role for Ig83, but other Ig domains in the N2A region may also be involved. Two mechanical consequences are inescapable if N2A titin binds to thin filaments in active muscle sarcomeres: (1) the length of titin's freely extensible I-band should decrease upon muscle activation; and (2) binding between N2A titin and thin filaments should increase titin stiffness in active muscle. Experimental observations demonstrate that these properties characterize wild type muscles, but not muscles from mdm mice with a small deletion in N2A titin, including part of Ig83. Given the new in vitro evidence for Ca2+-dependent binding between N2A titin and actin, it is time for skepticism to give way to further investigation.
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Affiliation(s)
- Kiisa Nishikawa
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, 86011-4185, USA.
| | - Samrat Dutta
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, 86011-4185, USA
| | - Michael DuVall
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, 86011-4185, USA.,Edgewise Therapeutics Inc, 3415 Colorado Ave, Boulder, CO, 80303, USA
| | - Brent Nelson
- Department of Mechanical Engineering, Northern Arizona University, Flagstaff, AZ, 86011-15600, USA
| | - Matthew J Gage
- Chemistry Department, University of Massachusetts at Lowell, Lowell, MA, 01854, USA
| | - Jenna A Monroy
- W. M. Keck Science Center, Claremont Colleges, Claremont, CA, 91711-5916, USA
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38
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Abstract
Relaxed skeletal muscle has an inbuilt resistance to movement. In particular, the resistance manifests itself as a substantial stiffness for small movements. The stiffness is impermanent, because it forms only when the muscle is stationary for some time and is reduced upon active or passive movement. Because the resistance to movement increases with time at rest and is reduced by movement, this behavior has become known as muscle thixotropy. In this short review, we describe the phenomenon of thixotropy and illustrate its significance in postural control with particular emphasis on human standing. We show how thixotropy came to be unambiguously associated with muscle mechanics and we review present knowledge of the molecular basis of thixotropic behavior. Specifically, we examine how recent knowledge about titin, and about the control of cross-bridge cycling, has impacted on the role of non-cross-bridge mechanisms and cross-bridge mechanisms in explaining thixotropy. We describe how thixotropic changes in muscle stiffness that occur during transitions from posture to movement can be tracked by analyzing physiological tremor. Finally, because skeletal muscle contains sensory receptors, and because some of these receptors are themselves thixotropic, we outline some of the consequences of muscle thixotropy for proprioception.
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Affiliation(s)
- Martin Lakie
- School of Sport, Exercise and Rehabilitation, University of Birmingham , Birmingham , United Kingdom
| | - Kenneth S Campbell
- Department of Physiology, College of Medicine, University of Kentucky , Lexington, Kentucky
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Holt NC. Beyond bouncy gaits: The role of multiscale compliance in skeletal muscle performance. JOURNAL OF EXPERIMENTAL ZOOLOGY PART 2019; 333:50-59. [DOI: 10.1002/jez.2261] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 01/15/2019] [Accepted: 03/05/2019] [Indexed: 01/21/2023]
Affiliation(s)
- Natalie C. Holt
- Department of Biological Sciences; Northern Arizona University; Flagstaff Arizona
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40
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Ahn AN, Konow N, Tijs C, Biewener AA. Different Segments within Vertebrate Muscles Can Operate on Different Regions of Their Force-Length Relationships. Integr Comp Biol 2019; 58:219-231. [PMID: 29889253 DOI: 10.1093/icb/icy040] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
To relate in vivo behavior of fascicle segments within a muscle to their in vitro force-length relationships, we examined the strain behavior of paired segments within each of three vertebrate muscles. After determining in vivo muscle activity patterns and length changes of in-series segments within the semimembranosus muscle (SM) in the American Toad (Bufo americanus) during hopping and within the sternohyoid (SH) muscle in the rat (Rattus rattus) during swallowing, and of spatially separated fascicles within the medial gastrocnemius (MG) muscle in the rat during trotting, we measured their corresponding in vitro (toad) or in situ (rat) force-length relationships (FLRs). For all three muscles, in vivo strain heterogeneity lasted for about 36-57% of the behavior cycle, during which one segment or fascicle shortened while the other segment or fascicle simultaneously lengthened. In the toad SM, the proximal segment shortened from the descending limb across the plateau of its FLR from 1.12 to 0.91 of its optimal length (Lo), while the distal segment lengthened (by 0.04 ± 0.04 Lo) before shortening down the ascending limb from 0.94 to 0.83 Lo. In the rat SH muscle, the proximal segment tended to shorten on its ascending limb from 0.90 to 0.85 Lo while the distal segment tended to lengthen across Lo (0.96-1.12 Lo). In the rat MG muscle, in vivo strains of proximal fascicles ranged from 0.72 to 1.02 Lo, while the distal fascicles ranged from 0.88 to 1.11 Lo. Even though the timing of muscle activation patterns were similar between segments, the heterogeneous strain patterns of fascicle segments measured in vivo coincided with different operating ranges across their FLRs simultaneously, implying differences in force-velocity behavior as well. The three vertebrate skeletal muscles represent a diversity of fiber architectures and functions and suggest that patterns of in vivo contractile strain and the operating range over the FLR in one muscle region does not necessarily represent other regions within the same muscle.
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Affiliation(s)
- A N Ahn
- Concord Field Station, MCZ, Harvard University, 100 Old Causeway Road, Bedford, MA 01730, USA.,Department of Biology, Harvey Mudd College, 301 Platt Blvd, Claremont, CA 91711, USA
| | - N Konow
- Concord Field Station, MCZ, Harvard University, 100 Old Causeway Road, Bedford, MA 01730, USA.,Department of Biological Sciences, UMass Lowell, Lowell, MA 01854, USA
| | - C Tijs
- Concord Field Station, MCZ, Harvard University, 100 Old Causeway Road, Bedford, MA 01730, USA
| | - A A Biewener
- Concord Field Station, MCZ, Harvard University, 100 Old Causeway Road, Bedford, MA 01730, USA
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41
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Holt NC, Williams CD. Can Strain Dependent Inhibition of Cross-Bridge Binding Explain Shifts in Optimum Muscle Length? Integr Comp Biol 2018; 58:174-185. [PMID: 29873724 PMCID: PMC6104710 DOI: 10.1093/icb/icy050] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Skeletal muscle force is generated by cross-bridge interactions between the overlapping contractile proteins, actin and myosin. The geometry of this overlap gives us the force-length relationship in which maximum isometric force is generated at an intermediate, optimum, length. However, the force-length relationship is not constant; optimum length increases with decreasing muscle activation. This effect is not predicted from actin-myosin overlap. Here we present evidence that this activation-dependent shift in optimum length may be due to a series compliance within muscles. As muscles generate force during fixed-end contractions, fibers shorten against series compliance until forces equilibrate and they become isometric. Shortening against series-compliance is proportional to activation, and creates conditions under which shortening-induced force depression may suppress full force development. Greater shortening will result in greater force depression. Hence, optimum length may decrease as activation rises due to greater fiber shortening. We discuss explanations of such history dependence, giving a review of previously proposed processes and suggesting a novel mechanistic explanation for the most likely candidate process based on tropomyosin kinetics. We suggest this mechanism could change the relationship between actin-myosin overlap and cross-bridge binding potential, not only depressing force at any given length, but also altering the relationship between force and length. This would have major consequences for our understanding of in vivo muscle performance.
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Affiliation(s)
- N C Holt
- Department of Biological Sciences, Northern Arizona University, S. San Francisco Street, Flagstaff, AZ 86011, USA
| | - C D Williams
- Allen Institute for Cell Science, 615 Westlake Ave N, Seattle, WA 98109, USA
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42
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Myers CM, Kim JS, Florian JP. Effects of repeated long-duration water immersions on skeletal muscle performance in well-trained male divers. Eur J Appl Physiol 2018; 118:2065-2076. [PMID: 30003382 DOI: 10.1007/s00421-018-3928-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Accepted: 06/30/2018] [Indexed: 11/26/2022]
Abstract
PURPOSE The objective of this study was to examine the effects of repeated long-duration water immersions (WI)s at 1.35 atmospheres absolute (ATA) on neuromuscular performance in load bearing and non-load bearing muscle groups. METHODS During a dive week (DW), fifteen well-trained male divers completed five consecutive 6-h resting dives with 18-h surface intervals while breathing compressed air at 1.35 ATA. Skeletal muscle performance assessments occurred immediately before and after each WI, and 24 and 72 h after the final WI. Exercise assessments included maximum voluntary isometric contraction (MVIC), maximal isokinetic (IK) contraction, maximum handgrip strength (MHG). Surface electromyography measured neuromuscular activation of the quadriceps, biceps brachii (BB), and brachioradialis. RESULTS MVIC torque of knee extensors and BB decreased by 6% (p = 0.001) and 2% (p = 0.014), respectively, by WI 3. Maximal IK torque of knee extensors increased by 11 and 5% post-WI on WIs 3 and 5 (p < 0.001) with greater neuromuscular activation post-WI than pre-WI (p < 0.001). Maximum IK elbow flexion torque did not change throughout the DW with BB neuromuscular activation greater post-WI than pre-WI (p < 0.001). MHG force output was 4% greater post-WI than pre-WI (p < 0.001) with increased brachioradialis activation through 72-h post-WI (p < 0.001). All muscle performance metrics returned baseline levels by 72-h post-WI. CONCLUSION Our findings indicate that repeated WIs caused noticeable decrements in neuromuscular activation and performance of load bearing muscles on WI 3 while full recovery was observed by 72-h post-WI.
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Affiliation(s)
- Christopher M Myers
- Department of Nutrition, Food and Exercise Sciences, Florida State University, Tallahassee, FL, USA
| | - Jeong-Su Kim
- Department of Nutrition, Food and Exercise Sciences, Florida State University, Tallahassee, FL, USA
| | - John P Florian
- Navy Experimental Diving Unit, 321 Bullfinch Rd., Panama City, FL, 32407, USA.
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43
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Aagaard P. Spinal and supraspinal control of motor function during maximal eccentric muscle contraction: Effects of resistance training. JOURNAL OF SPORT AND HEALTH SCIENCE 2018; 7:282-293. [PMID: 30356634 PMCID: PMC6189238 DOI: 10.1016/j.jshs.2018.06.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/28/2018] [Revised: 03/22/2018] [Accepted: 03/24/2018] [Indexed: 06/08/2023]
Abstract
Neuromuscular activity is suppressed during maximal eccentric (ECC) muscle contraction in untrained subjects owing to attenuated levels of central activation and reduced spinal motor neuron (MN) excitability indicated by reduced electromyography signal amplitude, diminished evoked H-reflex responses, increased autogenic MN inhibition, and decreased excitability in descending corticospinal motor pathways. Maximum ECC muscle force recorded during maximal voluntary contraction can be increased by superimposed electrical muscle stimulation only in untrained individuals and not in trained strength athletes, indicating that the suppression in MN activation is modifiable by resistance training. In support of this notion, maximum ECC muscle strength can be increased by use of heavy-load resistance training owing to a removed or diminished suppression in neuromuscular activity. Prolonged (weeks to months) of heavy-load resistance training results in increased H-reflex and V-wave responses during maximal ECC muscle actions along with marked gains in maximal ECC muscle strength, indicating increased excitability of spinal MNs, decreased presynaptic and/or postsynaptic MN inhibition, and elevated descending motor drive. Notably, the use of supramaximal ECC resistance training can lead to selectively elevated V-wave responses during maximal ECC contraction, demonstrating that adaptive changes in spinal circuitry function and/or gains in descending motor drive can be achieved during maximal ECC contraction in response to heavy-load resistance training.
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44
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Nguyen KD, Sharma N, Venkadesan M. Active Viscoelasticity of Sarcomeres. Front Robot AI 2018; 5:69. [PMID: 33500948 PMCID: PMC7805709 DOI: 10.3389/frobt.2018.00069] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2017] [Accepted: 05/25/2018] [Indexed: 11/13/2022] Open
Abstract
The perturbation response of muscle is important for the versatile, stable and agile control capabilities of animals. Muscle resists being stretched by developing forces in the passive tissues and in the active crossbridges. This review focuses on the active perturbation response of the sarcomere. The active response exhibits typical stress relaxation, and thus approximated by a Maxwell material that has a spring and dashpot arranged in series. The ratio of damping to stiffness in this approximation defines the relaxation timescale for dissipating stresses that are developed in the crossbridges due to external perturbations. Current understanding of sarcomeres suggests that stiffness varies nearly linearly with neural excitation, but not much is known about damping. But if both stiffness and damping have the same functional (linear or not) dependence on neural excitation, then the stress relaxation timescale cannot be varied depending on the demands of the task. This implies an unavoidable and biologically unrealistic trade-off between how freely the crossbridges can yield and dissipate stresses when stretched (injury avoidance in agile motions) vs. how long they can maintain perturbation-induced stresses and behave like a solid material (stiffness maintenance for stability). We hypothesize that muscle circumvents this trade-off by varying damping in a nonlinear manner with neural excitation, unlike stiffness that varies linearly. Testing this hypothesis requires new experimental and mathematical characterization of muscle mechanics, and also identifies new design goals for robotic actuators.
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Affiliation(s)
| | | | - Madhusudhan Venkadesan
- Department of Mechanical Engineering and Materials Science, Yale University, New Haven, CT, United States
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45
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Williams CD, Holt NC. Spatial Scale and Structural Heterogeneity in Skeletal Muscle Performance. Integr Comp Biol 2018; 58:163-173. [DOI: 10.1093/icb/icy057] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Affiliation(s)
- C D Williams
- Allen Institute for Cell Science, 615 Westlake Ave N, Seattle, WA 98109, USA
| | - N C Holt
- Department of Biology, Northern Arizona University, S. San Francisco Street, Flagstaff, AZ 86011, USA
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46
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Niess F, Fiedler GB, Schmid AI, Laistler E, Frass‐Kriegl R, Wolzt M, Moser E, Meyerspeer M. Dynamic multivoxel-localized 31 P MRS during plantar flexion exercise with variable knee angle. NMR IN BIOMEDICINE 2018; 31:e3905. [PMID: 29578260 PMCID: PMC6001778 DOI: 10.1002/nbm.3905] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Revised: 01/08/2018] [Accepted: 01/16/2018] [Indexed: 05/07/2023]
Abstract
Exercise studies investigating the metabolic response of calf muscles using 31 P MRS are usually performed with a single knee angle. However, during natural movement, the distribution of workload between the main contributors to force, gastrocnemius and soleus is influenced by the knee angle. Hence, it is of interest to measure the respective metabolic response of these muscles to exercise as a function of knee angle using localized spectroscopy. Time-resolved multivoxel 31 P MRS at 7 T was performed simultaneously in gastrocnemius medialis and soleus during rest, plantar flexion exercise and recovery in 12 healthy volunteers. This experiment was conducted with four different knee angles. PCr depletions correlated negatively with knee angle in gastrocnemius medialis, decreasing from 79±14 % (extended leg) to 35±23 %(∼40°), and positively in soleus, increasing from 20±21 % to 36±25 %; differences were significant. Linear correlations were found between knee angle and end-exercise PCr depletions in gastrocnemius medialis (R2 =0.8) and soleus (R2 =0.53). PCr recovery times and end-exercise pH changes that correlated with PCr depletion were consistent with the literature in gastrocnemius medialis and differences between knee angles were significant. These effects were less pronounced in soleus and not significant for comparable PCr depletions. Maximum oxidative capacity calculated for all knee angles was in excellent agreement with the literature and showed no significant changes between different knee angles. In conclusion, these findings confirm that plantar flexion exercise with a straight leg is a suitable paradigm, when data are acquired from gastrocnemius only (using either localized MRS or small surface coils), and that activation of soleus requires the knee to be flexed. The present study comprises a systematic investigation of the effects of the knee angle on metabolic parameters, measured with dynamic multivoxel 31 P MRS during muscle exercise and recovery, and the findings should be used in future study design.
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Affiliation(s)
- Fabian Niess
- Center for Medical Physics and Biomedical EngineeringMedical University of ViennaAustria
- Highfield MR CenterMedical University of ViennaAustria
| | - Georg B. Fiedler
- Center for Medical Physics and Biomedical EngineeringMedical University of ViennaAustria
- Highfield MR CenterMedical University of ViennaAustria
| | - Albrecht I. Schmid
- Center for Medical Physics and Biomedical EngineeringMedical University of ViennaAustria
- Highfield MR CenterMedical University of ViennaAustria
| | - Elmar Laistler
- Center for Medical Physics and Biomedical EngineeringMedical University of ViennaAustria
- Highfield MR CenterMedical University of ViennaAustria
| | - Roberta Frass‐Kriegl
- Center for Medical Physics and Biomedical EngineeringMedical University of ViennaAustria
- Highfield MR CenterMedical University of ViennaAustria
| | - Michael Wolzt
- Department of Clinical PharmacologyMedical University of ViennaAustria
| | - Ewald Moser
- Center for Medical Physics and Biomedical EngineeringMedical University of ViennaAustria
- Highfield MR CenterMedical University of ViennaAustria
| | - Martin Meyerspeer
- Center for Medical Physics and Biomedical EngineeringMedical University of ViennaAustria
- Highfield MR CenterMedical University of ViennaAustria
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47
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Tahir U, Hessel AL, Lockwood ER, Tester JT, Han Z, Rivera DJ, Covey KL, Huck TG, Rice NA, Nishikawa KC. Case Study: A Bio-Inspired Control Algorithm for a Robotic Foot-Ankle Prosthesis Provides Adaptive Control of Level Walking and Stair Ascent. Front Robot AI 2018; 5:36. [PMID: 33500922 PMCID: PMC7805871 DOI: 10.3389/frobt.2018.00036] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Accepted: 03/19/2018] [Indexed: 11/30/2022] Open
Abstract
Powered ankle-foot prostheses assist users through plantarflexion during stance and dorsiflexion during swing. Provision of motor power permits faster preferred walking speeds than passive devices, but use of active motor power raises the issue of control. While several commercially available algorithms provide torque control for many intended activities and variations of terrain, control approaches typically exhibit no inherent adaptation. In contrast, muscles adapt instantaneously to changes in load without sensory feedback due to the intrinsic property that their stiffness changes with length and velocity. We previously developed a “winding filament” hypothesis (WFH) for muscle contraction that accounts for intrinsic muscle properties by incorporating the giant titin protein. The goals of this study were to develop a WFH-based control algorithm for a powered prosthesis and to test its robustness during level walking and stair ascent in a case study of two subjects with 4–5 years of experience using a powered prosthesis. In the WFH algorithm, ankle moments produced by virtual muscles are calculated based on muscle length and activation. Net ankle moment determines the current applied to the motor. Using this algorithm implemented in a BiOM T2 prosthesis, we tested subjects during level walking and stair ascent. During level walking at variable speeds, the WFH algorithm produced plantarflexion angles (range = −8 to −19°) and ankle moments (range = 1 to 1.5 Nm/kg) similar to those produced by the BiOM T2 stock controller and to people with no amputation. During stair ascent, the WFH algorithm produced plantarflexion angles (range −15 to −19°) that were similar to persons with no amputation and were ~5 times larger on average at 80 steps/min than those produced by the stock controller. This case study provides proof-of-concept that, by emulating muscle properties, the WFH algorithm provides robust, adaptive control of level walking at variable speed and stair ascent with minimal sensing and no change in parameters.
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Affiliation(s)
- Uzma Tahir
- Center for Bioengineering Innovation and Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, United States
| | - Anthony L Hessel
- Center for Bioengineering Innovation and Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, United States
| | - Eric R Lockwood
- Department of Mechanical Engineering, Northern Arizona University, Flagstaff, AZ, United States
| | - John T Tester
- Department of Mechanical Engineering, Northern Arizona University, Flagstaff, AZ, United States
| | - Zhixiu Han
- BionX Medical Technologies, Inc., Bedford, MA, United States
| | - Daniel J Rivera
- Department of Mechanical Engineering, Northern Arizona University, Flagstaff, AZ, United States
| | - Kaitlyn L Covey
- Department of Mechanical Engineering, Northern Arizona University, Flagstaff, AZ, United States
| | - Thomas G Huck
- Center for Bioengineering Innovation and Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, United States
| | - Nicole A Rice
- Center for Bioengineering Innovation and Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, United States
| | - Kiisa C Nishikawa
- Center for Bioengineering Innovation and Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, United States
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Ivanenko Y, Gurfinkel VS. Human Postural Control. Front Neurosci 2018; 12:171. [PMID: 29615859 PMCID: PMC5869197 DOI: 10.3389/fnins.2018.00171] [Citation(s) in RCA: 192] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Accepted: 03/05/2018] [Indexed: 12/21/2022] Open
Abstract
From ancient Greece to nowadays, research on posture control was guided and shaped by many concepts. Equilibrium control is often considered part of postural control. However, two different levels have become increasingly apparent in the postural control system, one level sets a distribution of tonic muscle activity (“posture”) and the other is assigned to compensate for internal or external perturbations (“equilibrium”). While the two levels are inherently interrelated, both neurophysiological and functional considerations point toward distinct neuromuscular underpinnings. Disturbances of muscle tone may in turn affect movement performance. The unique structure, specialization and properties of skeletal muscles should also be taken into account for understanding important peripheral contributors to postural regulation. Here, we will consider the neuromechanical basis of habitual posture and various concepts that were rather influential in many experimental studies and mathematical models of human posture control.
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Affiliation(s)
- Yury Ivanenko
- Laboratory of Neuromotor Physiology, IRCCS Fondazione Santa Lucia, Rome, Italy
| | - Victor S Gurfinkel
- Biomedical Engineering Department, Oregon Health and Science University, Portland, OR, United States
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Flück M, Bosshard R, Lungarella M. Cardiovascular and Muscular Consequences of Work-Matched Interval-Type of Concentric and Eccentric Pedaling Exercise on a Soft Robot. Front Physiol 2017; 8:640. [PMID: 28912726 PMCID: PMC5583980 DOI: 10.3389/fphys.2017.00640] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Accepted: 08/15/2017] [Indexed: 11/23/2022] Open
Abstract
Eccentric types of endurance exercise are an acknowledged alternative to conventional concentric types of exercise rehabilitation for the cardiac patient, because they reduce cardiorespiratory strain due to a lower metabolic cost of producing an equivalent mechanical output. The former contention has not been tested in a power- and work-matched situation of interval-type exercise under identical conditions because concentric and eccentric types of exercise pose specific demands on the exercise machinery, which are not fulfilled in current practice. Here we tested cardiovascular and muscular consequences of work-matched interval-type of leg exercise (target workload of 15 sets of 1-min bipedal cycles of knee extension and flexion at 30 rpm with 17% of maximal concentric power) on a soft robotic device in healthy subjects by concomitantly monitoring respiration, blood glucose and lactate, and power during exercise and recovery. We hypothesized that interval-type of eccentric exercise lowers strain on glucose-related aerobic metabolism compared to work-matched concentric exercise, and reduces cardiorespiratory strain to levels being acceptable for the cardiac patient. Eight physically active male subjects (24.0 years, 74.7 kg, 3.4 L O2 min−1), which power and endurance performance was extensively characterized, completed the study, finalizing 12 sets on average. Average performance was similar during concentric and eccentric exercise (p = 0.75) but lower than during constant load endurance exercise on a cycle ergometer at 75% of peak aerobic power output (126 vs. 188 Watt) that is recommended for improving endurance capacity. Peak oxygen uptake (−17%), peak ventilation (−23%), peak cardiac output (−16%), and blood lactate (−37%) during soft robotic exercise were lower during eccentric than concentric exercise. Glucose was 8% increased after eccentric exercise when peak RER was 12% lower than during concentric exercise. Muscle power and RFD were similarly reduced after eccentric and concentric exercise. The results highlight that the deployed interval-type of eccentric leg exercise reduces metabolic strain of the cardiovasculature and muscle compared to concentric exercise, to recommended levels for cardio-rehabilitation (i.e., 50–70% of peak heart rate). Increases in blood glucose concentration indicate that resistance to contraction-induced glucose uptake after the deployed eccentric protocol is unrelated to muscle fatigue.
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Affiliation(s)
- Martin Flück
- Department of Orthopedics, University of ZurichZurich, Switzerland.,Zurich Center for Integrative Human Physiology, University of ZurichZurich, Switzerland
| | - Rebekka Bosshard
- Department of Orthopedics, University of ZurichZurich, Switzerland.,Department of Health Sciences and Technology, ETH ZurichZurich, Switzerland
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