1
|
Pineau A, Martin A, Lepers R, Papaiordanidou M. Effect of combined electrical stimulation and brief muscle lengthening on torque development. J Appl Physiol (1985) 2024; 136:844-852. [PMID: 38357725 DOI: 10.1152/japplphysiol.00671.2023] [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: 09/19/2023] [Revised: 01/31/2024] [Accepted: 02/13/2024] [Indexed: 02/16/2024] Open
Abstract
This study aimed to evaluate torque production in response to the application of a brief muscle lengthening during neuromuscular electrical stimulation (NMES) applied over the posterior tibial nerve. Fifteen participants took part in three experimental sessions, where wide-pulse NMES delivered at 20 and 100 Hz (pulse duration of 1 ms applied during 15 s at an intensity evoking 5-10% of maximal voluntary contraction) was either applied alone (NMES condition) or in combination with a muscle lengthening at three distinct speeds (60, 180, or 300°/s; NMES + LEN condition). The torque-time integral (TTI) and the muscle activity following the stimulation trains [sustained electromyography (EMG)] were calculated for each condition. Results show that TTI and sustained EMG activity were higher for the NMES + LEN condition only when using 100-Hz stimulation, regardless of the lengthening speed (P = 0.029 and P = 0.007 for the two parameters, respectively). This indicates that superimposing a muscle lengthening to high-frequency NMES can enhance the total torque production, partly due to neural mechanisms, as evidenced by the higher sustained EMG activity. This finding has potential clinical relevance, especially when it comes to finding ways to enhance torque production to optimize the effectiveness of NMES training programs.NEW & NOTEWORTHY This study showed, for the first time, that the combined application of a brief muscle lengthening and wide-pulse neuromuscular electrical stimulation (NMES) delivered over the posterior tibial nerve can entail increased torque production as compared with the sole application of NMES. This observation, present only for high stimulation frequencies (100 Hz) and independently of the lengthening speed, is attributed to neural mechanisms, most probably related to increased afferents' solicitation, although muscular phenomena cannot be excluded.
Collapse
Affiliation(s)
- Antoine Pineau
- INSERM UMR1093-CAPS, Université Bourgogne, UFR des Sciences du Sport, Dijon, France
| | - Alain Martin
- INSERM UMR1093-CAPS, Université Bourgogne, UFR des Sciences du Sport, Dijon, France
| | - Romuald Lepers
- INSERM UMR1093-CAPS, Université Bourgogne, UFR des Sciences du Sport, Dijon, France
| | - Maria Papaiordanidou
- INSERM UMR1093-CAPS, Université Bourgogne, UFR des Sciences du Sport, Dijon, France
| |
Collapse
|
2
|
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.
Collapse
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
| |
Collapse
|
3
|
Simha SN, Ting LH. Intrafusal cross-bridge dynamics shape history-dependent muscle spindle responses to stretch. Exp Physiol 2024; 109:112-124. [PMID: 37428622 PMCID: PMC10776813 DOI: 10.1113/ep090767] [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: 12/04/2022] [Accepted: 06/23/2023] [Indexed: 07/12/2023]
Abstract
Computational models can be critical to linking complex properties of muscle spindle organs to the sensory information that they encode during behaviours such as postural sway and locomotion where few muscle spindle recordings exist. Here, we augment a biophysical muscle spindle model to predict the muscle spindle sensory signal. Muscle spindles comprise several intrafusal muscle fibres with varied myosin expression and are innervated by sensory neurons that fire during muscle stretch. We demonstrate how cross-bridge dynamics from thick and thin filament interactions affect the sensory receptor potential at the spike initiating region. Equivalent to the Ia afferent's instantaneous firing rate, the receptor potential is modelled as a linear sum of the force and rate change of force (yank) of a dynamic bag1 fibre and the force of a static bag2/chain fibre. We show the importance of inter-filament interactions in (i) generating large changes in force at stretch onset that drive initial bursts and (ii) faster recovery of bag fibre force and receptor potential following a shortening. We show how myosin attachment and detachment rates qualitatively alter the receptor potential. Finally, we show the effect of faster recovery of receptor potential on cyclic stretch-shorten cycles. Specifically, the model predicts history-dependence in muscle spindle receptor potentials as a function of inter-stretch interval (ISI), pre-stretch amplitude and the amplitude of sinusoidal stretches. This model provides a computational platform for predicting muscle spindle response in behaviourally relevant stretches and can link myosin expression seen in healthy and diseased intrafusal muscle fibres to muscle spindle function.
Collapse
Affiliation(s)
- Surabhi N. Simha
- Wallace H. Coulter Department of Biomedical EngineeringEmory University and The Georgia Institute of TechnologyAtlantaGeorgiaUSA
| | - Lena H. Ting
- Wallace H. Coulter Department of Biomedical EngineeringEmory University and The Georgia Institute of TechnologyAtlantaGeorgiaUSA
- Department of Rehabilitation Medicine, Division of Physical TherapyEmory UniversityAtlantaGeorgiaUSA
| |
Collapse
|
4
|
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. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.08.539853. [PMID: 37215007 PMCID: PMC10197546 DOI: 10.1101/2023.05.08.539853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
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 make 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-hold-release, and triangular stretches were analyzed to examine potential changes in muscle spindle instantaneous firing rates (IFRs) in locomotor- and perturbation-like stretches as well as 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 firing rates were reduced and IFR was strongly correlated with fascicle velocity. During ramp stretches, SEEs reduced the dynamic and static responses of the spindle during lengthening but had no effect on initial bursts at the onset of stretch. 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 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 and velocity.
Collapse
Affiliation(s)
| | - Jacob D Stephens
- Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of Technology
| | - Surabhi N Simha
- Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of Technology
| | - Leo Wood
- School of Physics, Georgia Institute of Technology
| | - Paul Nardelli
- School of Biological Sciences, Georgia Institute of Technology
| | - Timothy C Cope
- Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of Technology
- School of Biological Sciences, Georgia Institute of Technology
| | - Gregory S Sawicki
- Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of Technology
- Woodruff School of Mechanical Engineering, Georgia Institute of Technology
| | - Lena H Ting
- Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of Technology
- Department of Rehabilitation Medicine, Emory University
| |
Collapse
|
5
|
Kwak ST, Chang YH. Fascicle dynamics of the tibialis anterior muscle reflect whole-body walking economy. Sci Rep 2023; 13:4660. [PMID: 36949112 PMCID: PMC10033896 DOI: 10.1038/s41598-023-31501-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Accepted: 03/13/2023] [Indexed: 03/24/2023] Open
Abstract
Humans can inherently adapt their gait pattern in a way that minimizes the metabolic cost of transport, or walking economy, within a few steps, which is faster than any known direct physiological sensor of metabolic energy. Instead, walking economy may be indirectly sensed through mechanoreceptors that correlate with the metabolic cost per step to make such gait adaptations. We tested whether velocity feedback from tibialis anterior (TA) muscle fascicles during the early stance phase of walking could potentially act to indirectly sense walking economy. As participants walked within a range of steady-state speeds and step frequencies, we observed that TA fascicles lengthen on almost every step. Moreover, the average peak fascicle velocity experienced during lengthening reflected the metabolic cost of transport of the given walking condition. We observed that the peak TA muscle activation occurred earlier than could be explained by a short latency reflex response. The activation of the TA muscle just prior to heel strike may serve as a prediction of the magnitude of the ground collision and the associated energy exchange. In this scenario, any unexpected length change experienced by the TA fascicle would serve as an error signal to the nervous system and provide additional information about energy lost per step. Our work helps provide a biomechanical framework to understand the possible neural mechanisms underlying the rapid optimization of walking economy.
Collapse
Affiliation(s)
- Samuel T Kwak
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA.
| | - Young-Hui Chang
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA
| |
Collapse
|
6
|
Agonist-antagonist muscle strain in the residual limb preserves motor control and perception after amputation. COMMUNICATIONS MEDICINE 2022; 2:97. [PMID: 35942078 PMCID: PMC9356003 DOI: 10.1038/s43856-022-00162-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Accepted: 07/22/2022] [Indexed: 12/04/2022] Open
Abstract
Background Elucidating underlying mechanisms in subject-specific motor control and perception after amputation could guide development of advanced surgical and neuroprosthetic technologies. In this study, relationships between preserved agonist-antagonist muscle strain within the residual limb and preserved motor control and perception capacity are investigated. Methods Fourteen persons with unilateral transtibial amputations spanning a range of ages, etiologies, and surgical procedures underwent evaluations involving free-space mirrored motions of their lower limbs. Research has shown that varied motor control in biologically intact limbs is executed by the activation of muscle synergies. Here, we assess the naturalness of phantom joint motor control postamputation based on extracted muscle synergies and their activation profiles. Muscle synergy extraction, degree of agonist-antagonist muscle strain, and perception capacity are estimated from electromyography, ultrasonography, and goniometry, respectively. Results Here, we show significant positive correlations (P < 0.005–0.05) between sensorimotor responses and residual limb agonist-antagonist muscle strain. Identified trends indicate that preserving even 20–26% of agonist-antagonist muscle strain within the residuum compared to a biologically intact limb is effective in preserving natural motor control postamputation, though preserving limb perception capacity requires more (61%) agonist-antagonist muscle strain preservation. Conclusions The results suggest that agonist-antagonist muscle strain is a characteristic, readily ascertainable residual limb structural feature that can help explain variability in amputation outcome, and agonist-antagonist muscle strain preserving surgical amputation strategies are one way to enable more effective and biomimetic sensorimotor control postamputation. People who undergo limb amputation can have issues with controlling movement and perception of residual limbs. This, in turn, can impact the success of neuroprosthetic strategies, which use signals from the body to control a prosthetic limb. Here, we wanted to understand how sensory signals within the muscle help to preserve movement and limb perception following amputation. We used ultrasound imaging and other methods to measure muscle activity and limb perception in fourteen people who have undergone lower limb amputations. We show that the level at which the relationship between pairs of related muscles is preserved is associated with more natural control of limb movement after amputation. Developing surgical techniques that preserve this relationship may help people living with amputations to naturally perceive and control their residual limbs, and ultimately may improve controllability of assistive prosthetic devices. Song et al. study the relationship between agonist-antagonist muscle strain (AMS) and motor control and perception in lower limb amputees, with some receiving a myoneural interface intervention. The authors report that the degree of AMS within the residual limb is associated with preserved motor control and perception.
Collapse
|
7
|
The force-generation capacity of the tibialis anterior muscle at different muscle-tendon lengths depends on its motor unit contractile properties. Eur J Appl Physiol 2021; 122:317-330. [PMID: 34677625 PMCID: PMC8783895 DOI: 10.1007/s00421-021-04829-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 10/07/2021] [Indexed: 11/17/2022]
Abstract
Purpose Muscle–tendon length can influence central and peripheral motor unit (MU) characteristics, but their interplay is unknown. This study aims to explain the effect of muscle length on MU firing and contractile properties by applying deconvolution of high-density surface EMG (HDEMG), and torque signals on the same MUs followed at different lengths during voluntary contractions. Methods Fourteen participants performed isometric ankle dorsiflexion at 10% and 20% of the maximal voluntary torque (MVC) at short, optimal, and long muscle lengths (90°, 110°, and 130° ankle angles, respectively). HDEMG signals were recorded from the tibialis anterior, and MUs were tracked by cross-correlation of MU action potentials across ankle angles and torques. Torque twitch profiles were estimated using model-based deconvolution of the torque signal based on composite MU spike trains. Results Mean discharge rate of matched motor units was similar across all muscle lengths (P = 0.975). Interestingly, the increase in mean discharge rate of MUs matched from 10 to 20% MVC force levels at the same ankle angle was smaller at 110° compared with the other two ankle positions (P = 0.003), and the phenomenon was explained by a greater increase in twitch torque at 110° compared to the shortened and lengthened positions (P = 0.002). This result was confirmed by the deconvolution of electrically evoked contractions at different stimulation frequencies and muscle–tendon lengths. Conclusion Higher variations in MU twitch torque at optimal muscle lengths likely explain the greater force-generation capacity of muscles in this position.
Collapse
|
8
|
Kirk EA, Gilmore KJ, Rice CL. Anconeus motor unit firing rates during isometric and muscle-shortening contractions comparing young and very old adults. J Neurophysiol 2021; 126:1122-1136. [PMID: 34495770 DOI: 10.1152/jn.00219.2021] [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: 11/22/2022] Open
Abstract
With effects of aging, voluntary neural drive to the muscle, measured as motor unit (MU) firing rate, is lower in older adults during sustained isometric contractions compared with young adults, but differences remain unknown during limb movements. Therefore, our purpose was to compare MU firing rates during both isometric and shortening contractions between two adult age groups. We analyzed intramuscular electromyography of single-MU recordings in the anconeus muscle of young (n = 8, 19-33 yr) and very old (n = 13, 78-93 yr) male adults during maximal voluntary contractions (MVCs). In sustained isometric and muscle-shortening contractions during limb movement, MU trains were linked with elbow joint kinematic parameters throughout the contraction time course. The older group was 33% weaker and 10% slower during movements than the young group (P < 0.01). In isometric contractions, median firing rates were 42% lower (P < 0.01) in the older group (18 Hz) compared with the young group (31 Hz), but during shortening contractions firing rates were higher for both age groups and not statistically different between groups. As a function of contraction time, firing rates at MU recruitment threshold were 39% lower in the older group, but the firing rate decrease was attenuated threefold throughout shortening contraction compared with the young group. At the single-MU level, age-related differences during isometric contractions (i.e., pre-movement initiation) do not remain constant throughout movement that comprises greater effects of muscle shortening. Results indicate that neural drive is task dependent and during movement in older adults it is decreased minimally.NEW & NOTEWORTHY Changes of neural drive to the muscle with adult aging, measured as motor unit firing rates during limb movements, are unknown. Throughout maximal voluntary efforts we found that, in comparison with young adults, firing rates were lower during isometric contraction in older adults but not different during elbow extension movements. Despite the older group being ∼33% weaker across contractions, their muscles can receive neural drive during movements that are similar to that of younger adults.
Collapse
Affiliation(s)
- Eric A Kirk
- School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, London, Ontario, Canada
| | - Kevin J Gilmore
- Department of Surgery, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Charles L Rice
- School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, London, Ontario, Canada.,Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Ontario, Canada
| |
Collapse
|
9
|
Khurram OU, Negro F, Heckman CJ, Thompson CK. Estimates of persistent inward currents in tibialis anterior motor units during standing ramped contraction tasks in humans. J Neurophysiol 2021; 126:264-274. [PMID: 34133235 DOI: 10.1152/jn.00144.2021] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Persistent inward currents (PICs) play an essential role in setting motor neuron gain and shaping motor unit firing patterns. Estimates of PICs in humans can be made using the paired motor unit analysis technique, which quantifies the difference in discharge rate of a lower threshold motor unit at the recruitment onset and offset of a higher threshold motor unit (ΔF). Because PICs are highly dependent on the level of neuromodulatory drive, ΔF represents an estimate of level of neuromodulation at the level of the spinal cord. Most of the estimates of ΔF are performed under constrained, isometric, seated conditions. In the present study, we used high-density surface EMG arrays to discriminate motor unit firing patterns during isometric seated conditions with torque or EMG visual feedback and during unconstrained standing anterior-to-posterior movements with root mean square EMG visual feedback. We were able to apply the paired motor unit analysis technique to the decomposed motor units in each of the three conditions. We hypothesized that ΔF would be higher during unconstrained standing anterior-to-posterior movements compared with the seated conditions, reflecting an increase in the synaptic input to motoneurons drive while standing. In agreement with previous work, we found that there was no evidence of a difference in ΔF between the seated and standing postures, although slight differences in the initial and peak discharge rates were observed. Taken together, our results suggest that both the standing and seated postures are likely not sufficiently different, both being "upright" postures, to result in large changes in neuromodulatory drive.NEW & NOTEWORTHY In the present study, we show that the discharge rate of a lower threshold motor unit at the recruitment onset and offset of a higher threshold motor unit (ΔF) is similar between standing and seated conditions in human tibialis anterior motor units, suggesting that at least for these two upright postures neuromodulatory drive is similar. We also highlight a proposed technological development in using high-density EMG arrays for real-time muscle activity feedback to accomplish standing ramped contraction tasks and demonstrate the validity of the paired motor unit analysis technique during these conditions.
Collapse
Affiliation(s)
- Obaid U Khurram
- Department of Physiology, Northwestern University, Chicago, Illinois.,Department of Physical Therapy and Human Movement Sciences, Northwestern University, Chicago, Illinois
| | - Francesco Negro
- Department of Clinical and Experimental Sciences, Università degli Studi di Brescia, Brescia, Italy
| | - C J Heckman
- Department of Physiology, Northwestern University, Chicago, Illinois.,Department of Physical Therapy and Human Movement Sciences, Northwestern University, Chicago, Illinois.,Department of Physical Medicine and Rehabilitation, Shirley Ryan AbilityLab, Chicago, Illinois
| | - Christopher K Thompson
- Department of Health and Rehabilitation Sciences, Temple University, Philadelphia, Pennsylvania
| |
Collapse
|
10
|
Raiteri BJ, Beller R, Hahn D. Biceps Femoris Long Head Muscle Fascicles Actively Lengthen During the Nordic Hamstring Exercise. Front Sports Act Living 2021; 3:669813. [PMID: 34179775 PMCID: PMC8219857 DOI: 10.3389/fspor.2021.669813] [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: 02/19/2021] [Accepted: 04/21/2021] [Indexed: 11/28/2022] Open
Abstract
Current debate exists around whether a presumed eccentric exercise, the Nordic hamstring exercise (NHE), actually causes active hamstring muscle lengthening. This is because of the decoupling that can occur between the muscle fascicle and muscle-tendon unit (MTU) length changes in relatively compliant human lower-limb MTUs, which results in MTU lengthening not necessarily causing muscle fascicle lengthening. This missing knowledge complicates the interpretation of why the NHE is effective at reducing running-related hamstring muscle injury risk in athletes previously unfamiliar with performing this exercise. The purpose of the study was therefore to investigate if the most-commonly injured hamstring muscle, the biceps femoris long head (BF), exhibits active muscle lengthening (i.e. an eccentric muscle action) during the NHE up until peak force in Nordic novices. External reaction force at the ankle, knee flexion angle, and BF and semitendinosus muscle activities were recorded from the left leg of 14 participants during the NHE. Simultaneously, BF muscle architecture was imaged using B-mode ultrasound imaging, and muscle architecture changes were tracked using two different tracking algorithms. From ~85 to 100% of peak NHE force, both tracking algorithms detected that BF muscle fascicles (n = 10) significantly lengthened (p < 0.01) and had a mean positive lengthening velocity (p ≤ 0.02), while knee extension velocity remained positive (17°·s−1) over knee flexion angles from 53 to 37° and a duration of 1.6 s. Despite some individual cases of brief isometric fascicle behavior and brief fascicle shortening during BF MTU lengthening, the predominant muscle action was eccentric under a relatively high muscle activity level (59% of maximum). Eccentric hamstring muscle action therefore does occur during the NHE in relatively strong (429 N) Nordic novices, which might contribute to the increase in resting BF muscle fascicle length and reduction in running-related injury risk, which have previously been reported following NHE training. Whether an eccentric BF muscle action occurs in individuals accustomed to the NHE remains to be tested.
Collapse
Affiliation(s)
- Brent J Raiteri
- Human Movement Science, Faculty of Sport Science, Ruhr University Bochum, Bochum, Germany
| | - Ronja Beller
- Human Movement Science, Faculty of Sport Science, Ruhr University Bochum, Bochum, Germany.,Department of Pediatric Hematology/Oncology, Center for Child and Adolescent Medicine, Essen University Hospital, Essen, Germany
| | - Daniel Hahn
- Human Movement Science, Faculty of Sport Science, Ruhr University Bochum, Bochum, Germany.,School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, QLD, Australia
| |
Collapse
|
11
|
Macefield VG. The roles of mechanoreceptors in muscle and skin in human proprioception. CURRENT OPINION IN PHYSIOLOGY 2021. [DOI: 10.1016/j.cophys.2021.03.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
|
12
|
Datoussaid M, El Khalouqi H, Dahm C, Guissard N, Baudry S. Passive torque influences the Hoffmann reflex pathway during the loading and unloading phases of plantar flexor muscles stretching. Physiol Rep 2021; 9:e14834. [PMID: 33932117 PMCID: PMC8087990 DOI: 10.14814/phy2.14834] [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: 03/03/2021] [Revised: 03/18/2021] [Accepted: 03/16/2021] [Indexed: 11/24/2022] Open
Abstract
This study investigated the influence of passive tension on Hoffmann reflex during the loading (muscle stretched by passive joint movement) and unloading phase (joint returned to initial position) of muscle stretching. The maximal H‐reflex amplitude (Hmax) was recorded in soleus in 19 young adults during the loading and unloading phases of a passive 30° dorsiflexion, from 90° ankle angle (reference position). Hmax was evoked at similar angles (protocol‐1) or similar passive torque (PT; protocol‐2) during the loading and unloading phases, or during two loading phases separated by a 5‐min stretch hold at 30° ankle dorsiflexion relative to the reference position (protocol‐3). Homosynaptic depression (HD) was assessed with paired H reflexes (0.5‐s interstimulus interval) during the loading and unloading phases (protocol‐4; n=13). In protocol‐1, PT was lesser and Hmax greater during the unloading than the loading phase (p < 0.001). In protocol‐2, no difference in Hmax was observed between phases. In protocol‐3, PT was lesser and Hmax greater during the second than the first loading phase (p < 0.001). Changes in PT during in these three protocols were associated with those in Hmax (r2 ≥ 0.97). In protocol‐4, HD increased and decreased during the loading and unloading phases, respectively (p < 0.001), without differing between phases. Additional experiments (n=12) showed a similar modulation of Hmax in gastrocnemius medialis during loading and unloading phases, while muscle fascicle length did not differ between phases. This study indicates that the H‐reflex modulation during muscle stretching relies in part on mechanisms associated with the PT developed by the muscle‐tendon unit.
Collapse
Affiliation(s)
- Mehdi Datoussaid
- Laboratory of Applied Biology & Research Unit in Applied Neurophysiology (LABNeuro), ULB-Neurosciences Institute (UNI), Université Libre de Bruxelles (ULB), Brussels, Belgium
| | - Hasnae El Khalouqi
- Laboratory of Applied Biology & Research Unit in Applied Neurophysiology (LABNeuro), ULB-Neurosciences Institute (UNI), Université Libre de Bruxelles (ULB), Brussels, Belgium
| | - Charel Dahm
- Laboratory of Applied Biology & Research Unit in Applied Neurophysiology (LABNeuro), ULB-Neurosciences Institute (UNI), Université Libre de Bruxelles (ULB), Brussels, Belgium
| | - Nathalie Guissard
- Laboratory of Applied Biology & Research Unit in Applied Neurophysiology (LABNeuro), ULB-Neurosciences Institute (UNI), Université Libre de Bruxelles (ULB), Brussels, Belgium
| | - Stéphane Baudry
- Laboratory of Applied Biology & Research Unit in Applied Neurophysiology (LABNeuro), ULB-Neurosciences Institute (UNI), Université Libre de Bruxelles (ULB), Brussels, Belgium
| |
Collapse
|
13
|
Blum KP, Campbell KS, Horslen BC, Nardelli P, Housley SN, Cope TC, Ting LH. Diverse and complex muscle spindle afferent firing properties emerge from multiscale muscle mechanics. eLife 2020; 9:e55177. [PMID: 33370235 PMCID: PMC7769569 DOI: 10.7554/elife.55177] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 12/04/2020] [Indexed: 11/13/2022] Open
Abstract
Despite decades of research, we lack a mechanistic framework capable of predicting how movement-related signals are transformed into the diversity of muscle spindle afferent firing patterns observed experimentally, particularly in naturalistic behaviors. Here, a biophysical model demonstrates that well-known firing characteristics of mammalian muscle spindle Ia afferents - including movement history dependence, and nonlinear scaling with muscle stretch velocity - emerge from first principles of muscle contractile mechanics. Further, mechanical interactions of the muscle spindle with muscle-tendon dynamics reveal how motor commands to the muscle (alpha drive) versus muscle spindle (gamma drive) can cause highly variable and complex activity during active muscle contraction and muscle stretch that defy simple explanation. Depending on the neuromechanical conditions, the muscle spindle model output appears to 'encode' aspects of muscle force, yank, length, stiffness, velocity, and/or acceleration, providing an extendable, multiscale, biophysical framework for understanding and predicting proprioceptive sensory signals in health and disease.
Collapse
Affiliation(s)
- Kyle P Blum
- Department of Physiology, Feinberg School of Medicine, Northwestern UniversityChicagoUnited States
- Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of TechnologyAtlantaUnited States
| | | | - Brian C Horslen
- Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of TechnologyAtlantaUnited States
| | - Paul Nardelli
- School of Biological Sciences, Georgia Institute of TechnologyAtlantaUnited States
| | - Stephen N Housley
- School of Biological Sciences, Georgia Institute of TechnologyAtlantaUnited States
| | - Timothy C Cope
- Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of TechnologyAtlantaUnited States
- School of Biological Sciences, Georgia Institute of TechnologyAtlantaUnited States
| | - Lena H Ting
- Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of TechnologyAtlantaUnited States
- Department of Rehabilitation Medicine, Emory UniversityAtlantaUnited States
| |
Collapse
|
14
|
Willaert J, Desloovere K, Van Campenhout A, Ting LH, De Groote F. Movement History Influences Pendulum Test Kinematics in Children With Spastic Cerebral Palsy. Front Bioeng Biotechnol 2020; 8:920. [PMID: 32850754 PMCID: PMC7426371 DOI: 10.3389/fbioe.2020.00920] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Accepted: 07/16/2020] [Indexed: 11/13/2022] Open
Abstract
The pendulum test assesses quadriceps spasticity by dropping the lower leg of a relaxed patient from the horizontal position and observing limb movement. The first swing excursion (FS) decreases with increasing spasticity severity. Our recent simulation study suggests that the reduced initial swing results from muscle short-range stiffness and its interaction with reflex hyper-excitability. Short-range stiffness emerges from the thixotropic behavior of muscles where fiber stiffness upon stretch increases when the muscle is held isometric. Fiber stiffness might thus be higher during the first swing of the pendulum test than during consecutive swings. In addition, it has recently been suggested that muscle spindle firing reflects fiber force rather than velocity and therefore, reflex activity might depend on fiber stiffness. If this hypothesized mechanism is true, we expect to observe larger first swing excursions and reduced reflex muscle activity when the leg is moved rather than kept isometric before release, especially in patients with increased reflex activity. We performed the pendulum test in 15 children with cerebral palsy (CP) and 15 age-matched typically developing (TD) children in two conditions. In the hold condition, the leg was kept isometric in the extended position before release. In the movement condition, the leg was moved up and down before release to reduce the contribution of short-range stiffness. Knee kinematics and muscle activity were recorded. Moving the leg before release increased first swing excursion (p < 0.001) and this increase was larger in children with CP (21°) than in TD children (8°) (p < 0.005). In addition, pre-movement delayed reflex onset by 87 ms (p < 0.05) and reduced reflex activity as assessed through the area under the curve of rectus femoris electromyography (p < 0.05) in children with CP. The movement history dependence of pendulum kinematics and reflex activity supports our hypothesis that muscle short-range stiffness and its interaction with reflex hyper-excitability contribute to joint hyper-resistance in spastic CP. Our results have implications for standardizing movement history in clinical tests of spasticity and for understanding the role of spasticity in functional movements, where movement history differs from movement history in clinical tests.
Collapse
Affiliation(s)
- Jente Willaert
- Department of Movement Sciences, Katholieke Universiteit Leuven, Leuven, Belgium
| | - Kaat Desloovere
- Department of Rehabilitation Sciences, Katholieke Universiteit Leuven, Leuven, Belgium.,Clinical Motion Analysis Laboratory, Universitair Ziekenhuis Leuven, Leuven, Belgium
| | - Anja Van Campenhout
- Clinical Motion Analysis Laboratory, Universitair Ziekenhuis Leuven, Leuven, Belgium.,Department of Development and Regeneration, Katholieke Universiteit Leuven, Leuven, Belgium.,Department of Orthopedics, Universitair Ziekenhuis Leuven, Leuven, Belgium
| | - Lena H Ting
- Wallace H. Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, Atlanta, GA, United States.,Division of Physical Therapy, Department of Rehabilitation Medicine, Emory University, Atlanta, GA, United States
| | - Friedl De Groote
- Department of Movement Sciences, Katholieke Universiteit Leuven, Leuven, Belgium
| |
Collapse
|
15
|
Hirono T, Ikezoe T, Taniguchi M, Yamagata M, Miyakoshi K, Umehara J, Ichihashi N. Relationship between ankle plantar flexor force steadiness and postural stability on stable and unstable platforms. Eur J Appl Physiol 2020; 120:1075-1082. [DOI: 10.1007/s00421-020-04346-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Accepted: 03/10/2020] [Indexed: 01/06/2023]
|
16
|
Kositsky A, Kidgell DJ, Avela J. Medial Gastrocnemius Muscle Architecture Is Altered After Exhaustive Stretch-Shortening Cycle Exercise. Front Physiol 2020; 10:1511. [PMID: 31920715 PMCID: PMC6933009 DOI: 10.3389/fphys.2019.01511] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2019] [Accepted: 11/29/2019] [Indexed: 11/26/2022] Open
Abstract
Muscle architecture is an important component of muscle function, and recent studies have shown changes in muscle architecture with fatigue. The stretch-shortening cycle is a natural way to study human locomotion, but little is known about how muscle architecture is affected by this type of exercise. This study investigated potential changes in medial gastrocnemius (MG) muscle architecture after exhaustive stretch-shortening cycle exercise. Male athletes (n = 10) performed maximal voluntary contractions (MVC) and maximal drop jump (DJ) tests before and after an exercise task consisting of 100 maximal DJs followed by successive rebound jumping to 70% of the initial maximal height. The exercise task ceased upon failure to jump to 50% of maximal height or volitional fatigue. Muscle architecture of MG was measured using ultrasonography at rest and during MVC, and performance variables were calculated via a force plate and motion analysis. After SSC exercise, MVC (−13.1%; p = 0.005; dz = 1.30), rebound jump height (−14.8%, p = 0.004; dz = 1.32), and ankle joint stiffness (−26.3%; p = 0.008; dz = 1.30) decreased. Ankle joint range of motion (+20.2%; p = 0.011; dz = 1.09) and MG muscle-tendon unit length (+12.0%; p = 0.037; dz = 0.91) during the braking phase of DJ, the immediate drop-off in impact force (termed peak force reduction) (Δ27.3%; p = 0.033; dz = 0.86), and lactate (+9.5 mmol/L; p < 0.001; dz = 3.58) increased. Fascicle length increased at rest (+4.9%; p = 0.013; dz = 1.16) and during MVC (+6.8%; p = 0.048; dz = 0.85). Pennation angle decreased at rest (−6.5%; p = 0.034, dz = 0.93) and during MVC (−9.8%; p = 0.012; dz = 1.35). No changes in muscle thickness were found at rest (−2.6%; p = 0.066; dz = 0.77) or during MVC (−1.6%; p = 0.204; dz = 0.49). The greater MG muscle-tendon stretch during the DJ braking phase after exercise indicates that muscle damage likely occurred. The lower peak force reduction and ankle joint stiffness, indicative of decreased active stiffness, suggests activation was likely reduced, causing fascicles to shorten less during MVC.
Collapse
Affiliation(s)
- Adam Kositsky
- Biology of Physical Activity, Neuromuscular Research Center, Faculty of Sport and Health Sciences, University of Jyväskylä, Jyväskylä, Finland
| | - Dawson J Kidgell
- Department of Physiotherapy, School of Primary and Allied Health Care, Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, VIC, Australia
| | - Janne Avela
- Biology of Physical Activity, Neuromuscular Research Center, Faculty of Sport and Health Sciences, University of Jyväskylä, Jyväskylä, Finland
| |
Collapse
|
17
|
Škarabot J, Ansdell P, Howatson G, Goodall S, Durbaba R. Corticospinal responses during passive shortening and lengthening of tibialis anterior and soleus in older compared to younger adults. Exp Physiol 2019; 105:419-426. [PMID: 31860743 DOI: 10.1113/ep088204] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Accepted: 12/18/2019] [Indexed: 01/24/2023]
Abstract
NEW FINDINGS What is the central question of this study? Are there age-related differences in corticospinal responses whilst passively changing muscle length? What is the main finding and its importance? In contrast to young, older adults exhibited no modulation of corticospinal excitability in tibialis anterior during passive ankle movement. These data show impaired sensorimotor response in older adults during length changes of tibialis anterior, thus contributing to our understanding of age-related changes in sensorimotor control. ABSTRACT Corticospinal responses have been shown to increase and decrease with passive muscle shortening and lengthening, respectively, as a result of changes in muscle spindle afferent feedback. The ageing sensory system is accompanied by a number of alterations that might influence the processing and integration of sensory information. Consequently, corticospinal excitability might be modulated differently whilst changing muscle length. In 10 older adults (66 ± 4 years), corticospinal responses (MEP/Mmax ) were evoked in a static position, and during passive shortening and lengthening of soleus (SOL) and tibialis anterior (TA), and these data were compared to the re-analysed data pool of 18 younger adults (25 ± 4 years) published previously. Resting motor threshold was greater in SOL compared to TA (P < 0.001), but did not differ between young and older (P = 0.405). No differences were observed in MEP/Mmax between the static position, passive shortening or lengthening in SOL (young: all 0.02 ± 0.01; older: 0.05 ± 0.04, 0.03 ± 0.02 and 0.04 ± 0.01, respectively; P = 0.298), and responses were not dependent on age (P = 0.090). Conversely, corticospinal responses in TA were modulated differently between the age groups (P = 0.002), with greater MEP/Mmax during passive shortening (0.22 ± 0.12) compared to passive lengthening (0.13 ± 0.10) and static position (0.10 ± 0.05) in young (P < 0.001), but unchanged in older adults (0.19 ± 0.11, 0.22 ± 0.11 and 0.18 ± 0.07, respectively; P ≥ 0.867). The present experiment shows that length-dependent changes in corticospinal excitability in TA of the young are not evident in older adults. This suggests impaired sensorimotor response during muscle length changes in older age that might only be present in ankle flexors, but not extensors.
Collapse
Affiliation(s)
- Jakob Škarabot
- Faculty of Health & Life Sciences, Northumbria University, Newcastle upon Tyne, UK
| | - Paul Ansdell
- Faculty of Health & Life Sciences, Northumbria University, Newcastle upon Tyne, UK
| | - Glyn Howatson
- Faculty of Health & Life Sciences, Northumbria University, Newcastle upon Tyne, UK.,Water Research Group, School of Environmental Sciences and Development, Northwest University, Potchefstroom, South Africa
| | - Stuart Goodall
- Faculty of Health & Life Sciences, Northumbria University, Newcastle upon Tyne, UK
| | - Rade Durbaba
- Faculty of Health & Life Sciences, Northumbria University, Newcastle upon Tyne, UK
| |
Collapse
|
18
|
Škarabot J, Ansdell P, Brownstein CG, Hicks KM, Howatson G, Goodall S, Durbaba R. Corticospinal excitability of tibialis anterior and soleus differs during passive ankle movement. Exp Brain Res 2019; 237:2239-2254. [PMID: 31243484 PMCID: PMC6675771 DOI: 10.1007/s00221-019-05590-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 06/20/2019] [Indexed: 12/22/2022]
Abstract
The purpose of this study was to assess corticospinal excitability of soleus (SOL) and tibialis anterior (TA) at a segmental level during passive ankle movement. Four experimental components were performed to assess the effects of passive ankle movement and muscle length on corticospinal excitability (MEP/Mmax) at different muscle lengths, subcortical excitability at the level of lumbar spinal segments (LEP/Mmax), intracortical inhibition (SICI) and facilitation (ICF), and H-reflex in SOL and TA. In addition, the degree of fascicle length changes between SOL and TA was assessed in a subpopulation during passive ankle movement. Fascicles shortened and lengthened with joint movement during passive shortening and lengthening of SOL and TA to a similar degree (p < 0.001). Resting motor threshold was greater in SOL compared to TA (p ≤ 0.014). MEP/Mmax was facilitated in TA during passive shortening relative to the static position (p ≤ 0.023) and passive lengthening (p ≤ 0.001), but remained similar during passive ankle movement in SOL (p ≥ 0.497), regardless of muscle length at the point of stimulus (p = 0.922). LEP/Mmax (SOL: p = 0.075, TA: p = 0.071), SICI (SOL: p = 0.427, TA: p = 0.540), and ICF (SOL: p = 0.177, TA: p = 0.777) remained similar during passive ankle movement. H-reflex was not different across conditions in TA (p = 0.258), but was reduced during passive lengthening compared to shortening in SOL (p = 0.048). These results suggest a differential modulation of corticospinal excitability between plantar and dorsiflexors during passive movement. The corticospinal behaviour observed might be mediated by an increase in corticospinal drive as a result of reduced afferent input during muscle shortening and appears to be flexor-biased.
Collapse
Affiliation(s)
- Jakob Škarabot
- Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, England, NE1 8ST, UK
| | - Paul Ansdell
- Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, England, NE1 8ST, UK
| | - Callum G Brownstein
- Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, England, NE1 8ST, UK.,Univ Lyon, UJM-Saint-Etienne, Laboratoire Interuniversitaire de Biologie de la Motricité, EA 7424, 42023, Saint-Étienne, France
| | - Kirsty M Hicks
- Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, England, NE1 8ST, UK
| | - Glyn Howatson
- Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, England, NE1 8ST, UK.,Water Research Group, School of Environmental Sciences and Development, Northwest University, Potchefstroom, South Africa
| | - Stuart Goodall
- Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, England, NE1 8ST, UK
| | - Rade Durbaba
- Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, England, NE1 8ST, UK.
| |
Collapse
|
19
|
Henry M, Baudry S. Age-related changes in leg proprioception: implications for postural control. J Neurophysiol 2019; 122:525-538. [PMID: 31166819 DOI: 10.1152/jn.00067.2019] [Citation(s) in RCA: 113] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
In addition to being a prerequisite for many activities of daily living, the ability to maintain steady upright standing is a relevant model to study sensorimotor integrative function. Upright standing requires managing multimodal sensory inputs to produce finely tuned motor output that can be adjusted to accommodate changes in standing conditions and environment. The sensory information used for postural control mainly arises from the vestibular system of the inner ear, vision, and proprioception. Proprioception (sense of body position and movement) encompasses signals from mechanoreceptors (proprioceptors) located in muscles, tendons, and joint capsules. There is general agreement that proprioception signals from leg muscles provide the primary source of information for postural control. This is because of their exquisite sensitivity to detect body sway during unperturbed upright standing that mainly results from variations in leg muscle length induced by rotations around the ankle joint. However, aging is associated with alterations of muscle spindles and their neural pathways, which induce a decrease in the sensitivity, acuity, and integration of the proprioceptive signal. These alterations promote changes in postural control that reduce its efficiency and thereby may have deleterious consequences for the functional independence of an individual. This narrative review provides an overview of how aging alters the proprioceptive signal from the legs and presents compelling evidence that these changes modify the neural control of upright standing.
Collapse
Affiliation(s)
- Mélanie Henry
- Laboratory of Applied Biology and Research Unit in Applied Neurophysiology, ULB Neuroscience Institute, Université libre de Bruxelles, Brussels, Belgium
| | - Stéphane Baudry
- Laboratory of Applied Biology and Research Unit in Applied Neurophysiology, ULB Neuroscience Institute, Université libre de Bruxelles, Brussels, Belgium
| |
Collapse
|
20
|
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.
Collapse
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
| |
Collapse
|
21
|
Raiteri BJ, Hahn D. A reduction in compliance or activation level reduces residual force depression in human tibialis anterior. Acta Physiol (Oxf) 2019; 225:e13198. [PMID: 30300958 DOI: 10.1111/apha.13198] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 10/02/2018] [Accepted: 10/04/2018] [Indexed: 12/31/2022]
Abstract
AIM We investigated if residual force depression (rFD) is present during voluntary fixed-end contractions of human tibialis anterior (TA) and whether reducing TA's activation level after active shortening could reduce rFD. METHODS Ten participants performed fixed-end dorsiflexion contractions to a low, moderate or high level while electromyography (EMG), dorsiflexion force and TA ultrasound images were recorded. Contractions were force- or EMG-matched and after the low or high contraction level was attained, participants respectively increased or decreased their force/EMG to a moderate level. Participants also performed moderate level contractions while the TA muscle-tendon unit (MTU) was lengthened during the force/EMG rise to the reference MTU length. RESULTS Equivalent fascicle shortening over moderate and low to moderate level contractions did not alter EMG (P = 0.45) or dorsiflexion force (P = 0.47) at the moderate level. Greater initial fascicle shortening magnitudes (1.7 mm; P ≤ 0.01) to the high contraction level did not alter EMG (P = 0.45) or dorsiflexion force (P = 0.30) at the subsequent moderate level compared with moderate level contractions. TA MTU lengthening during the initial force/EMG rise reduced TA fascicle shortening (-2.5 mm; P ≤ 0.01), which reduced EMG (-3.9% MVC; P < 0.01) and increased dorsiflexion force (3.7% MVC; P < 0.01) at the moderate level compared with fixed-end moderate level contractions. CONCLUSION rFD is present during fixed-end dorsiflexion contractions because fascicles actively shorten as force/EMG increases and rFD can be reduced by reducing the effective MTU compliance. A reduction in muscle activation level also reduces rFD by potentially triggering residual force enhancement-related mechanisms as force drops and some fascicles actively lengthen.
Collapse
Affiliation(s)
- Brent J. Raiteri
- Human Movement Science, Faculty of Sport Science Ruhr University Bochum Bochum Germany
| | - Daniel Hahn
- Human Movement Science, Faculty of Sport Science Ruhr University Bochum Bochum Germany
- School of Human Movement and Nutrition Sciences The University of Queensland Brisbane QueenslandAustralia
| |
Collapse
|
22
|
Knellwolf TP, Burton AR, Hammam E, Macefield VG. Firing properties of muscle spindles supplying the intrinsic foot muscles of humans in unloaded and freestanding conditions. J Neurophysiol 2018; 121:74-84. [PMID: 30427762 DOI: 10.1152/jn.00539.2018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
We recently developed an approach for recording from muscle spindles in the intrinsic muscles of the foot in freestanding humans by inserting a tungsten microelectrode into the posterior tibial nerve behind the medial malleolus of the ankle. Here we characterize the behavior of muscle spindles in the small muscles of the foot in 1) seated subjects with the leg horizontal and the foot naturally plantarflexed and 2) standing subjects. In the first study, recordings were made from 26 muscle spindle afferents located within flexor digiti minimi brevis ( n = 4), abductor digiti minimi ( n = 3), quadratus plantae ( n = 3), plantar interossei ( n = 4), flexor digitorum brevis ( n = 3), dorsal interossei ( n = 2), and lumbricals ( n = 2), with one each supplying abductor hallucis, adductor hallucis, and flexor hallucis brevis. The identity of another two muscle afferents was unknown. The majority of the units were silent at rest, only seven (27%) being spontaneously active. Because of the anatomic constraints of the foot, some spindles supplying muscles acting on the toes responded to movements of one or more digits. In the second study, 12 muscle spindle afferents were examined during standing. The ongoing discharge of eight spindle afferents covaried with changes in the center of pressure during postural sway. We conclude that the majority of spindle endings in the small muscles of the foot are silent at rest, which may allow them to encode changes in conformation of the foot when it is loaded during standing. Moreover, these muscle spindle afferents can provide useful proprioceptive information during standing and postural sway. NEW & NOTEWORTHY We have characterized the firing properties of muscle spindles in the intrinsic muscles of the human foot for the first time. The majority of the spindle endings are silent in seated subjects, and most fire tonically during standing, their discharge covarying with center of pressure during postural sway. We conclude that spindle endings in the intrinsic muscles of the foot provide useful proprioceptive information during free standing.
Collapse
Affiliation(s)
- T P Knellwolf
- School of Medicine, Western Sydney University , Sydney , Australia
| | - A R Burton
- School of Medicine, Western Sydney University , Sydney , Australia.,Neuroscience Research Institute , Sydney , Australia
| | - E Hammam
- School of Medicine, Western Sydney University , Sydney , Australia
| | - V G Macefield
- School of Medicine, Western Sydney University , Sydney , Australia.,Neuroscience Research Institute , Sydney , Australia.,Baker Heart and Diabetes Institute , Melbourne , Australia
| |
Collapse
|
23
|
Interaction between muscle tone, short-range stiffness and increased sensory feedback gains explains key kinematic features of the pendulum test in spastic cerebral palsy: A simulation study. PLoS One 2018; 13:e0205763. [PMID: 30335860 PMCID: PMC6193683 DOI: 10.1371/journal.pone.0205763] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 10/01/2018] [Indexed: 11/19/2022] Open
Abstract
The pendulum test is a sensitive clinical assessment of spasticity where the lower leg is dropped from the horizontal position and features of limb motion are recorded. Three key kinematic features are associated with the degree of severity of spasticity in children with cerebral palsy: decreased initial limb excursion, reduced number of limb oscillations, and a non-vertical resting limb angle. While spasticity is attributed to increased velocity-dependent resistance to motion, prior models simulating increased sensorimotor feedback of muscle velocity fail to explain the key pendulum test kinematic outcomes in spastic individuals. Here we hypothesized that increased muscle tone, causing a transient increase in muscle force, i.e. short-range stiffness, could account for reduced first swing excursion and non-vertical resting limb angle. We further hypothesized that hyperreflexia modeled based on muscle fiber force, and not velocity, feedback would be necessary to reduce the number of oscillations because of its interaction with transiently increased muscle force due to short-range stiffness. We simulated the lower leg as a torque-driven single-link pendulum. Muscle tone was modeled as a constant baseline joint torque, short-range stiffness torque was dependent on the level of muscle tone, and delayed sensory feedback torque to simulate reflex activity was based on either muscle velocity or force. Muscle tone and transient short-range stiffness were necessary to simulate decreased initial swing excursion and non-vertical resting leg angle. Moreover, the reduction in the number of oscillations was best reproduced by simulating stretch reflex activity in terms of force, and not velocity, feedback. Varying only baseline muscle torque and reflex gain, we simulated a range of pendulum test kinematics observed across different levels of spasticity. Our model lends insight into physiological mechanisms of spasticity whose contributions can vary on an individual-specific basis, and potentially across different neurological disorders that manifest spasticity as a symptom.
Collapse
|
24
|
Milton JG, Insperger T, Cook W, Harris DM, Stepan G. Microchaos in human postural balance: Sensory dead zones and sampled time-delayed feedback. Phys Rev E 2018; 98:022223. [PMID: 30253531 DOI: 10.1103/physreve.98.022223] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Indexed: 06/08/2023]
Abstract
Models for the stabilization of an inverted pendulum figure prominently in studies of human balance control. Surprisingly, fluctuations in measures related to the vertical displacement angle for quietly standing adults with eyes closed exhibit chaos. Here we show that small-amplitude chaotic fluctuations ("microchaos") can be generated by the interplay between three essential components of human neural balance control, namely time-delayed feedback, a sensory dead zone, and frequency-dependent encoding of force. When the sampling frequency of the force encoding is decreased, the sensitivity of the balance control to changes in the initial conditions increases. The sampled, time-delayed nature of the balance control may provide insights into why falls are more common in the very young and the elderly.
Collapse
Affiliation(s)
- John G Milton
- W. M. Keck Science Center, The Claremont Colleges, Claremont, California 91711, USA
| | - Tamas Insperger
- Department of Applied Mechanics, Budapest University of Technology and Economics and MTA-BME Lendület Human Balancing Research Group, 1111 Budapest, Hungary
| | - Walter Cook
- W. M. Keck Science Center, The Claremont Colleges, Claremont, California 91711, USA
| | - David Money Harris
- Department of Engineering, Harvey Mudd College, Claremont, California 91711, USA
| | - Gabor Stepan
- Department of Applied Mechanics, Budapest University of Technology and Economics, 1111 Budapest, Hungary
| |
Collapse
|
25
|
Macefield VG, Knellwolf TP. Functional properties of human muscle spindles. J Neurophysiol 2018; 120:452-467. [DOI: 10.1152/jn.00071.2018] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Muscle spindles are ubiquitous encapsulated mechanoreceptors found in most mammalian muscles. There are two types of endings, primary and secondary, and both are sensitive to changes in muscle length and velocity, with the primary endings having a greater dynamic sensitivity. Unlike other mechanoreceptors in the somatosensory system, muscle spindles are unique in possessing motor innervation, via γ-motoneurons (fusimotor neurons), that control their sensitivity to stretch. Much of what we know about human muscles spindles comes from studying the behavior of their afferents via intraneural microelectrodes (microneurography) inserted into accessible peripheral nerves. We review the functional properties of human muscle spindles, comparing and contrasting with what we know about the functions of muscle spindles studied in experimental animals. As in the cat, many human muscle spindles possess a background discharge that is related to the degree of muscle stretch, but mean firing rates are much lower (~10 Hz). They can faithfully encode changes in muscle fascicle length in passive conditions, but higher level extraction of information is required by the central nervous system to measure changes in muscle length during muscle contraction. Moreover, although there is some evidence supporting independent control of human muscle spindles via fusimotor neurons, any effects are modest compared with the clearly independent control of fusimotor neurons observed in the cat.
Collapse
Affiliation(s)
- Vaughan G. Macefield
- School of Medicine, Western Sydney University, Sydney, Australia
- Neuroscience Research Institute, Sydney, Australia
- Baker Heart & Diabetes Institute, Melbourne, Australia
| | | |
Collapse
|
26
|
Forbes PA, Chen A, Blouin JS. Sensorimotor control of standing balance. HANDBOOK OF CLINICAL NEUROLOGY 2018; 159:61-83. [DOI: 10.1016/b978-0-444-63916-5.00004-5] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/08/2023]
|
27
|
Abstract
The review demonstrates that control of posture and locomotion is provided by systems across the caudal-to-rostral extent of the neuraxis. A common feature of the neuroanatomic organization of the postural and locomotor control systems is the presence of key nodes for convergent input of multisensory feedback in conjunction with efferent copies of the motor command. These nodes include the vestibular and reticular nuclei and interneurons in the intermediate zone of the spinal cord (Rexed's laminae VI-VIII). This organization provides both spatial and temporal coordination of the various goals of the system and ensures that the large repertoire of voluntary movements is appropriately coupled to either anticipatory or reactive postural adjustments that ensure stability and provide the framework to support the intended action. Redundancies in the system allow adaptation and compensation when sensory modalities are impaired. These alterations in behavior are learned through reward- and error-based learning processes implemented through basal ganglia and cerebellar pathways respectively. However, neurodegenerative processes or lesions of these systems can greatly compromise the capacity to sufficiently adapt and sometimes leads to maladaptive changes that impair movement control. When these impairments occur, the risk of falls can be significantly increased and interventions are required to reduce morbidity.
Collapse
Affiliation(s)
- Colum D MacKinnon
- Department of Neurology and Institute for Translational Neuroscience, University of Minnesota, Minneapolis, MN, United States.
| |
Collapse
|
28
|
Blum KP, Lamotte D’Incamps B, Zytnicki D, Ting LH. Force encoding in muscle spindles during stretch of passive muscle. PLoS Comput Biol 2017; 13:e1005767. [PMID: 28945740 PMCID: PMC5634630 DOI: 10.1371/journal.pcbi.1005767] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Revised: 10/10/2017] [Accepted: 09/05/2017] [Indexed: 12/03/2022] Open
Abstract
Muscle spindle proprioceptive receptors play a primary role in encoding the effects of external mechanical perturbations to the body. During externally-imposed stretches of passive, i.e. electrically-quiescent, muscles, the instantaneous firing rates (IFRs) of muscle spindles are associated with characteristics of stretch such as length and velocity. However, even in passive muscle, there are history-dependent transients of muscle spindle firing that are not uniquely related to muscle length and velocity, nor reproduced by current muscle spindle models. These include acceleration-dependent initial bursts, increased dynamic response to stretch velocity if a muscle has been isometric, and rate relaxation, i.e., a decrease in tonic IFR when a muscle is held at a constant length after being stretched. We collected muscle spindle spike trains across a variety of muscle stretch kinematic conditions, including systematic changes in peak length, velocity, and acceleration. We demonstrate that muscle spindle primary afferents in passive muscle fire in direct relationship to muscle force-related variables, rather than length-related variables. Linear combinations of whole muscle-tendon force and the first time derivative of force (dF/dt) predict the entire time course of transient IFRs in muscle spindle Ia afferents during stretch (i.e., lengthening) of passive muscle, including the initial burst, the dynamic response to lengthening, and rate relaxation following lengthening. Similar to acceleration scaling found previously in postural responses to perturbations, initial burst amplitude scaled equally well to initial stretch acceleration or dF/dt, though later transients were only described by dF/dt. The transient increase in dF/dt at the onset of lengthening reflects muscle short-range stiffness due to cross-bridge dynamics. Our work demonstrates a critical role of muscle cross-bridge dynamics in history-dependent muscle spindle IFRs in passive muscle lengthening conditions relevant to the detection and sensorimotor response to mechanical perturbations to the body, and to previously-described history-dependence in perception of limb position.
Collapse
Affiliation(s)
- Kyle P. Blum
- Wallace H. Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, Atlanta, Georgia, United States of America
| | - Boris Lamotte D’Incamps
- Center for Neurophysics, Physiology and Pathophysiology, Université Paris Descartes, Paris, France
| | - Daniel Zytnicki
- Center for Neurophysics, Physiology and Pathophysiology, Université Paris Descartes, Paris, France
| | - Lena H. Ting
- Wallace H. Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, Atlanta, Georgia, United States of America
- Department of Rehabilitation Medicine, Division of Physical Therapy, Emory University, Atlanta, Georgia, United States of America
| |
Collapse
|
29
|
Van Hooren B, Zolotarjova J. The Difference Between Countermovement and Squat Jump Performances: A Review of Underlying Mechanisms With Practical Applications. J Strength Cond Res 2017. [DOI: 10.1519/jsc.0000000000001913] [Citation(s) in RCA: 87] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
30
|
Peters RM, Dalton BH, Blouin JS, Inglis JT. Precise coding of ankle angle and velocity by human calf muscle spindles. Neuroscience 2017; 349:98-105. [PMID: 28263787 DOI: 10.1016/j.neuroscience.2017.02.034] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Revised: 02/15/2017] [Accepted: 02/16/2017] [Indexed: 11/29/2022]
Abstract
Human standing balance control requires the integration of sensory feedback to produce anticipatory, stabilizing ankle torques. However, the ability of human triceps surae muscle spindles to provide reliable sensory feedback regarding the small, slow ankle movements that occur during upright standing has recently come under question. We performed microneurography to directly record axon potentials from single muscle spindle afferents in the human triceps surae during servo-controlled movement of the ankle joint. To simulate movements of the ankle while standing, we delivered random 90-s dorsiflexion/plantar flexion oscillations of the ankle joint, with a peak-to-peak amplitude of 0.7° and frequency content below 0.5Hz. In roughly half of the trials (46%), participants held a low-level, near-isometric contraction of the triceps surae muscles. We demonstrate that afferent activity in a population of muscle spindles closely reflects ankle movements at frequencies and amplitudes characteristic of human standing. Four out of five soleus spindles, and three out of seven gastrocnemius spindles coded for at least a single frequency component of anteroposterior ankle rotation. Concatenating within muscles, coherence was significantly greater for soleus spindles at all stimulus frequencies. Voluntary contraction of the parent muscle reduced spindle sensitivity, but only significantly near the mean power frequency of the stimulus (∼0.3Hz). In conclusion, these results provide direct evidence that triceps surae muscle spindles are potentially capable of providing important sensory feedback for the control of human standing balance.
Collapse
Affiliation(s)
- Ryan M Peters
- School of Kinesiology, University of British Columbia, Vancouver, BC V6T 1Z1, Canada.
| | - Brian H Dalton
- School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, BC V1V 1V7, Canada
| | - Jean-Sébastien Blouin
- School of Kinesiology, University of British Columbia, Vancouver, BC V6T 1Z1, Canada; Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC V6T 1Z3, Canada; Institute for Computing, Information, and Cognitive Systems, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - J Timothy Inglis
- School of Kinesiology, University of British Columbia, Vancouver, BC V6T 1Z1, Canada; Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC V6T 1Z3, Canada; International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, BC V5Z 1M9, Canada
| |
Collapse
|