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Hirofumi T, Douglas R S. Reply to Dr. Mougios. J Appl Physiol (1985) 2024; 136:995. [PMID: 38621252 DOI: 10.1152/japplphysiol.00176.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Accepted: 03/11/2024] [Indexed: 04/17/2024] Open
Affiliation(s)
- Tanaka Hirofumi
- Department of Kinesiology and Health Education, The University of Texas at Austin, Austin, Texas, United States
| | - Seals Douglas R
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, United States
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2
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Nuzzo JL, Nosaka K. Eccentric Muscle Actions Add Complexity to an Already Inconsistent Resistance Exercise Nomenclature. SPORTS MEDICINE - OPEN 2023; 9:118. [PMID: 38112984 PMCID: PMC10730477 DOI: 10.1186/s40798-023-00667-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2023] [Accepted: 12/06/2023] [Indexed: 12/21/2023]
Abstract
An eccentric muscle action (or contraction) is defined as active muscle lengthening against resistance, which occurs when the force generated by the muscle is smaller than the resistance placed upon it. Eccentric resistance exercise, which involves multiple sessions of repeated eccentric muscle actions, improves muscle strength and other health outcomes. In response to this evidence, new exercise technologies have been developed to permit feasible completion of eccentric muscle actions outside of the laboratory. Consequently, participation in eccentric resistance exercise is projected to increase in the future, and communications about eccentric resistance exercise are likely to reach a wide audience, including students in the classroom, athletes in the weightroom, patients who receive telehealth services, and journalists who report on study findings. Previous research has documented inconsistencies in how resistance exercises are named, but the role of eccentric resistance exercises has not been considered. Here, we explain how eccentric resistance exercises add further complexity to an already inconsistent resistance exercise nomenclature. Specifically, action words in exercise names typically describe the movement that occurs in the concentric phase (e.g., "press", "raise", "curl", "pull", "row"). This naming bias likely stems from the fact that traditional resistance exercise equipment, such as free weights and weight stack machines, does not typically accommodate for greater eccentric than concentric strength and thus emphasizes the concentric over eccentric phase. This naming bias is likely to hinder communications about eccentric resistance exercise. Thus, we encourage researchers and practitioners to discuss ways in which resistance exercises can be named more clearly and consistently.
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Affiliation(s)
- James L Nuzzo
- Centre for Human Performance, School of Medical and Health Sciences, Edith Cowan University, 270 Joondalup Drive, Joondalup, WA, 6027, Australia.
| | - Kazunori Nosaka
- Centre for Human Performance, School of Medical and Health Sciences, Edith Cowan University, 270 Joondalup Drive, Joondalup, WA, 6027, Australia
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3
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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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4
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Encarnación-Martínez A, García-Gallart A, Pérez-Soriano P, Catalá-Vilaplana I, Rizo-Albero J, Sanchis-Sanchis R. Effect of Hamstring Tightness and Fatigue on Dynamic Stability and Agility in Physically Active Young Men. SENSORS (BASEL, SWITZERLAND) 2023; 23:1633. [PMID: 36772673 PMCID: PMC9921967 DOI: 10.3390/s23031633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 01/31/2023] [Accepted: 02/01/2023] [Indexed: 06/18/2023]
Abstract
Hamstring extensibility has been defined as a factor to diminished dynamic stability and therefore increased risk of injury. The purpose of this study was to analyse the effects of hamstring tightness and fatigue on dynamic stability and agility. Nineteen participants were divided between the normal extensibility group (NEG) (n = 9, 82.2° ± 12.4°) and hamstrings tightness group (HTG) (n = 10, 64° ± 4.9°) using the passive straight leg raise test. To analyse dynamic stability and agility, they performed the modified Star Excursion Balance Test (mSEBT) and Dynamic Postural Stability Index (DPSI), and hexagon agility test, respectively, before and after a fatigue protocol. A two-way repeated measures ANOVA was used to determine differences among conditions: NEG vs. HTG, and rested vs. fatigued. HTG showed a significantly lower reach in the anterior direction in the mSEBT in pre- and post-fatigue than NEG. Participants in the NEG showed poor stability after landing in the mediolateral direction on DPSI post-fatigue. No significant changes were found in agility related with the group nor fatigue state. Participants with hamstring extensibility reduction has no differences in dynamic stability after landing nor agility after fatigue test, but significantly affects reaching distances during one-leg balance. As a conclusion, a reduction in range of motion in HTG was observed, but no other effects were observed on performance and dynamic stability after a local fatigue protocol depending on hamstring extensibility.
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Affiliation(s)
- Alberto Encarnación-Martínez
- Research Group in Sports Biomechanics (GIBD), Department of Physical Education and Sports, University of Valencia, 46010 Valencia, Spain
| | - Antonio García-Gallart
- The Civil Guard, Secretary of State for Security, Ministry of the Interior, 28010 Madrid, Spain
| | - Pedro Pérez-Soriano
- Research Group in Sports Biomechanics (GIBD), Department of Physical Education and Sports, University of Valencia, 46010 Valencia, Spain
| | - Ignacio Catalá-Vilaplana
- Research Group in Sports Biomechanics (GIBD), Department of Physical Education and Sports, University of Valencia, 46010 Valencia, Spain
| | - Julia Rizo-Albero
- Research Group in Sports Biomechanics (GIBD), Department of Physical Education and Sports, University of Valencia, 46010 Valencia, Spain
| | - Roberto Sanchis-Sanchis
- Research Group in Sports Biomechanics (GIBD), Department of Physical Education and Sports, University of Valencia, 46010 Valencia, Spain
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5
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Brooks SV, Guzman SD, Ruiz LP. Skeletal muscle structure, physiology, and function. HANDBOOK OF CLINICAL NEUROLOGY 2023; 195:3-16. [PMID: 37562874 DOI: 10.1016/b978-0-323-98818-6.00013-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/12/2023]
Abstract
Contractions of skeletal muscles provide the stability and power for all body movements. Consequently, any impairment in skeletal muscle function results in some degree of instability or immobility. Factors that influence skeletal muscle structure and function are therefore of great interest scientifically and clinically. Injury, neuromuscular disease, and old age are among the factors that commonly contribute to impairments in skeletal muscle function. The goal of this chapter is to summarize the fundamentals of skeletal muscle structure and function to provide foundational knowledge for this Handbook volume. We examine the molecular interactions that provide the basis for the generation of force and movement, discuss mechanisms of the regulation of contraction at the level of myofibers, and introduce concepts of the activation and control of muscle function in vivo. Where appropriate, the chapter updates the emerging science that will increase understanding of muscle function.
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Affiliation(s)
- Susan V Brooks
- Department of Molecular & Integrative Physiology, University of Michigan, Ann Arbor, MI, United States; Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States.
| | - Steve D Guzman
- Department of Molecular & Integrative Physiology, University of Michigan, Ann Arbor, MI, United States
| | - Lloyd P Ruiz
- Department of Molecular & Integrative Physiology, University of Michigan, Ann Arbor, MI, United States
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6
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Ozone K, Kokubun T, Takahata K, Takahashi H, Yoneno M, Oka Y, Minegishi Y, Arakawa K, Kano T, Murata K, Kanemura N. Structural and pathological changes in the enthesis are influenced by the muscle contraction type during exercise. J Orthop Res 2022; 40:2076-2088. [PMID: 34862672 DOI: 10.1002/jor.25233] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 08/10/2021] [Accepted: 11/20/2021] [Indexed: 02/04/2023]
Abstract
Mechanical stress is involved in the onset of sports-related enthesopathy. Although the amount of exercise undertaken is a recognized problem during disease onset, changes in muscle contraction type are also involved in the increase in mechanical stress during exercise. This study aimed to clarify the effects of increased mechanical stress associated with muscle contraction type and amount of exercise on enthesis. Twenty mice underwent treadmill exercise, and the muscle contraction type and overall load during exercise were adjusted by varying the angle and speed conditions. Histological analysis was used to the cross-sectional area of the muscle; area of the enthesis fibrocartilage (FC), and expression of inflammation-, degeneration-, and calcification-related factors in the FC area. In addition, the volume and structure of the bone and FC area were examined using microcomputer imaging. Molecular biological analysis was conducted to compare relative expression levels of inflammation and cytokine-related factors in tendons. The Overuse group, which increased the amount of exercise, showed no significant differences in parameters compared to the sedentary mice (Control group). The mice subjected to slow-speed downhill running (Misuse group) showed pathological changes compared to the Control and Overuse groups, despite the small amount of exercise. Thus, the enthesis FC area may be altered by local mechanical stress that would be increased by eccentric muscle contraction rather than by mechanical stress that increases with the overall amount of exercise. Clinical Significance: The muscle contraction type might be more involved in the onset of sports-related enthesopathy rather than the amount of exercise.
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Affiliation(s)
- Kaichi Ozone
- Department of Health and Social Services, Health and Social Services, Graduate School of Saitama Prefectural University, Koshigaya, Saitama, Japan.,Japan Society for the Promotion of Science, Tokyo, Japan
| | - Takanori Kokubun
- Department of Physical Therapy, Health and Social Services, Saitama Prefectural University, Koshigaya, Saitama, Japan
| | - Kei Takahata
- Department of Health and Social Services, Health and Social Services, Graduate School of Saitama Prefectural University, Koshigaya, Saitama, Japan
| | - Haruna Takahashi
- Department of Health and Social Services, Health and Social Services, Graduate School of Saitama Prefectural University, Koshigaya, Saitama, Japan
| | - Moe Yoneno
- Department of Health and Social Services, Health and Social Services, Graduate School of Saitama Prefectural University, Koshigaya, Saitama, Japan
| | - Yuichiro Oka
- Department of Health and Social Services, Health and Social Services, Graduate School of Saitama Prefectural University, Koshigaya, Saitama, Japan
| | - Yuki Minegishi
- Department of Health and Social Services, Health and Social Services, Graduate School of Saitama Prefectural University, Koshigaya, Saitama, Japan.,Japan Society for the Promotion of Science, Tokyo, Japan
| | - Kohei Arakawa
- Department of Health and Social Services, Health and Social Services, Graduate School of Saitama Prefectural University, Koshigaya, Saitama, Japan
| | - Takuma Kano
- Department of Health and Social Services, Health and Social Services, Graduate School of Saitama Prefectural University, Koshigaya, Saitama, Japan
| | - Kenji Murata
- Department of Physical Therapy, Health and Social Services, Saitama Prefectural University, Koshigaya, Saitama, Japan
| | - Naohiko Kanemura
- Department of Physical Therapy, Health and Social Services, Saitama Prefectural University, Koshigaya, Saitama, Japan
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7
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Fidan M, Bayrak A, Karli U. A novel adaptable isometric strength analysis and exercise development system design. Proc Inst Mech Eng H 2021; 235:913-926. [PMID: 33971770 DOI: 10.1177/09544119211015562] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In this study, a low-cost and adaptable isometric strength measurement and exercise development system are described. The implemented system consists of mechanical structure, force measurement sensor, electronic circuit, and computer software. Isometric-isotonic (via spring resistance) strength analysis and various exercise programs can be applied with the system. The developed system has a lower cost compared to its counterparts in the literature and has a structure that can be adapted to different machines and measuring methods. The operability and reliability of the isometric strength measurement and exercise development system have been proven by calibration tests.
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Affiliation(s)
- Murat Fidan
- Department of Electrical and Electronic Engineering, Faculty of Engineering, Bolu Abant Izzet Baysal University, Bolu, Turkey
| | - Alper Bayrak
- Department of Electrical and Electronic Engineering, Faculty of Engineering, Bolu Abant Izzet Baysal University, Bolu, Turkey
| | - Umid Karli
- Department of Coaching Education, Faculty of Sports Sciences, Bolu Abant Izzet Baysal University, Bolu, Turkey
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8
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Assessing the Validity and Reliability of A Low-Cost Microcontroller-Based Load Cell Amplifier for Measuring Lower Limb and Upper Limb Muscular Force. SENSORS 2020; 20:s20174999. [PMID: 32899264 PMCID: PMC7506672 DOI: 10.3390/s20174999] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 08/28/2020] [Accepted: 08/31/2020] [Indexed: 11/16/2022]
Abstract
Lower and upper limb maximum muscular force development is an important indicator of physical capacity. Manual muscle testing, load cell coupled with a signal conditioner, and handheld dynamometry are three widely used techniques for measuring isometric muscle strength. Recently, there is a proliferation of low-cost tools that have potential to be used to measure muscle strength. This study examined both the criterion validity, inter-day reliability and intra-day reliability of a microcontroller-based load cell amplifier for quantifying muscle strength. To do so, a low-cost microcontroller-based load cell amplifier for measuring lower and upper limb maximal voluntary isometric muscular force was compared to a commercial grade signal conditioner and to a handheld dynamometer. The results showed that the microcontroller-based load cell amplifier correlated nearly perfectly (Pearson's R-values between 0.947 to 0.992) with the commercial signal conditioner and the handheld dynamometer, and showed good to excellent association when calculating ICC scores, with values of 0.9582 [95% C.I.: 0.9297-0.9752] for inter-day reliability and of 0.9269 [95% C.I.: 0.8909-0.9533] for session one, intra-day reliability. Such results may have implications for how the evaluation of muscle strength measurement is conducted in the future, particularly for offering a commercial-like grade quality, low cost, portable and flexible option.
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9
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Shoulder muscle activation strategies differ when lifting or lowering a load. Eur J Appl Physiol 2020; 120:2417-2429. [PMID: 32803382 DOI: 10.1007/s00421-020-04464-9] [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: 02/25/2020] [Accepted: 08/04/2020] [Indexed: 12/30/2022]
Abstract
PURPOSE Lowering a load could be associated with abnormal shoulder and scapular motion. We tested the hypothesis that lowering a load involves different shoulder muscle coordination strategies compared to lifting a load. METHODS EMG activity of 13 muscles was recorded in 30 healthy volunteers who lifted and lowered a 6, 12 or 18 kg box between three shelves. Kinematics, EMG levels and muscle synergies, extracted using non-negative matrix factorization, were analyzed. RESULTS We found greater muscle activity level during lowering in four muscles (+ 1-2% MVC in anterior deltoid, biceps brachii, serratus anterior and pectoralis major). The movements were performed faster during lifting (18.2 vs. 15.9 cm/s) but with similar hand paths and segment kinematics. The number of synergies was the same in both tasks. Two synergies were identified in ~ 75% of subjects, and one synergy in the others. Synergy #1 mainly activated prime movers' muscles, while synergy #2 co-activated several antagonist muscles. Synergies' structure was similar between lifting and lowering (Pearson's r ≈ 0.9 for synergy #1 and 0.7-08 for synergy #2). Synergy #2 was more activated during lowering and explained the greater activity observed in anterior deltoid, serratus anterior and pectoralis. CONCLUSION Lifting and lowering a load were associated with similar synergy structure. In 3/4 of subjects, lowering movements involved greater activation of a "multiple antagonists" synergy. The other subjects co-contracted all shoulder muscles as a unit in both conditions. These inter-individual differences should be investigated in the occurrence of shoulder musculoskeletal disorders.
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10
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Stožer A, Vodopivc P, Križančić Bombek L. Pathophysiology of exercise-induced muscle damage and its structural, functional, metabolic, and clinical consequences. Physiol Res 2020; 69:565-598. [PMID: 32672048 DOI: 10.33549/physiolres.934371] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Extreme or unaccustomed eccentric exercise can cause exercise-induced muscle damage, characterized by structural changes involving sarcomere, cytoskeletal, and membrane damage, with an increased permeability of sarcolemma for proteins. From a functional point of view, disrupted force transmission, altered calcium homeostasis, disruption of excitation-contraction coupling, as well as metabolic changes bring about loss of strength. Importantly, the trauma also invokes an inflammatory response and clinically presents itself by swelling, decreased range of motion, increased passive tension, soreness, and a transient decrease in insulin sensitivity. While being damaging and influencing heavily the ability to perform repeated bouts of exercise, changes produced by exercise-induced muscle damage seem to play a crucial role in myofibrillar adaptation. Additionally, eccentric exercise yields greater hypertrophy than isometric or concentric contractions and requires less in terms of metabolic energy and cardiovascular stress, making it especially suitable for the elderly and people with chronic diseases. This review focuses on our current knowledge of the mechanisms underlying exercise-induced muscle damage, their dependence on genetic background, as well as their consequences at the structural, functional, metabolic, and clinical level. A comprehensive understanding of these is a prerequisite for proper inclusion of eccentric training in health promotion, rehabilitation, and performance enhancement.
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Affiliation(s)
- A Stožer
- Institute of Physiology, Faculty of Medicine, University of Maribor, Slovenia.
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11
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Sumi K, Ashida K, Nakazato K. Repeated stretch-shortening contraction of the triceps surae attenuates muscle atrophy and liver dysfunction in a rat model of inflammation. Exp Physiol 2020; 105:1111-1123. [PMID: 32394614 DOI: 10.1113/ep088622] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Accepted: 05/05/2020] [Indexed: 12/15/2022]
Abstract
NEW FINDINGS What is the central question of this study? Is stretch-shortening contraction effective to attenuate skeletal muscle atrophy and hepatic dysfunction in a rat model of peptidoglycan-polysaccharide (PG-PS)-induced inflammation (PG-PS rat)? What are the main findings and their importance? Stretch-shortening contraction attenuates skeletal muscle atrophy in the trained leg and increases circulating interleukin-10 in PG-PS rats. Stretch-shortening contraction also ameliorates liver dysfunction in PG-PS rats, possibly via increased blood interleukin-10. These findings are important because they suggest that stretch-shortening contraction is effective to maintain liver function in addition to exercised skeletal muscle mass. ABSTRACT Stretch-shortening contraction (SSC) is an effective modality to improve skeletal muscle mass. However, the beneficial effects of SSC in the presence of chronic inflammation remain unclear. Here, we imposed five SSC sessions unilaterally on the triceps surae in young female Lewis rats. Rats were injected with vehicle or peptidoglycan-polysaccharide (PG-PS) to induce long-lasting inflammation. The PG-PS reduced gastrocnemius muscle mass in both legs, but that of the SSC-trained leg was significantly greater than that of the contralateral leg. Circulating pro-inflammatory cytokines, such as IL-1β, were significantly increased by PG-PS injection, even if carrying out SSC. The circulating anti-inflammatory cytokine IL-10 increased with SSC in both healthy and inflammatory conditions. Stretch-shortening contraction also prevented increases in serum aspartate aminotransferase activity and plasma free phenylalanine concentration induced by PG-PS, in comparison to the control resistance exercise consisting of isometric contractions. Moreover, aspartate aminotransferase and phenylalanine concentrations demonstrated a significant and negative correlation with IL-10/IL-1β values (r = -0.61, P = 0.017, and r = -0.66, P = 0.008, respectively). These results suggest that SSC training is effective to reduce both muscle atrophy and the hepatic dysfunction induced by PG-PS, mediated, at least in part, through an increase in circulating IL-10.
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Affiliation(s)
- Koichiro Sumi
- Food Microbiology and Function Research Laboratories, R&D Division, Meiji Co., Ltd, Hachiouji, Tokyo, Japan
| | - Kinya Ashida
- Food Microbiology and Function Research Laboratories, R&D Division, Meiji Co., Ltd, Hachiouji, Tokyo, Japan
| | - Koichi Nakazato
- Department of Exercise Physiology, Nippon Sports Science University, Setagaya-ku, Tokyo, Japan
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12
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Greene CS, Menchel HF. The Use of Oral Appliances in the Management of Temporomandibular Disorders. Oral Maxillofac Surg Clin North Am 2018; 30:265-277. [DOI: 10.1016/j.coms.2018.04.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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13
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Rating of Perceived Exertion During Concentric and Eccentric Cycling: Are We Measuring Effort or Exertion? Int J Sports Physiol Perform 2018; 13:517-523. [PMID: 29035598 DOI: 10.1123/ijspp.2017-0171] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Despite the terms' often being used interchangeably, it has been suggested that perceptions of effort and perceptions of exertion may differ. Eccentric (ECC) cycling may provide a model of exercise by which differences between these perceptions can be examined. PURPOSE To examine and compare perceptions of effort and exertion during ECC and concentric (CONC) cycling at 4 intensities. METHODS Ten healthy male participants (mean [SD]: age = 29.8 [2.3] y) performed an incremental cycling test for the determination of maximal aerobic power output, followed in a randomized and crossover design, by four 5-min bouts (30%, 60%, 80%, and maximal) of either ECC or CONC cycling. Through each bout, participants were asked to report their perceived effort, exertion, and muscle pain. Heart rate and oxygen consumption were continuously recorded throughout each bout. RESULTS Perceived exertion was greater for CONC at 30% (8.5 [1.5] vs 7.1 [1.8]; P = .01), 60% (12.4 [1.4] vs 10.3 [2.0]; P = .01), 80% (15.8 [1.7] vs 12.4 [2.5]; P < .01), and maximal (17.2 [1.3] vs 15.6 [1.8]; P = .03) in comparison with ECC. Perceptions of effort and pain were similar between CONC and ECC. Heart rate and oxygen consumption were greater during CONC than ECC. CONCLUSIONS Perceived exertion was greater during CONC compared with ECC cycling, yet effort was similar between conditions despite different physiological stress. Such findings have implications for understanding the development of such perceptions during exercise.
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14
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Toigo M, Flück M, Riener R, Klamroth-Marganska V. Robot-assisted assessment of muscle strength. J Neuroeng Rehabil 2017; 14:103. [PMID: 29020968 PMCID: PMC5637351 DOI: 10.1186/s12984-017-0314-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Accepted: 10/03/2017] [Indexed: 11/14/2022] Open
Abstract
Impairment of neuromuscular function in neurological disorders leads to reductions in muscle force, which may lower quality of life. Rehabilitation robots that are equipped with sensors are able to quantify the extent of muscle force impairment and to monitor a patient during the process of neurorehabilitation with sensitive and objective assessment methods. In this article, we provide an overview of fundamental aspects of muscle function and how the corresponding variables can be quantified by means of meaningful robotic assessments that are primarily oriented towards upper limb neurorehabilitation. We discuss new concepts for the assessment of muscle function, and present an overview of the currently available systems for upper limb measurements. These considerations culminate in practical recommendations and caveats for the rational quantification of force magnitude, force direction, moment of a force, impulse, critical force (neuromuscular fatigue threshold) and state and trait levels of fatigue.
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Affiliation(s)
- Marco Toigo
- Laboratory for Muscle Plasticity, Balgrist University Hospital, University of Zurich, Zurich, Switzerland.
| | - Martin Flück
- Laboratory for Muscle Plasticity, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
| | - Robert Riener
- Sensory-Motor Systems Lab, Department of Health Sciences and Technology ETH Zurich, Zurich, Switzerland.,Balgrist University Hospital, University of Zurich, Zurich, Switzerland
| | - Verena Klamroth-Marganska
- Sensory-Motor Systems Lab, Department of Health Sciences and Technology ETH Zurich, Zurich, Switzerland. .,Balgrist University Hospital, University of Zurich, Zurich, Switzerland.
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15
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Herzog W, Schappacher G, DuVall M, Leonard TR, Herzog JA. Residual Force Enhancement Following Eccentric Contractions: A New Mechanism Involving Titin. Physiology (Bethesda) 2017; 31:300-12. [PMID: 27252165 DOI: 10.1152/physiol.00049.2014] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Eccentric muscle properties are not well characterized by the current paradigm of the molecular mechanism of contraction: the cross-bridge theory. Findings of force contributions by passive structural elements a decade ago paved the way for a new theory. Here, we present experimental evidence and theoretical support for the idea that the structural protein titin contributes to active force production, thereby explaining many of the unresolved properties of eccentric muscle contraction.
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Affiliation(s)
- W Herzog
- University of Calgary Human Performance Laboratory, Calgary, Alberta, Canada
| | - G Schappacher
- University of Calgary Human Performance Laboratory, Calgary, Alberta, Canada
| | - M DuVall
- University of Calgary Human Performance Laboratory, Calgary, Alberta, Canada
| | - T R Leonard
- University of Calgary Human Performance Laboratory, Calgary, Alberta, Canada
| | - J A Herzog
- University of Calgary Human Performance Laboratory, Calgary, Alberta, Canada
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Hessel AL, Lindstedt SL, Nishikawa KC. Physiological Mechanisms of Eccentric Contraction and Its Applications: A Role for the Giant Titin Protein. Front Physiol 2017; 8:70. [PMID: 28232805 PMCID: PMC5299520 DOI: 10.3389/fphys.2017.00070] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Accepted: 01/25/2017] [Indexed: 12/11/2022] Open
Abstract
When active muscles are stretched, our understanding of muscle function is stretched as well. Our understanding of the molecular mechanisms of concentric contraction has advanced considerably since the advent of the sliding filament theory, whereas mechanisms for increased force production during eccentric contraction are only now becoming clearer. Eccentric contractions play an important role in everyday human movements, including mobility, stability, and muscle strength. Shortly after the sliding filament theory of muscle contraction was introduced, there was a reluctant recognition that muscle behaved as if it contained an "elastic" filament. Jean Hanson and Hugh Huxley referred to this structure as the "S-filament," though their concept gained little traction. This additional filament, the giant titin protein, was identified several decades later, and its roles in muscle contraction are still being discovered. Recent research has demonstrated that, like activation of thin filaments by calcium, titin is also activated in muscle sarcomeres by mechanisms only now being elucidated. The mdm mutation in mice appears to prevent activation of titin, and is a promising model system for investigating mechanisms of titin activation. Titin stiffness appears to increase with muscle force production, providing a mechanism that explains two fundamental properties of eccentric contractions: their high force and low energetic cost. The high force and low energy cost of eccentric contractions makes them particularly well suited for athletic training and rehabilitation. Eccentric exercise is commonly prescribed for treatment of a variety of conditions including sarcopenia, osteoporosis, and tendinosis. Use of eccentric exercise in rehabilitation and athletic training has exploded to include treatment for the elderly, as well as muscle and bone density maintenance for astronauts during long-term space travel. For exercise intolerance and many types of sports injuries, experimental evidence suggests that interventions involving eccentric exercise are demonstrably superior to conventional concentric interventions. Future work promises to advance our understanding of the molecular mechanisms that confer high force and low energy cost to eccentric contraction, as well as signaling mechanisms responsible for the beneficial effects of eccentric exercise in athletic training and rehabilitation.
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Affiliation(s)
| | | | - Kiisa C. Nishikawa
- Department of Biological Sciences, Center for Bioengineering Innovation, Northern Arizona UniversityFlagstaff, AZ, USA
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Maffetone PB, Rivera-Dominguez I, Laursen PB. Overfat and Underfat: New Terms and Definitions Long Overdue. Front Public Health 2017; 4:279. [PMID: 28097119 PMCID: PMC5206235 DOI: 10.3389/fpubh.2016.00279] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2016] [Accepted: 12/06/2016] [Indexed: 12/25/2022] Open
Abstract
For the first time in human history, the number of obese people worldwide now exceeds those who are underweight. However, it is possible that there is an even more serious problem-an overfat pandemic comprised of people who exhibit metabolic health impairments associated with excess fat mass relative to lean body mass. Many overfat individuals, however, are not necessarily classified clinically as overweight or obese, despite the common use of body mass index as the clinical classifier of obesity and overweight. The well-documented obesity epidemic may merely be the tip of the overfat iceberg. The counterpart to the overfat condition is the underfat state, also a common and dangerous health circumstance associated with chronic illness and starvation. Currently (and paradoxically), high rates of obesity and overweight development coexist with undernutrition in developing countries. Studies in cognitive linguistics suggest that accurate, useful, and unintimidating terminology regarding abnormal body fat conditions could help increase a person's awareness of their situation, helping the process of implementing prevention and simple remedies. Our contention is that promoting the terms "overfat" and "underfat" to describe body composition states to the point where they enter into common usage may help in creating substantive improvements in world health.
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Affiliation(s)
| | | | - Paul B. Laursen
- Sports Performance Research Institute New Zealand (SPRINZ), AUT University, Auckland, New Zealand
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Santos GL, García-Salazar LF, Souza MB, Oliveira AB, Camargo PR, Russo TL. Torque steadiness and muscle activation are bilaterally impaired during shoulder abduction and flexion in chronic post-stroke subjects. J Electromyogr Kinesiol 2016; 30:151-60. [PMID: 27451360 DOI: 10.1016/j.jelekin.2016.07.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 06/30/2016] [Accepted: 07/05/2016] [Indexed: 01/05/2023] Open
Abstract
OBJECTIVE To characterize sensorimotor control and muscle activation in the shoulder of chronic hemiparetic during abduction and flexion in maximal and submaximal isometric contractions. Furthermore, to correlate submaximal sensorimotor control with motor impairment and degree of shoulder subluxation. METHODS Thirteen chronic hemiparetic post-stroke age-gender matched with healthy were included. Isometric torques were assessed using a dynamometer. Electromyographic activity of the anterior and middle deltoid, upper trapezius, pectoralis major and serratus anterior muscles were collected. Variables were calculated for torque: peak, time to target, standard deviation (SD), coefficient of variation (CV), and standard error (RMSE); for muscle activity: maximum and minimum values, range and coefficient of activation. Motor impairment was determined by Fugl-Meyer and shoulder subluxation was measured with a caliper. RESULTS Paretic and non-paretic limbs reduced peak and muscle activation during maximal isometric contraction. Paretic limb generated lower force when compared with non-paretic and control. Paretic and non-paretic presented higher values of SD, CV, RMSE, and CV for prime mover muscles and minimum values for all muscles during steadiness. No correlation was found between sensorimotor control, motor impairment and shoulder subluxation. CONCLUSION Chronic hemiparetic presented bilateral deficits in sensorimotor and muscle control during maximal and submaximal shoulder abduction and flexion.
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Affiliation(s)
- Gabriela Lopes Santos
- Department of Physiotherapy, Federal University of São Carlos (UFSCar), São Carlos, SP, Brazil.
| | - Luisa Fernanda García-Salazar
- Department of Physiotherapy, Federal University of São Carlos (UFSCar), São Carlos, SP, Brazil; Physical Therapy Program, School of Medicine and Health Science, University of Rosario, Bogotá, D.C., Colombia
| | - Matheus Bragança Souza
- Department of Physiotherapy, Federal University of São Carlos (UFSCar), São Carlos, SP, Brazil
| | - Ana Beatriz Oliveira
- Department of Physiotherapy, Federal University of São Carlos (UFSCar), São Carlos, SP, Brazil
| | - Paula Rezende Camargo
- Department of Physiotherapy, Federal University of São Carlos (UFSCar), São Carlos, SP, Brazil
| | - Thiago Luiz Russo
- Department of Physiotherapy, Federal University of São Carlos (UFSCar), São Carlos, SP, Brazil
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Lindstedt SL. Skeletal muscle tissue in movement and health: positives and negatives. J Exp Biol 2016; 219:183-8. [DOI: 10.1242/jeb.124297] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
ABSTRACT
The history of muscle physiology is a wonderful lesson in ‘the scientific method’; our functional hypotheses have been limited by our ability to decipher (observe) muscle structure. The simplistic understanding of how muscles work made a large leap with the remarkable insights of A. V. Hill, who related muscle force and power to shortening velocity and energy use. However, Hill's perspective was largely limited to isometric and isotonic contractions founded on isolated muscle properties that do not always reflect how muscles function in vivo. Robert Josephson incorporated lengthening contractions into a work loop analysis that shifted the focus to dynamic muscle function, varying force, length and work done both by and on muscle during a single muscle work cycle. It became apparent that muscle is both a force generator and a spring. Titin, the missing filament in the sliding filament model, is a muscle spring, which functions very differently in cardiac versus skeletal muscle; its possible role in these two muscle types is discussed relative to their contrasting function. The good news for those of us who choose to work on skeletal muscle is that muscle has been reluctant to reveal all of its secrets.
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Affiliation(s)
- Stan L. Lindstedt
- Northern Arizona University, Department of Biological Sciences andCenter for Bioengineering Innovation, Flagstaff, AZ 86011-4165, USA
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Adams GR, Bamman MM. Characterization and regulation of mechanical loading-induced compensatory muscle hypertrophy. Compr Physiol 2013; 2:2829-70. [PMID: 23720267 DOI: 10.1002/cphy.c110066] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
In mammalian systems, skeletal muscle exists in a dynamic state that monitors and regulates the physiological investment in muscle size to meet the current level of functional demand. This review attempts to consolidate current knowledge concerning development of the compensatory hypertrophy that occurs in response to a sustained increase in the mechanical loading of skeletal muscle. Topics covered include: defining and measuring compensatory hypertrophy, experimental models, loading stimulus parameters, acute responses to increased loading, hyperplasia, myofiber-type adaptations, the involvement of satellite cells, mRNA translational control, mechanotransduction, and endocrinology. The authors conclude with their impressions of current knowledge gaps in the field that are ripe for future study.
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Affiliation(s)
- Gregory R Adams
- Department of Physiology and Biophysics, University of California Irvine, Irvine, California, USA.
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Chamari K, Laffaye G, Ardigò LP, Padulo J. Concentric and eccentric exercise. THE JOURNAL OF PAIN 2013; 14:1531-2. [PMID: 24182661 DOI: 10.1016/j.jpain.2013.07.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Revised: 06/01/2013] [Accepted: 07/03/2013] [Indexed: 11/17/2022]
Affiliation(s)
- Karim Chamari
- Research and Education Centre, Aspetar, Qatar; Orthopaedic and Sports Medicine Hospital, Doha, Qatar; Tunisian Research Laboratory "Sports Performance Optimization" National Center of Medicine and Science in Sport, Tunis, Tunisia
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Padulo J, Laffaye G, Chamari K. Concentric and eccentric: muscle contraction or exercise? ACTA PHYSIOLOGICA HUNGARICA 2013; 100:355-6. [PMID: 24058092 DOI: 10.1556/aphysiol.100.2013.3.12] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Affiliation(s)
- J Padulo
- University of "Tor Vergata" Faculty of Medicine and Surgery Rome Italy National Center of Medicine and Science in Sport Tunisian Research Laboratory, "Sports Performance Optimization" Tunis Tunisia
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Isner-Horobeti ME, Dufour SP, Vautravers P, Geny B, Coudeyre E, Richard R. Eccentric Exercise Training: Modalities, Applications and Perspectives. Sports Med 2013; 43:483-512. [DOI: 10.1007/s40279-013-0052-y] [Citation(s) in RCA: 121] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Muscular dystrophy in dysferlin-deficient mouse models. Neuromuscul Disord 2013; 23:377-87. [DOI: 10.1016/j.nmd.2013.02.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Revised: 01/09/2013] [Accepted: 02/05/2013] [Indexed: 11/17/2022]
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Jackson MC, Brown LE, Coburn JW, Judelson DA, Cullen-Carroll N. Towards Standardization of the Nomenclature of Resistance Training Exercises. J Strength Cond Res 2013; 27:1441-9. [DOI: 10.1519/jsc.0b013e318289168d] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Randazzo D, Giacomello E, Lorenzini S, Rossi D, Pierantozzi E, Blaauw B, Reggiani C, Lange S, Peter AK, Chen J, Sorrentino V. Obscurin is required for ankyrinB-dependent dystrophin localization and sarcolemma integrity. ACTA ACUST UNITED AC 2013; 200:523-36. [PMID: 23420875 PMCID: PMC3575540 DOI: 10.1083/jcb.201205118] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Obscurin contributes to the organization of subsarcolemma microtubules, localization of dystrophin at costameres, and maintenance of sarcolemmal integrity in skeletal muscle fibers. Obscurin is a large myofibrillar protein that contains several interacting modules, one of which mediates binding to muscle-specific ankyrins. Interaction between obscurin and the muscle-specific ankyrin sAnk1.5 regulates the organization of the sarcoplasmic reticulum in striated muscles. Additional muscle-specific ankyrin isoforms, ankB and ankG, are localized at the subsarcolemma level, at which they contribute to the organization of dystrophin and β-dystroglycan at costameres. In this paper, we report that in mice deficient for obscurin, ankB was displaced from its localization at the M band, whereas localization of ankG at the Z disk was not affected. In obscurin KO mice, localization at costameres of dystrophin, but not of β-dystroglycan, was altered, and the subsarcolemma microtubule cytoskeleton was disrupted. In addition, these mutant mice displayed marked sarcolemmal fragility and reduced muscle exercise tolerance. Altogether, the results support a model in which obscurin, by targeting ankB at the M band, contributes to the organization of subsarcolemma microtubules, localization of dystrophin at costameres, and maintenance of sarcolemmal integrity.
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Affiliation(s)
- Davide Randazzo
- Molecular Medicine Section, Department of Molecular and Developmental Medicine, University of Siena, 53100 Siena, Italy
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Chen TCC, Chen HL, Pearce AJ, Nosaka K. Attenuation of eccentric exercise-induced muscle damage by preconditioning exercises. Med Sci Sports Exerc 2013; 44:2090-8. [PMID: 22688830 DOI: 10.1249/mss.0b013e31825f69f3] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
PURPOSE This study compared the effect of an initial exercise consisting of either low-intensity eccentric or maximal isometric contractions (ISOs) on protective effect against maximal eccentric contraction (MaxECC)-induced muscle damage. METHODS Untrained young men were placed into one of five groups (n = 13 per group): MaxECC, 10% ECC, 20% ECC, 90° ISO, and 20° ISO. The MaxECC, 10% ECC, and 20% ECC groups performed 30 ECCs of the elbow flexors using a dumbbell equivalent to 100%, 10%, and 20% of maximal voluntary isometric contraction strength, respectively. The 90° ISO and 20° ISO groups performed 30 ISOs at 90° and 20° of elbow flexion, respectively. Three weeks later, all subjects performed 30 MaxECCs with the arm used for the first bout. Changes in maximal voluntary isometric and concentric contraction strength, range of motion, upper arm circumference, plasma creatine kinase and myoglobin concentration, and muscle soreness before and for 5 d after the first and second exercise bouts were compared among groups by a two-way repeated-measure ANOVA. RESULTS Changes in all measures after the first bout were smaller (P < 0.05) for 10% ECC, 20% ECC, 90° ISO, and 20° ISO groups compared with MaxECC group, and the changes were smaller (P < 0.05) for 10% ECC and 90° ISO than 20° ISO and 20% ECC groups. When compared with the first bout of MaxECC group, changes in the measures after the second bout were smaller for 20% ECC and 20° ISO groups with greater protective effect evident for 20° ISO group, but the protective effect conferred by these was smaller (P < 0.05) compared with MaxECCs. CONCLUSION These results suggest that there is threshold intensity for ECCs to confer protective effect, and ISOs at a long muscle length provide preconditioning effect.
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Cronin NJ, Prilutsky BI, Lichtwark GA, Maas H. Does ankle joint power reflect type of muscle action of soleus and gastrocnemius during walking in cats and humans? J Biomech 2013; 46:1383-6. [PMID: 23538001 DOI: 10.1016/j.jbiomech.2013.02.023] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Revised: 02/27/2013] [Accepted: 02/28/2013] [Indexed: 12/01/2022]
Abstract
The main objective of this paper is to highlight the difficulties of identifying shortening and lengthening contractions based on analysis of power produced by resultant joint moments. For that purpose, we present net ankle joint powers and muscle fascicle/muscle-tendon unit (MTU) velocities for medial gastrocnemius (MG) and soleus (SO) muscles during walking in species of different size (humans and cats). For the cat, patterns of ankle joint power and MTU velocity of MG and SO during stance were similar: negative power (ankle moment×angular velocity<0), indicating absorption of mechanical energy, was associated with MTU lengthening, and positive power (generation of mechanical energy) was found during MTU shortening. This was also found for the general fascicle velocity pattern in SO. In contrast, substantial differences between ankle joint power and fascicle velocity patterns were observed for MG muscle. In humans, like cats, the patterns of ankle joint power and MTU velocity of SO and MG were similar. Unlike the cat, there were substantial differences between patterns of fascicle velocity and ankle joint power during stance in both muscles. These results indicate that during walking, only a small fraction of mechanical work of the ankle moment is either generated or absorbed by the muscle fascicles, thus confirming the contribution of in-series elastic structures and/or energy transfer via two-joint muscles. We conclude that ankle joint negative power does not necessarily indicate eccentric action of muscle fibers and that positive power cannot be exclusively attributed to muscle concentric action, especially in humans.
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Affiliation(s)
- Neil J Cronin
- Neuromuscular Research Centre, Department of Biology of Physical Activity, University of Jyväskylä, Finland
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Davis Hammonds AL, Laudner KG, McCaw S, McLoda TA. Acute lower extremity running kinematics after a hamstring stretch. J Athl Train 2013; 47:5-14. [PMID: 22488225 DOI: 10.4085/1062-6050-47.1.5] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
CONTEXT Limited passive hamstring flexibility might affect kinematics, performance, and injury risk during running. Preactivity static straight-leg raise stretching often is used to gain passive hamstring flexibility. OBJECTIVE To investigate the acute effects of a single session of passive hamstring stretching on pelvic, hip, and knee kinematics during the swing phase of running. DESIGN Randomized controlled clinical trial. SETTING Biomechanics research laboratory. PATIENTS OR OTHER PARTICIPANTS Thirty-four male (age = 21.2 ± 1.4 years) and female (age = 21.3 ± 2.0 years) recreational athletes. INTERVENTION(S) Participants performed treadmill running pretests and posttests at 70% of their age-predicted maximum heart rate. Pelvis, hip, and knee joint angles during the swing phase of 5 consecutive gait cycles were collected using a motion analysis system. Right and left hamstrings of the intervention group participants were passively stretched 3 times for 30 seconds in random order immediately after the pretest. Control group participants performed no stretching or movement between running sessions. MAIN OUTCOME MEASURE(S) Six 2-way analyses of variance to determine joint angle differences between groups at maximum hip flexion and maximum knee extension with an α level of .008. RESULTS Flexibility increased between pretest and posttest in all participants (F(1,30) = 80.61, P < .001). Anterior pelvic tilt (F(1,30) = 0.73, P = .40), hip flexion (F(1,30) = 2.44, P = .13), and knee extension (F(1,30) = 0.06, P = .80) at maximum hip flexion were similar between groups throughout testing. Anterior pelvic tilt (F(1,30) = 0.69, P = .41), hip flexion (F(1,30) = 0.23, P = .64), and knee extension (F(1,30) = 3.38, P = .62) at maximum knee extension were similar between groups throughout testing. Men demonstrated greater anterior pelvic tilt than women at maximum knee extension (F(1,30) = 13.62, P = .001). CONCLUSIONS A single session of 3 straight-leg raise hamstring stretches did not change pelvis, hip, or knee running kinematics.
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Abstract
OBJECTIVE The purpose of this review is to describe the physiologic changes that occur in the musculoskeletal system during aging and the common injuries that occur in the lower extremity as a consequence of these changes. Several clinical presentations are addressed, and their differential diagnoses are discussed with an emphasis on the most likely injury for each presentation. CONCLUSION A unique quality of the newly aging group of people referred to as baby boomers is their expectation to continue exercising as they grow older, thus the incidence of exercise-induced injuries among older people is increasing. The concepts behind factors that predispose older athletes to certain pathologic conditions that affect the muscles, tendons, and bones of the lower extremity must be understood.
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Chen TC, Tseng WC, Huang GL, Chen HL, Tseng KW, Nosaka K. Low-intensity eccentric contractions attenuate muscle damage induced by subsequent maximal eccentric exercise of the knee extensors in the elderly. Eur J Appl Physiol 2012; 113:1005-15. [DOI: 10.1007/s00421-012-2517-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2012] [Accepted: 09/27/2012] [Indexed: 10/27/2022]
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Zeppetzauer M, Drexel H, Vonbank A, Rein P, Aczel S, Saely CH. Eccentric endurance exercise economically improves metabolic and inflammatory risk factors. Eur J Prev Cardiol 2012; 20:577-84. [PMID: 22505055 DOI: 10.1177/2047487312444236] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
INTRODUCTION Exercise is a cornerstone of cardiovascular prevention. Because many individuals are not willing or not able to perform regular exercise, new methods of exercise (like eccentric exercise) are necessary. Eccentric endurance exercise is supposed to be less strenuous than concentric exercise but its effects on glucose and lipid metabolism in relation to energy expenditure are unclear. METHODS We randomly allocated 45 healthy sedentary individuals to one of two groups, each hiking upwards or downwards for 2 months, with a crossover for a further 2 months; for the opposite way, a cable car was used. The difference in altitude was 540 metres; the distance was covered between three and five times a week. Energy expenditure was assessed for each hiking period. RESULTS Both eccentric and concentric endurance exercise improved glucose tolerance vs. baseline (by 4.1%, p = 0.136; 6.2%, p = 0.023, respectively). Of note, adjustment for energy expenditure per exercise unit (127 ± 22 kcal/unit with eccentric and 442 ± 78 kcal/unit with concentric exercise) revealed a significantly greater improvement of glucose tolerance per kilocalorie spent by eccentric than by concentric exercise (4-times more economical; 0.1123 mg h/dl/kcal vs. 0.0245 mg h/dl/kcal; p = 0.038). Also the decrease of low-density lipoprotein (LDL) cholesterol per kilocalorie spent was significantly stronger with eccentric exercise (0.0982 mg/dl/kcal vs. 0.0346 mg/dl/kcal, p = 0.014). Serum levels of C-reactive protein and creatine kinase activity were reduced in both groups. CONCLUSION Eccentric endurance exercise economically improves glucose tolerance and LDL cholesterol. It therefore is a promising new exercise modality for individuals who are not able to participate in more strenuous exercise regimens.
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Affiliation(s)
- Markus Zeppetzauer
- Vorarlberg Institute for Vascular Investigation and Treatment, Feldkirch, Austria
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Training implications of maximal forces on a computer-controlled and motor-driven leg press by age group, sex, footplate direction, and speed. Exp Gerontol 2012; 47:295-303. [DOI: 10.1016/j.exger.2012.01.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2011] [Revised: 12/23/2011] [Accepted: 01/13/2012] [Indexed: 11/18/2022]
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Kuhtz-Buschbeck JP, Jing B. Activity of upper limb muscles during human walking. J Electromyogr Kinesiol 2011; 22:199-206. [PMID: 21945656 DOI: 10.1016/j.jelekin.2011.08.014] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2011] [Revised: 08/31/2011] [Accepted: 08/31/2011] [Indexed: 11/19/2022] Open
Abstract
The EMG activity of upper limb muscles during human gait has rarely been studied previously. It was examined in 20 normal volunteers in four conditions: walking on a treadmill (1) with unrestrained natural arm swing (Normal), (2) while volitionally holding the arms still (Held), (3) with the arms immobilized (Bound), and (4) with the arms swinging in phase with the ipsilateral legs, i.e. opposite-to-normal phasing (Anti-Normal). Normal arm swing involved weak rhythmical lengthening and shortening contractions of arm and shoulder muscles. Phasic muscle activity was needed to keep the unrestricted arms still during walking (Held), indicating a passive component of arm swing. An active component, possibly programmed centrally, existed as well, because some EMG signals persisted when the arms were immobilized during walking (Bound). Anti-Normal gait involved stronger EMG activity than Normal walking and was uneconomical. The present results indicate that normal arm swing has both passive and active components.
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Affiliation(s)
- Johann P Kuhtz-Buschbeck
- Institute of Physiology, Christian-Albrechts-Universität Kiel, Olshausenstr. 40, D 24098 Kiel, Germany.
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Markert CD, Ambrosio F, Call JA, Grange RW. Exercise and Duchenne muscular dystrophy: toward evidence-based exercise prescription. Muscle Nerve 2011; 43:464-78. [PMID: 21404285 DOI: 10.1002/mus.21987] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
To develop a rational framework for answering questions about the role of exercise in Duchenne muscular dystrophy (DMD), we focused on five pathophysiological mechanisms and offer brief hypotheses regarding how exercise may beneficially modulate pertinent cellular and molecular pathways. We aimed to provide an integrative overview of mechanisms of DMD pathology that may improve or worsen as a result of exercise. We also sought to stimulate discussion of what outcomes/dependent variables most appropriately measure these mechanisms, with the purpose of defining criteria for well-designed, controlled studies of exercise in DMD. The five mechanisms include pathways that are both intrinsic and extrinsic to the diseased muscle cells.
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Affiliation(s)
- Chad D Markert
- Wake Forest Institute for Regenerative Medicine, Medical Center Boulevard, Winston-Salem, North Carolina 27157, USA.
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Ramaswamy KS, Palmer ML, van der Meulen JH, Renoux A, Kostrominova TY, Michele DE, Faulkner JA. Lateral transmission of force is impaired in skeletal muscles of dystrophic mice and very old rats. J Physiol 2011; 589:1195-208. [PMID: 21224224 DOI: 10.1113/jphysiol.2010.201921] [Citation(s) in RCA: 175] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The dystrophin–glycoprotein complex (DGC) provides an essential link from the muscle fibre cytoskeleton to the extracellular matrix. In dystrophic humans and mdx mice, mutations in the dystrophin gene disrupt the structure of the DGC causing severe damage to muscle fibres. In frog muscles, transmission of force laterally from an activated fibre to the muscle surface occurs without attenuation, but lateral transmission of force has not been demonstrated in mammalian muscles. A unique ‘yoke' apparatus was developed that attached to the epimysium of muscles midway between the tendons and enabled the measurement of lateral force. We now report that in muscles of young wild-type (WT) mice and rats, compared over a wide range of longitudinal forces, forces transmitted laterally showed little or no decrement. In contrast, for muscles of mdx mice and very old rats, forces transmitted laterally were impaired severely. Muscles of both mdx mice and very old rats showed major reductions in the expression of dystrophin. We conclude that during contractions, forces developed by skeletal muscles of young WT mice and rats are transmitted laterally from fibre to fibre through the DGC without decrement. In contrast, in muscles of dystrophic or very old animals, disruptions in DGC structure and function impair lateral transmission of force causing instability and increased susceptibility of fibres to contraction-induced injury.
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Affiliation(s)
- Krishnan S Ramaswamy
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan 48109-2200, USA
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38
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McGinley C, Shafat A, Donnelly AE. Does Antioxidant Vitamin Supplementation Protect against Muscle Damage? Sports Med 2009; 39:1011-32. [DOI: 10.2165/11317890-000000000-00000] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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39
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Jönhagen S, Halvorsen K, Benoit DL. Muscle activation and length changes during two lunge exercises: implications for rehabilitation. Scand J Med Sci Sports 2009; 19:561-8. [DOI: 10.1111/j.1600-0838.2007.00692.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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40
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Winter EM, Fowler N. Exercise defined and quantified according to the Systeme International d'Unites. J Sports Sci 2009; 27:447-60. [PMID: 19253082 DOI: 10.1080/02640410802658461] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Sport and exercise scientists have a common focus: the scientific study of factors that influence our ability to perform exercise or physical activity. As a result, this ability is assessed and hence quantified. Accordingly, definitions of exercise and related terms and nomenclature that describe the performance of exercise must adhere to principles of science and satisfy the Systeme International d'Unites (SI) that was adopted universally in 1960. Frequently, these requirements are not met. The aims of this review are twofold: (1) to identify instances of non-compliance and (2) propose universal definitions of exercise and related terms and nomenclature that do conform to the SI and apply to exercise and physical activity that encompasses elite-standard competitive sport, activities of daily living, and clinical applications in rehabilitation and public health. A definition of exercise is offered: a potential disruption to homeostasis by muscle activity that is either exclusively, or in combination, concentric, eccentric or isometric.
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Affiliation(s)
- Edward M Winter
- Centre for Sport and Exercise Science, Sheffield Hallam University, Sheffield, UK.
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41
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Gea J, Zhu E, Gáldiz JB, Comtois N, Salazkin I, Antonio Fiz J, Grassino A. Functional Consequences of Eccentric Contractions of the Diaphragm. ACTA ACUST UNITED AC 2009. [DOI: 10.1016/s1579-2129(09)70777-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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42
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Gea J, Zhu E, Gáldiz JB, Comtois N, Salazkin I, Antonio Fiz J, Grassino A. Consecuencias de las contracciones excéntricas del diafragma sobre su función. Arch Bronconeumol 2009; 45:68-74. [PMID: 19232267 DOI: 10.1016/j.arbres.2008.04.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2007] [Accepted: 04/18/2008] [Indexed: 10/21/2022]
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43
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The aging of elite male athletes: age-related changes in performance and skeletal muscle structure and function. Clin J Sport Med 2008; 18:501-7. [PMID: 19001883 PMCID: PMC3928819 DOI: 10.1097/jsm.0b013e3181845f1c] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
OBJECTIVE The paper addresses the degree to which the attainment of the status as an elite athlete in different sports ameliorates the known age-related losses in skeletal muscle structure and function. DESIGN The retrospective design, based on comparisons of published data on former elite and masters athletes and data on control subjects, assessed the degree to which the attainment of elite and masters athlete status ameliorated the known age-related changes in skeletal muscle structure and function. SETTING Institutional. PARTICIPANTS Elite male athletes. INTERVENTIONS Participation in selected individual and team sports. MAIN OUTCOME MEASUREMENTS Strength, power, VO2max, and performance. RESULTS For elite athletes in all sports, as for the general population, age-related muscle atrophy begins at about 50 years of age. Despite the loss of muscle mass, elite athletes who maintain an active lifestyle age gracefully with few health problems. Conversely, those who lapse into inactivity regress toward general population norms for fitness, weight control, and health problems. Elite athletes in the dual and team sports have careers that rarely extend into their 30s. CONCLUSIONS Lifelong physical activity does not appear to have any impact on the loss in fiber number. The loss of fibers can be buffered to some degree by hypertrophy of fibers that remain. It is surprising that the performance of elite athletes in all sports appears to be impaired before the onset of the fiber loss. Even with major losses in physical capacity and muscle mass, the performance of elite and masters athletes is remarkable.
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44
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Liu D, Metter EJ, Ferrucci L, Roth SM. TNF promoter polymorphisms associated with muscle phenotypes in humans. J Appl Physiol (1985) 2008; 105:859-67. [PMID: 18635873 DOI: 10.1152/japplphysiol.90655.2008] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Tumor necrosis factor-alpha (TNF-alpha) is a potent catabolic factor to skeletal muscle. Single-nucleotide polymorphisms (SNPs) in the promoter region of the TNF-alpha coding gene, TNF, have been implicated in the interindividual variation in TNF-alpha production via transcriptional regulation. The present study investigated the association of muscle phenotypes with five TNF promoter SNPs, which potentially have biological significance. Female and male volunteers (n = 1,050) from the Baltimore Longitudinal Study of Aging were genotyped, and their regional and total body muscle mass, and arm and leg muscle strength were measured. Results indicated that putative high-expression alleles at positions -1031 and -863, individually or in combination in the haplotype 1031C-863A-857C-308G-238G, were associated with lower muscle mass in men. Specifically, carriers of -1031C, compared with noncarriers, exhibited lower arm muscle mass (6.4 +/- 0.1 vs. 6.8 +/- 0.1 kg, P = 0.01) and appendicular skeletal muscle mass (ASM) (24.3 +/- 0.4 vs. 25.4 +/- 0.2 kg, P = 0.02), with leg muscle mass and the ASM index (ASMI; kg/m(2)) also tending to be lower (P = 0.06 and 0.07). Similarly, -863A allele carriers (linked with -1031), compared with noncarriers, exhibited lower arm muscle mass (6.4 +/- 0.1 vs. 6.8 +/- 0.1 kg, P = 0.04). Carriers of the haplotype 1031C-863A-857C-308G-238G, compared with noncarriers, exhibited lower arm muscle mass (6.3 +/- 0.2 vs. 6.8 +/- 0.1 kg, P < 0.01), trunk muscle mass (25.7 +/- 0.5 vs. 26.9 +/- 0.3 kg, P < 0.05), and ASM (24.1 +/- 0.5 vs. 25.3 +/- 0.2 kg, P < 0.025), with tendencies for lower leg muscle mass and ASMI (P = 0.07 and 0.08). Results indicate that genetic variation in the TNF locus may contribute to the interindividual variation in muscle phenotypes in men.
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Affiliation(s)
- Dongmei Liu
- Dept. of Kinesiology, Univ. of Maryland, College Park, MD 20742-2611, USA
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45
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Lynch GS, Faulkner JA, Brooks SV. Force deficits and breakage rates after single lengthening contractions of single fast fibers from unconditioned and conditioned muscles of young and old rats. Am J Physiol Cell Physiol 2008; 295:C249-56. [PMID: 18508906 DOI: 10.1152/ajpcell.90640.2007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The deficit in force generation is a measure of the magnitude of damage to sarcomeres caused by lengthening contractions of either single fibers or whole muscles. In addition, permeabilized single fibers may suffer breakages. Our goal was to understand the interaction between breakages and force deficits in "young" and "old" permeabilized single fibers from control muscles of young and old rats and "conditioned" fibers from muscles that completed a 6-wk program of in vivo lengthening contractions. Following single lengthening contractions of old-control fibers compared with young-control fibers, the twofold greater force deficits at a 10% strain support the concept of an age-related increase in the susceptibility of fibers to mechanical damage. In addition, the much higher breakage rates for old fibers at all strains tested indicate an increase with aging in the number of fibers at risk of being severely injured during any given stretch. Following the 6-wk program of lengthening contractions, young-conditioned fibers and old-conditioned fibers were not different with respect to force deficit or the frequency of breakages. A potential mechanism for the increased resistance to stretch-induced damage of old-conditioned fibers is that, through intracellular damage and subsequent degeneration and regeneration, weaker sarcomeres were replaced by stronger sarcomeres. These data indicate that, despite the association of high fiber breakage rates and large force deficits with aging, the detrimental characteristics of old fibers were improved by a conditioning program that altered both sarcomeric characteristics as well as the overall structural integrity of the fibers.
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Affiliation(s)
- Gordon S Lynch
- Basic and Clinical Myology Laboratory, Department of Physiology, The University of Melbourne, Victoria, Australia.
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46
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Magnitude of sarcomere extension correlates with initial sarcomere length during lengthening of activated single fibers from soleus muscle of rats. Biophys J 2008; 95:1890-901. [PMID: 18469072 DOI: 10.1529/biophysj.107.118109] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A laser-diffraction technique was developed that rapidly reports the lengths of sarcomeres (L(s)) in serially connected sectors of permeabilized single fibers. The apparatus translates a laser beam along the entire length of a fiber segment within 2 ms, with brief stops at each of 20 contiguous sectors. We tested the hypothesis that during lengthening contractions, when maximally activated fibers are stretched, sectors that contain the longer sarcomeres undergo greater increases in L(s) than those containing shorter sarcomeres. Fibers (n = 16) were obtained from the soleus muscles of adult male rats and the middle portions (length = 1.05 +/- 0.11 mm; mean +/- SD) were investigated. Single stretches of strain 27% and a strain rate of 54% s(-1) were initiated at maximum isometric stress and resulted in a 19 +/- 9% loss in isometric stress. The data on L(s) revealed that 1), the stretch was not distributed uniformly among the sectors, and 2), during the stretch, sectors at long L(s) before the stretch elongated more than those at short lengths. The findings support the hypothesis that during stretches of maximally activated skeletal muscles, sarcomeres at longer lengths are more susceptible to damage by excessive strain.
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47
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Marqueste T, Giannesini B, Fur YL, Cozzone PJ, Bendahan D. Comparative MRI analysis of T2 changes associated with single and repeated bouts of downhill running leading to eccentric-induced muscle damage. J Appl Physiol (1985) 2008; 105:299-307. [PMID: 18450983 DOI: 10.1152/japplphysiol.00738.2007] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Although the exact mechanisms are still unclear, it is commonly acknowledged that acute eccentric exercise alters muscle performance, whereas the repetition of successive bouts leads to the disappearance of the deleterious signs. To clarify this issue, we measured blood creatine kinase and lactate dehydrogenase activities and proton transverse relaxation time (T2) in various leg muscles 72 h after single and repeated bouts of exhausting downhill running sessions (-15 degrees , 1.5 km/h) with either 4 or 7 days elapsed between bouts. After a single exercise bout, T2 and enzyme activities initially increased and recovered rapidly. When exercise bouts were repeated over a short time period (4 days), initial changes did not recover and endurance time throughout additional exercise sessions was significantly reduced. On the contrary, with a longer resting time between exercises (7 days), the endurance time of additional running sessions was significantly longer and muscle changes (T2 increase, muscle edema, and enzyme activity changes) slowly and completely reversed. Significant correlations were found between T2 changes and enzyme activities. T2 changes in the soleus and gastrocnemius muscle heads were differently affected by lengthening contractions, suggesting a muscle specificity and indicating that muscle alterations might be linked to different anatomical properties, such as fiber pennation angles, typology, and/or the exhausting nature of the downhill running sessions. We documented a "less muscle injury" effect due to the repetition of exercise bouts at a low frequency (i.e., 1 session per week) in accordance with the delayed muscle inflammation. This effect was not observed when the between-exercise resting time was shorter.
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Affiliation(s)
- Tanguy Marqueste
- Centre de Résonance Magnétique Biologique et Médicale, Unite Mixte de Recherche (UMR) Centre National de la Recherche Scientifique (CNRS) 6612, Faculté de Médecine de Marseille, Marseille, France.
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48
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Drexel H, Saely CH, Langer P, Loruenser G, Marte T, Risch L, Hoefle G, Aczel S. Metabolic and anti-inflammatory benefits of eccentric endurance exercise - a pilot study. Eur J Clin Invest 2008; 38:218-26. [PMID: 18339002 DOI: 10.1111/j.1365-2362.2008.01937.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND Eccentric endurance exercise (e.g. hiking downwards) is less strenuous than concentric exercise (e.g. hiking upwards) but its potential to reduce cardiovascular risk is unknown. MATERIALS AND METHODS We randomly allocated 45 healthy sedentary individuals (16 men and 29 women, mean age 48 years) to one of two groups, one beginning with two months of hiking upwards, the other with two months of hiking downwards the same route, with a crossover for a further two months. For the opposite way, a cable car was used where compliance was recorded electronically. The difference in altitude was 540 metres; the distance was covered three to five times a week. Fasting and postprandial metabolic profiles were obtained at baseline and after the two month periods of eccentric and concentric exercise, respectively. RESULTS Forty-two of the 45 participants completed the study; the compliance rate was therefore 93%. Compared with baseline, eccentric exercise lowered total cholesterol (by 4.1%; P = 0.026), low-density lipoprotein (LDL) cholesterol (by 8.4%, P = 0.001), Apolipoprotein B/Apolipoprotein A1 ratio (by 10.9%, P < 0.001), homeostasis model assessment of insulin resistance scores (by 26.2%, P = 0.017) and C-reactive protein (by 30.0%; P = 0.007); the magnitude of these changes was comparable to that of concentric exercise. Eccentric exercise improved glucose tolerance (by 6.2%, P = 0.023), whereas concentric exercise improved triglyceride tolerance (by 14.9%, P = 0.022). CONCLUSIONS Eccentric endurance exercise is a promising new exercise modality with favourable metabolic and anti-inflammatory effects and is well applicable to sedentary individuals.
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Affiliation(s)
- H Drexel
- Vorarlberg Institute for Vascular Investigation and Treatment, Feldkirch, Austria
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49
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Withrow TJ, Huston LJ, Wojtys EM, Ashton-Miller JA. Effect of varying hamstring tension on anterior cruciate ligament strain during in vitro impulsive knee flexion and compression loading. J Bone Joint Surg Am 2008; 90:815-23. [PMID: 18381320 PMCID: PMC2663321 DOI: 10.2106/jbjs.f.01352] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
BACKGROUND The hamstring muscles are well positioned to limit both anterior tibial translation and anterior cruciate ligament strain during the knee flexion phase of a jump landing. We hypothesized that systematically increasing or decreasing hamstring tension during the knee flexion phase of a simulated jump landing would significantly affect peak relative strain in the anterior cruciate ligament. METHODS Ten cadaveric knees from four male and six female donors (mean age [and standard deviation] at the time of death, 60.3 +/- 23.6 years) were mounted in a custom fixture to initially position the specimen in 25 degrees of knee flexion and simulate axial impulsive loading averaging 1700 N to cause an increase in knee flexion. Quadriceps, hamstring, and gastrocnemius muscle forces were simulated with use of pretensioned linear springs, with the tension in the hamstrings arranged to be increased, held constant, decreased, at "baseline," or absent during knee flexion. Impulsive loading applied along the tibia and femur was monitored with use of triaxial load transducers, while uniaxial load cells monitored quadriceps and medial and lateral hamstring forces. Relative strain in the anterior cruciate ligament was measured with use of a differential variable reluctance transducer, and tibiofemoral kinematics were measured optoelectronically. For each specimen, anterior cruciate ligament strains were recorded over eighty impact trials: ten preconditioning trials, ten "baseline" trials involving decreasing hamstring tension performed before and after three sets of ten trials conducted with increasing hamstring tension, constant hamstring tension, or no hamstring tension. Peak relative strains in the anterior cruciate ligament were normalized for comparison across specimens. RESULTS Increasing hamstring force during the knee flexion landing phase decreased the peak relative strain in the anterior cruciate ligament by >70% compared with the baseline condition (p = 0.005). Neither a constant hamstring muscle force nor the absence of a hamstring force significantly changed the peak strain in the anterior cruciate ligament relative to the baseline condition. CONCLUSIONS Increasing hamstring muscle force during the knee flexion phase of a simulated jump landing significantly reduces the peak relative strain in the anterior cruciate ligament in vitro.
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Affiliation(s)
- Thomas J. Withrow
- Department of Mechanical Engineering, Vanderbilt University, VU Station B 351592, Nashville, TN 37235. E-mail address:
| | - Laura J. Huston
- Vanderbilt Orthopaedic Institute, Medical Center East, South Tower, Suite 4200, Nashville, TN 37232-8774. E-mail address:
| | - Edward M. Wojtys
- MedSport, 24 Frank Lloyd Wright Drive, Ann Arbor, MI 48106. E-mail address:
| | - James A. Ashton-Miller
- Department of Mechanical Engineering and Applied Mechanics, Biomechanics Research Laboratory, University of Michigan, G.G. Brown 3208, Ann Arbor, MI 48109-2125. E-mail address:
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50
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Faulkner JA, Ng R, Davis CS, Li S, Chamberlain JS. Diaphragm muscle strip preparation for evaluation of gene therapies in mdx mice. Clin Exp Pharmacol Physiol 2008; 35:725-9. [PMID: 18215182 DOI: 10.1111/j.1440-1681.2007.04865.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
1. Duchenne muscular dystrophy (DMD), a severe muscle wasting disease of young boys with an incidence of one in every 3000, results from a mutation in the gene that encodes dystrophin. The absence of dystrophin expression in skeletal muscles and heart results in the degeneration of muscle fibres and, consequently, severe muscle weakness and wasting. The mdx mouse discovered in 1984, with some adjustments for differences, has proven to be an invaluable model for scientific investigations of dystrophy. 2. The development of the diaphagm strip preparation provided an ideal experimental model for investigations of skeletal muscle impairments in structure and function induced by interactions of disease- and age-related factors. Unlike the limb muscles of the mdx mouse, which show adaptive changes in structure and function, the diaphragm strip preparation reflects accurately the deterioration in muscle structure and function observed in boys with DMD. 3. The advent of sophisticated servo motors and force transducers interfaced with state-of-the-art software packages to drive complex experimental designs during the 1990s greatly enhanced the capability of the mdx mouse and the diaphragm strip preparation to evaluate more accurately the impact of the disease on the structure-function relationships throughout the life span of the mouse. 4. Finally, during the 1990s and through the early years of the 21st century, many promising, sophisticated genetic techniques have been designed to ameliorate the devastating impact of muscular dystrophy on the structure and function of skeletal muscles. During this period of rapid development of promising genetic therapies, the combination of the mdx mouse and the diaphragm strip preparation has provided an ideal model for the evaluation of the success, or failure, of these genetic techniques to improve dystrophic muscle structure, function or both. With the 2 year life span of the mdx mouse, the impact of age-related effects can be studied in this model.
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Affiliation(s)
- John A Faulkner
- Department of Molecular and Integrative Physiology, School of Medicine, University of Ann Arbor, Michigan 48109-2200, USA.
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