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Warneke K, Lohmann LH, Behm DG, Wirth K, Keiner M, Schiemann S, Wilke J. Effects of Chronic Static Stretching on Maximal Strength and Muscle Hypertrophy: A Systematic Review and Meta-Analysis with Meta-Regression. SPORTS MEDICINE - OPEN 2024; 10:45. [PMID: 38637473 PMCID: PMC11026323 DOI: 10.1186/s40798-024-00706-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Accepted: 03/26/2024] [Indexed: 04/20/2024]
Abstract
BACKGROUND Increases in maximal strength and muscle volume represent central aims of training interventions. Recent research suggested that the chronic application of stretch may be effective in inducing hypertrophy. The present systematic review therefore aimed to syntheisize the evidence on changes of strength and muscle volume following chronic static stretching. METHODS Three data bases were sceened to conduct a systematic review with meta-analysis. Studies using randomized, controlled trials with longitudinal (≥ 2 weeks) design, investigating strength and muscle volume following static stretching in humans, were included. Study quality was rated by two examiners using the PEDro scale. RESULTS A total of 42 studies with 1318 cumulative participants were identified. Meta-analyses using robust variance estimation showed small stretch-mediated maximal strength increases (d = 0.30 p < 0.001) with stretching duration and intervention time as significant moderators. Including all studies, stretching induced small magnitude, but significant hypertrophy effects (d = 0.20). Longer stretching durations and intervention periods as well as higher training frequencies revealed small (d = 0.26-0.28), but significant effects (p < 0.001-0.005), while lower dosage did not reach the level of significance (p = 0.13-0.39). CONCLUSIONS While of minor effectiveness, chronic static stretching represents a possible alternative to resistance training when aiming to improve strength and increase muscle size. As a dose-response relationship may exist, higher stretch durations and frequencies as well as long program durations should be further elaborated.
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Affiliation(s)
- Konstantin Warneke
- Institute of Human Movement Science, Sport and Health, University of Graz, Graz, Austria
- Department of Movement Sciences, University of Klagenfurt, Klagenfurt am Wörthersee, Austria
| | - Lars Hubertus Lohmann
- Department of Human Motion Science and Exercise Physiology, Friedrich Schiller University, 07743, Jena, Germany.
| | - David G Behm
- School of Human Kinetics and Recreation, Newfoundland and Labrador, Memorial University of Newfoundland, St. John's, Canada
| | - Klaus Wirth
- University of Applied Sciences Wiener Neustadt, Wiener Neustadt, Austria
| | - Michael Keiner
- Department of Sport Science, German University of Health & Sport, Ismaning, Germany
| | - Stephan Schiemann
- Institute of Exercise, Sport and Health, Leuphana University, Lüneburg, Germany
| | - Jan Wilke
- Department of Movement Sciences, University of Klagenfurt, Klagenfurt am Wörthersee, Austria
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Schilaty ND, McPherson AL, Nagai T, Bates NA. Differences in psychological readiness for return to sport after anterior cruciate ligament injury is evident in thigh musculature motor unit characteristics. BMJ Open Sport Exerc Med 2023; 9:e001609. [PMID: 37440978 PMCID: PMC10335479 DOI: 10.1136/bmjsem-2023-001609] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/26/2023] [Indexed: 07/15/2023] Open
Abstract
Background Following anterior cruciate ligament (ACL) injury, many athletes that undergo surgery and 6-9 months of rehabilitation struggle to return to sport. Evidence suggests that psychological factors contribute to this failure to return-to-sport. Objective Determine the motor control relationship between thigh musculature motor unit characteristics and psychological readiness to return to sport between ACL-injured and healthy controls. Study design A longitudinal cohort study. Methods Athletes longitudinally completed the ACL Return to Sport after Injury (ACL-RSI) survey and isometric strength measures with a measurement of electromyography (EMG) of the vastus lateralis, vastus medialis, biceps femoris, and semitendinosus. A score cut-off of 61 on the ACL-RSI was used to divide ACL-injured groups. EMG was decomposed to provide each identified motor unit's characteristics (amplitude, average firing rate, etc). Results Data demonstrated increased average firing rate for hamstrings (p<0.001), decreased average firing rate for vastus lateralis (p<0.001) and decreased motor unit size for both the quadriceps and hamstrings at return-to-sport post-ACL reconstruction compared with sex-matched and age-matched healthy controls (p<0.001). Furthermore, there were marked differences in disparate ACL-RSI scores between ACL-injured athletes. Conclusions At return to sport, ACL-injured athletes have major alterations of thigh musculature motor control, with smaller motor units used by those with low ACL-RSI scores. This study uniquely demonstrates objective thigh muscle motor unit characteristics that coincide with subjective reports of psychological readiness. This information will be important to address psychomotor complexes of injury for future rehabilitation protocols.
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Affiliation(s)
- Nathan D Schilaty
- Department of Neurosurgery & Brain Repair, University of South Florida Tampa Campus, Tampa, Florida, USA
- Medical Engineering, University of South Florida, Tampa, Florida, USA
- Center for Neuromusculoskeletal Research, University of South Florida, Tampa, Florida, USA
- Department of Orthopedic Surgery, Mayo Clinic, Rochester, Minnesota, USA
| | - April L McPherson
- Department of Orthopedic Surgery, Mayo Clinic, Rochester, Minnesota, USA
- Department of Orthopaedics, The Ohio State University, Columbus, Ohio, USA
- Emory Sports Performance and Research Center, Emory University, Atlanta, Georgia, USA
| | - Takashi Nagai
- Department of Orthopedic Surgery, Mayo Clinic, Rochester, Minnesota, USA
- Division of Military Performance, USARIEM, Natick, Massachusetts, USA
| | - Nathaniel A Bates
- Department of Orthopedic Surgery, Mayo Clinic, Rochester, Minnesota, USA
- Department of Orthopaedics, The Ohio State University, Columbus, Ohio, USA
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Warneke K, Keiner M, Hillebrecht M, Schiemann S. Influence of One Hour versus Two Hours of Daily Static Stretching for Six Weeks Using a Calf-Muscle-Stretching Orthosis on Maximal Strength. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:11621. [PMID: 36141890 PMCID: PMC9517223 DOI: 10.3390/ijerph191811621] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 09/07/2022] [Accepted: 09/14/2022] [Indexed: 06/16/2023]
Abstract
Rebuilding strength capacity is of crucial importance in rehabilitation since significant atrophy due to immobilization after injury and/or surgery can be assumed. To increase maximal strength (MSt), strength training is commonly used. The literature regarding animal studies show that long-lasting static stretching (LStr) interventions can also produce significant improvements in MSt with a dose-response relationship, with stretching times ranging from 30 min to 24 h per day; however, there is limited evidence in human studies. Consequently, the aim of this study is to investigate the dose-response relationship of long-lasting static stretching on MSt. A total of 70 active participants (f = 30, m = 39; age: 27.4 ± 4.4 years; height: 175.8 ± 2.1 cm; and weight: 79.5 ± 5.9 kg) were divided into three groups: IG1 and IG2 both performed unilateral stretching continuously for one (IG1) or two hours (IG2), respectively, per day for six weeks, while the CG served as the non-intervened control. MSt was determined in the plantar flexors in the intervened as well as in the non-intervened control leg to investigate the contralateral force transfer. Two-way ANOVA showed significant interaction effects for MSt in the intervened leg (ƞ2 = 0.325, p < 0.001) and in the contralateral control leg (ƞ2 = 0.123, p = 0.009), dependent upon stretching time. From this, it can be hypothesized that stretching duration had an influence on MSt increases, but both durations were sufficient to induce significant enhancements in MSt. Thus, possible applications in rehabilitation can be assumed, e.g., if no strength training can be performed, atrophy could instead be reduced by performing long-lasting static stretch training.
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Affiliation(s)
- Konstantin Warneke
- Institute for Exercise, Sport and Health, Leuphana University, 21335 Lüneburg, Germany
| | - Michael Keiner
- Department of Sport Science, German University of Health & Sport, 85737 Ismaning, Germany
| | - Martin Hillebrecht
- University Sports Center, University of Oldenburg, 26129 Oldenburg, Germany
| | - Stephan Schiemann
- Institute for Exercise, Sport and Health, Leuphana University, 21335 Lüneburg, Germany
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Ely IA, Jones EJ, Inns TB, Dooley S, Miller SBJ, Stashuk DW, Atherton PJ, Phillips BE, Piasecki M. Training induced improvements in knee extensor force accuracy are associated with reduced vastus lateralis motor unit firing variability. Exp Physiol 2022; 107:1061-1070. [PMID: 35923141 PMCID: PMC9542263 DOI: 10.1113/ep090367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Accepted: 07/28/2022] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? We aimed to determine levels of bilateral knee extensor force accuracy and any subsequent alterations to central and/or peripheral motor unit features, following 4 weeks of unilateral force accuracy training. What is the main finding and its importance? In the trained limb only, knee extensor force tracking accuracy improved with reduced motor unit firing rate variability in the vastus lateralis, and no change to neuromuscular junction transmission instability. Interventional strategies to improve force accuracy may be directed to older/clinical populations where such improvements may aid performance of daily living activities. ABSTRACT Background Muscle force output during sustained submaximal isometric contractions fluctuates around an average value and is partly influenced by variation in motor unit (MU) firing rates. MU firing rate (FR) variability seemingly reduces following exercise training interventions, however, much less is known with respect to peripheral MU properties. We therefore investigated whether targeted force accuracy training could lead to improved muscle functional capacity and control, in addition to determining any alterations of individual MU features. Methods Ten healthy participants (7 females, 3 males, 27±6 years, 170±8 cm, 69±16kg) underwent a 4-week supervised, unilateral knee extensor force accuracy training intervention. The coefficient of variation for force (FORCECoV ) and sinusoidal wave force tracking accuracy (FORCESinu ) were determined at 25% maximal voluntary contraction (MVC) pre- and post-training. Intramuscular electromyography was utilised to record individual MU potentials from the vastus lateralis (VL) muscles at 25% MVC during sustained contractions, pre- and post-training. Results Knee extensor muscle strength remained unchanged following training, with no improvements in unilateral leg-balance. FORCECoV and FORCESinu significantly improved in only the trained knee extensors by ∼13% (p = 0.01) and ∼30% (p<0.0001) respectively. MU FR variability significantly reduced in the trained VL by ∼16% (n = 8; p = 0.001), with no further alterations to MU FR or neuromuscular junction transmission instability. Conclusion Our results suggest muscle force control and tracking accuracy is a trainable characteristic in the knee extensors, which is likely explained by the reduction in MU FR variability which was apparent in the trained limb only. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Isabel A Ely
- Centre of Metabolism, Ageing and Physiology, MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research, National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, School of Medicine, University of Nottingham, Derby, United Kingdom
| | - Eleanor J Jones
- Centre of Metabolism, Ageing and Physiology, MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research, National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, School of Medicine, University of Nottingham, Derby, United Kingdom
| | - Thomas B Inns
- Centre of Metabolism, Ageing and Physiology, MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research, National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, School of Medicine, University of Nottingham, Derby, United Kingdom
| | - Síobhra Dooley
- School of Agriculture, Food Science and Veterinary Medicine, University College Dublin, Dublin, Ireland
| | - Sarah B J Miller
- School of Agriculture, Food Science and Veterinary Medicine, University College Dublin, Dublin, Ireland
| | - Daniel W Stashuk
- Department of Systems Design Engineering, University of Waterloo, Canada
| | - Philip J Atherton
- Centre of Metabolism, Ageing and Physiology, MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research, National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, School of Medicine, University of Nottingham, Derby, United Kingdom
| | - Bethan E Phillips
- Centre of Metabolism, Ageing and Physiology, MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research, National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, School of Medicine, University of Nottingham, Derby, United Kingdom
| | - Mathew Piasecki
- Centre of Metabolism, Ageing and Physiology, MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research, National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, School of Medicine, University of Nottingham, Derby, United Kingdom
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Schilaty ND, Savoldi F, Nasr Z, Weinshenker BG. Neuromotor control associates with muscle weakness observed with McArdle sign of multiple sclerosis. Ann Clin Transl Neurol 2022; 9:515-528. [PMID: 35289110 PMCID: PMC8994990 DOI: 10.1002/acn3.51526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 01/20/2022] [Accepted: 02/05/2022] [Indexed: 11/07/2022] Open
Abstract
OBJECTIVE Multiple Sclerosis (MS) is often accompanied by myelopathy, which may be associated with progressive worsening. A specific finding of MS-associated myelopathy is McArdle sign, wherein neck flexion is associated with prominent increased limb weakness relative to that detected with neck extension. In this study, we characterized neuromotor control properties of finger extensors in association with the McArdle sign. METHODS A custom-built device was utilized to monitor torque production of the wrist extensors with simultaneous recording of surface electromyography of the extensor digitorum. The electromyography was decomposed and analyzed via both linear and nominal regressions. RESULTS Linear regressions demonstrated a strong difference between groups for MS from healthy controls and other myelopathies for motor unit action potential amplitude and average firing rate (p < 0.001). Further, linear regression demonstrated good correlations of neuromotor variables to mechanical torque output (0.24 ≤ R2 ≤ 0.76). Nominal regression distinguished MS from healthy controls with an AUC of 0.87, specificity of 0.97, and sensitivity of 0.64. Nominal regression of MS from other myelopathies demonstrated an AUC of 0.88, specificity of 0.85, and sensitivity of 0.79. INTERPRETATION These data demonstrate the neuromotor control factors that largely determine muscle force production change with the observation of McArdle sign; these neuromotor control factors can differentiate MS from both healthy controls and other myelopathy conditions.
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Affiliation(s)
- Nathan D Schilaty
- Department of Neurosurgery & Brain Repair, University of South Florida, Tampa, Florida, USA.,Center for Neuromusculoskeletal Research, University of South Florida, Tampa, Florida, USA
| | - Filippo Savoldi
- Department of Neurology, Mayo Clinic, Rochester, Minnesota, USA
| | - Zahra Nasr
- Department of Neurology, Mayo Clinic, Rochester, Minnesota, USA
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Škarabot J, Brownstein CG, Casolo A, Del Vecchio A, Ansdell P. The knowns and unknowns of neural adaptations to resistance training. Eur J Appl Physiol 2020; 121:675-685. [PMID: 33355714 PMCID: PMC7892509 DOI: 10.1007/s00421-020-04567-3] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 11/18/2020] [Indexed: 12/22/2022]
Abstract
The initial increases in force production with resistance training are thought to be primarily underpinned by neural adaptations. This notion is firmly supported by evidence displaying motor unit adaptations following resistance training; however, the precise locus of neural adaptation remains elusive. The purpose of this review is to clarify and critically discuss the literature concerning the site(s) of putative neural adaptations to short-term resistance training. The proliferation of studies employing non-invasive stimulation techniques to investigate evoked responses have yielded variable results, but generally support the notion that resistance training alters intracortical inhibition. Nevertheless, methodological inconsistencies and the limitations of techniques, e.g. limited relation to behavioural outcomes and the inability to measure volitional muscle activity, preclude firm conclusions. Much of the literature has focused on the corticospinal tract; however, preliminary research in non-human primates suggests reticulospinal tract is a potential substrate for neural adaptations to resistance training, though human data is lacking due to methodological constraints. Recent advances in technology have provided substantial evidence of adaptations within a large motor unit population following resistance training. However, their activity represents the transformation of afferent and efferent inputs, making it challenging to establish the source of adaptation. Whilst much has been learned about the nature of neural adaptations to resistance training, the puzzle remains to be solved. Additional analyses of motoneuron firing during different training regimes or coupling with other methodologies (e.g., electroencephalography) may facilitate the estimation of the site(s) of neural adaptations to resistance training in the future.
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Affiliation(s)
- Jakob Škarabot
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK
| | - Callum G Brownstein
- Laboratoire Interuniversitaire de Biologie de la Motricité, Université Jean Monnet Saint-Etienne, Université Lyon, Saint-Étienne, France
| | - Andrea Casolo
- Department of Bioengineering, Imperial College London, London, UK.,Department of Biomedical Sciences, University of Padova, Padua, Italy
| | - Alessandro Del Vecchio
- Department of Artificial Intelligence and Biomedical Engineering, Faculty of Engineering, Friedrich-Alexander University, Erlangen-Nurnberg, 91052, Erlangen, Germany
| | - Paul Ansdell
- Department of Sport, Exercise and Rehabilitation, Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, NE1 8ST, UK.
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