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Tavoian D, Clark BC, Clark LA, Wages NP, Russ DW. Comparison of strategies for assessment of rate of torque development in older and younger adults. Eur J Appl Physiol 2024; 124:551-560. [PMID: 37624389 DOI: 10.1007/s00421-023-05299-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2023] [Accepted: 08/11/2023] [Indexed: 08/26/2023]
Abstract
There is increasing appreciation of the role of rate of torque development (RTD) in physical function of older adults (OAs). This study compared various RTD strategies and electromyography (EMG) in the knee extensors and focused on discriminating groups with potential limitations in voluntary activation (VA) and associations of different RTD indices with functional tests that may be affected by VA in OAs. Neuromuscular function was assessed in 20 younger adults (YAs, 22.0 ± 1.7 years) and 50 OAs (74.4 ± 7.0 years). Isometric ballistic and peak torque during maximal voluntary contractions (pkTMVC), doublet stimulation and surface EMG were assessed and used to calculate VA during pkTMVC and RTD and rate of EMG rise during ballistic contractions. Select mobility tests (e.g., gait speed, 5× chair rise) were also assessed in the OAs. Voluntary RTD and RTD normalized to pkTMVC, doublet torque, and peak doublet RTD were compared. Rate of EMG rise and voluntary RTD normalized to pkTMVC did not differ between OAs and YAs, nor were they associated with functional test scores. Voluntary RTD indices normalized to stimulated torque parameters were significantly associated with VA (r = 0.319-0.459), and both indices were significantly lower in OAs vs YAs (all p < 0.020). These RTD indices showed significant association with the majority of mobility tests, but there was no clear advantage among them. Thus, voluntary RTD normalized to pkTMVC was ill-suited for use in OAs, while results suggests that voluntary RTD normalized to stimulated torque parameters may be useful for identifying central mechanisms of RTD impairment in OAs.Clinical trial registration number NCT02505529; date of registration 07/22/2015.
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Affiliation(s)
- Dallin Tavoian
- Ohio Musculoskeletal and Neurological Institute, Ohio University, Athens, OH, USA.
- University of Arizona, AHSC 4212, Tucson, AZ, 85724, USA.
| | - Brian C Clark
- Ohio Musculoskeletal and Neurological Institute, Ohio University, Athens, OH, USA
- Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, OH, USA
| | - Leatha A Clark
- Ohio Musculoskeletal and Neurological Institute, Ohio University, Athens, OH, USA
- Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, OH, USA
| | - Nathan P Wages
- Ohio Musculoskeletal and Neurological Institute, Ohio University, Athens, OH, USA
- Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, OH, USA
| | - David W Russ
- Ohio Musculoskeletal and Neurological Institute, Ohio University, Athens, OH, USA
- School of Physical Therapy and Rehabilitation Sciences, University of South Florida, Tampa, FL, USA
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Clark LA, Russ DW, Tavoian D, Arnold WD, Law TD, France CR, Clark BC. Heterogeneity of the strength response to progressive resistance exercise training in older adults: Contributions of muscle contractility. Exp Gerontol 2021; 152:111437. [PMID: 34098008 DOI: 10.1016/j.exger.2021.111437] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 05/13/2021] [Accepted: 06/01/2021] [Indexed: 01/23/2023]
Abstract
BACKGROUND Older adults display wide individual variability (heterogeneity) in the effects of resistance exercise training on muscle strength. The mechanisms driving this heterogeneity are poorly understood. Understanding of these mechanisms could permit development of more targeted interventions and/or improved identification of individuals likely to respond to resistance training interventions. Thus, this study assessed potential physiological factors that may contribute to strength response heterogeneity in older adults: neural activation, muscle hypertrophy, and muscle contractility. METHODS In 24 older adults (72.3 ± 6.8 years), we measured the following parameters before and after 12 weeks of progressive resistance exercise training: i) isometric leg extensor strength; ii) isokinetic (60°/sec) leg extensor strength; iii) voluntary (neural) activation by comparing voluntary and electrically-stimulated muscle forces (i.e., superimposed doublet technique); iv) muscle hypertrophy via dual-energy x-ray absorptiometry (DXA) estimates of regional lean tissue mass; and v) intrinsic contractility by electrically-elicited twitch and doublet torques. We examined associations between physiological factors (baseline values and relative change) and the relative change in isometric and isokinetic muscle strength. RESULTS Notably, changes in quadriceps contractility were positively associated with the relative improvement in isokinetic (r = 0.37-0.46, p ≤ 0.05), but not isometric strength (r = 0.09-0.21). Change in voluntary activation did not exhibit a significant association with the relative improvements in either isometric or isokinetic strength (r = 0.35 and 0.33, respectively; p > 0.05). Additionally, change in thigh lean mass was not significantly associated with relative improvement in isometric or isokinetic strength (r = 0.09 and -0.02, respectively; p > 0.05). Somewhat surprising was the lack of association between exercise-induced changes in isometric and isokinetic strength (r = 0.07). CONCLUSIONS The strength response to resistance exercise in older adults appears to be contraction-type dependent. Therefore, future investigations should consider obtaining multiple measures of muscle strength to ensure that strength adaptations are comprehensively assessed. Changes in lean mass did not explain the heterogeneity in strength response for either contraction type, and the data regarding the influence of voluntary activation was inconclusive. For isokinetic contraction, the strength response was moderately explained by between-subject variance in the resistance-exercise induced changes in muscle contractility.
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Affiliation(s)
- Leatha A Clark
- Ohio Musculoskeletal and Neurological Institute, Ohio University, Athens, OH, USA; Department of Biomedical Sciences, Ohio University, Athens, OH, USA.
| | - David W Russ
- School of Physical Therapy & Rehabilitation Sciences, University of South Florida, Tampa, FL, USA.
| | - Dallin Tavoian
- Ohio Musculoskeletal and Neurological Institute, Ohio University, Athens, OH, USA.
| | - W David Arnold
- Department of Neurology, The Ohio State University Wexner Medical Center, Columbus, OH, USA.
| | - Timothy D Law
- Ohio Musculoskeletal and Neurological Institute, Ohio University, Athens, OH, USA.
| | - Christopher R France
- Ohio Musculoskeletal and Neurological Institute, Ohio University, Athens, OH, USA; Department of Psychology, Ohio University, Athens, OH, USA.
| | - Brian C Clark
- Ohio Musculoskeletal and Neurological Institute, Ohio University, Athens, OH, USA; Department of Biomedical Sciences, Ohio University, Athens, OH, USA.
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Clark LA, Manini TM, Wages NP, Simon JE, Russ DW, Clark BC. Reduced Neural Excitability and Activation Contribute to Clinically Meaningful Weakness in Older Adults. J Gerontol A Biol Sci Med Sci 2021; 76:692-702. [PMID: 32588058 PMCID: PMC8011705 DOI: 10.1093/gerona/glaa157] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Weakness is a risk factor for physical limitations and death in older adults (OAs). We sought to determine whether OAs with clinically meaningful leg extensor weakness exhibit differences in voluntary inactivation (VIA) and measures of corticospinal excitability when compared to young adults (YAs) and OAs without clinically meaningful weakness. We also sought to estimate the relative contribution of indices of neural excitability and thigh lean mass in explaining the between-subject variability in OAs leg extensor strength. METHODS In 66 OAs (75.1 ± 7.0 years) and 20 YAs (22.0 ± 1.9 years), we quantified leg extensor strength, thigh lean mass, VIA, and motor evoked potential (MEP) amplitude and silent period (SP) duration. OAs were classified into weakness groups based on previously established strength/body weight (BW) cut points (Weak, Modestly Weak, or Not Weak). RESULTS The OAs had 63% less strength/BW when compared to YAs. Weak OAs exhibited higher levels of leg extensor VIA than Not Weak OAs (14.2 ± 7.5% vs 6.1 ± 7.5%). Weak OAs exhibited 24% longer SPs compared to Not Weak OAs, although this difference was insignificant (p = .06). The Weak OAs MEPs were half the amplitude of the Not Weak OAs. Regression analysis indicated that MEP amplitude, SP duration, and thigh lean mass explained ~62% of the variance in strength, with the neural excitability variables explaining ~33% of the variance and thigh lean mass explaining ~29%. CONCLUSION These findings suggest that neurotherapeutic interventions targeting excitability could be a viable approach to increase muscle strength in order to reduce the risk of physical impairments in late life.
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Affiliation(s)
- Leatha A Clark
- Ohio Musculoskeletal and Neurological Institute (OMNI), Ohio University, Athens
- Department of Biomedical Sciences, Ohio University, Athens
| | - Todd M Manini
- Department of Aging and Geriatric Research, University of Florida, Gainesville
| | - Nathan P Wages
- Ohio Musculoskeletal and Neurological Institute (OMNI), Ohio University, Athens
- Department of Biomedical Sciences, Ohio University, Athens
| | - Janet E Simon
- Ohio Musculoskeletal and Neurological Institute (OMNI), Ohio University, Athens
- School of Applied Health Sciences and Wellness, Ohio University, Athens
| | - David W Russ
- School of Physical Therapy & Rehabilitation Sciences, University of South Florida, Tampa
| | - Brian C Clark
- Ohio Musculoskeletal and Neurological Institute (OMNI), Ohio University, Athens
- Department of Biomedical Sciences, Ohio University, Athens
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Insights into the combination of neuromuscular electrical stimulation and motor imagery in a training-based approach. Eur J Appl Physiol 2021; 121:941-955. [PMID: 33417035 PMCID: PMC7892697 DOI: 10.1007/s00421-020-04582-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2020] [Accepted: 12/10/2020] [Indexed: 11/29/2022]
Abstract
Introduction Training stimuli that partially activate the neuromuscular system, such as motor imagery (MI) or neuromuscular electrical stimulation (NMES), have been previously shown as efficient tools to induce strength gains. Here the efficacy of MI, NMES or NMES + MI trainings has been compared. Methods Thirty-seven participants were enrolled in a training program of ten sessions in 2 weeks targeting plantar flexor muscles, distributed in four groups: MI, NMES, NMES + MI and control. Each group underwent forty contractions in each session, NMES + MI group doing 20 contractions of each modality. Before and after, the neuromuscular function was tested through the recording of maximal voluntary contraction (MVC), but also electrophysiological and mechanical responses associated with electrical nerve stimulation. Muscle architecture was assessed by ultrasonography. Results MVC increased by 11.3 ± 3.5% in NMES group, by 13.8 ± 5.6% in MI, while unchanged for NMES + MI and control. During MVC, a significant increase in V-wave without associated changes in superimposed H-reflex has been observed for NMES and MI, suggesting that neural adaptations occurred at supraspinal level. Rest spinal excitability was increased in the MI group while decreased in the NMES group. No change in muscle architecture (pennation angle, fascicle length) has been found in any group but muscular peak twitch and soleus maximal M-wave increased in the NMES group only. Conclusion Finally, MI and NMES seem to be efficient stimuli to improve strength, although both exhibited different and specific neural plasticity. On its side, NMES + MI combination did not provide the expected gains, suggesting that their effects are not simply cumulative, or even are competitive.
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Moskowitz S, Russ DW, Clark LA, Wages NP, Grooms DR, Woods AJ, Suhr J, Simon JE, O'Shea A, Criss CR, Fadda P, Clark BC. Is impaired dopaminergic function associated with mobility capacity in older adults? GeroScience 2020; 43:1383-1404. [PMID: 33236263 DOI: 10.1007/s11357-020-00303-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 11/18/2020] [Indexed: 01/14/2023] Open
Abstract
The capacity to move is essential for independence and declines with age. Slow movement speed, in particular, is strongly associated with negative health outcomes. Prior research on mobility (herein defined as movement slowness) and aging has largely focused on musculoskeletal mechanisms and processes. More recent work has provided growing evidence for a significant role of the nervous system in contributing to reduced mobility in older adults. In this article, we report four pieces of complementary evidence from behavioral, genetic, and neuroimaging experiments that, we believe, provide theoretical support for the assertion that the basal ganglia and its dopaminergic function are responsible, in part, for age-related reductions in mobility. We report four a posteriori findings from an existing dataset: (1) slower central activation of ballistic force development is associated with worse mobility among older adults; (2) older adults with the Val/Met intermediate catecholamine-O-methyl-transferase (COMT) genotype involved in dopamine degradation exhibit greater mobility than their homozygous counterparts; (3) there are moderate relationships between performance times from a series of lower and upper extremity tasks supporting the notion that movement speed in older adults is a trait-like attribute; and (4) there is a relationship of functional connectivity within the medial orbofrontal (mOFC) cortico-striatal network and measures of mobility, suggesting that a potential neural mechanism for impaired mobility with aging is the deterioration of the integrity of key regions within the mOFC cortico-striatal network. These findings align with recent basic and clinical science work suggesting that the basal ganglia and its dopaminergic function are mechanistically linked to age-related reductions in mobility capacity.
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Affiliation(s)
- Simon Moskowitz
- Ohio Musculoskeletal and Neurological Institute (OMNI), Ohio University, 250 Irvine Hall, Athens, OH, 45701, USA
| | - David W Russ
- Ohio Musculoskeletal and Neurological Institute (OMNI), Ohio University, 250 Irvine Hall, Athens, OH, 45701, USA.,School of Rehabilitation and Communication Sciences, Ohio University, Athens, OH, USA.,School of Physical Therapy & Rehabilitation Sciences, University of South Florida Morsani College of Medicine, Tampa, FL, USA
| | - Leatha A Clark
- Ohio Musculoskeletal and Neurological Institute (OMNI), Ohio University, 250 Irvine Hall, Athens, OH, 45701, USA.,Department of Biomedical Sciences at Ohio University, Athens, OH, USA.,Department of Family Medicine at Ohio University, Athens, OH, USA
| | - Nathan P Wages
- Ohio Musculoskeletal and Neurological Institute (OMNI), Ohio University, 250 Irvine Hall, Athens, OH, 45701, USA.,Department of Biomedical Sciences at Ohio University, Athens, OH, USA
| | - Dustin R Grooms
- Ohio Musculoskeletal and Neurological Institute (OMNI), Ohio University, 250 Irvine Hall, Athens, OH, 45701, USA.,School of Applied Health and Wellness, Ohio University, Athens, OH, USA
| | - Adam J Woods
- Center for Cognitive Aging and Memory, Department of Clinical and Health Psychology, University of Florida, Gainesville, FL, USA
| | - Julie Suhr
- Ohio Musculoskeletal and Neurological Institute (OMNI), Ohio University, 250 Irvine Hall, Athens, OH, 45701, USA.,Department of Psychology, Ohio University, Athens, OH, USA
| | - Janet E Simon
- Ohio Musculoskeletal and Neurological Institute (OMNI), Ohio University, 250 Irvine Hall, Athens, OH, 45701, USA.,School of Applied Health and Wellness, Ohio University, Athens, OH, USA
| | - Andrew O'Shea
- Center for Cognitive Aging and Memory, Department of Clinical and Health Psychology, University of Florida, Gainesville, FL, USA
| | - Cody R Criss
- Ohio Musculoskeletal and Neurological Institute (OMNI), Ohio University, 250 Irvine Hall, Athens, OH, 45701, USA
| | - Paolo Fadda
- Genomics Shared Resource-Comprehensive Cancer Center, The Ohio State University, Athens, OH, USA
| | - Brian C Clark
- Ohio Musculoskeletal and Neurological Institute (OMNI), Ohio University, 250 Irvine Hall, Athens, OH, 45701, USA. .,Department of Biomedical Sciences at Ohio University, Athens, OH, USA. .,Division of Geriatric Medicine at Ohio University, Athens, OH, USA.
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Oki K, Clark LA, Amano S, Clark BC. Effect of Anodal Transcranial Direct Current Stimulation of the Motor Cortex on Elbow Flexor Muscle Strength in the Very Old. J Geriatr Phys Ther 2020; 42:243-248. [PMID: 28906348 DOI: 10.1519/jpt.0000000000000145] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
BACKGROUND AND PURPOSE Muscle weakness predisposes older adults to a fourfold increase in functional limitations and has previously been associated with reduced motor cortex excitability in aging adults. The purpose of this study was to determine whether a single session of anodal transcranial direct current stimulation (tDCS) of the motor cortex would increase elbow flexion muscle strength and electromyographic (EMG) amplitude in very old individuals. METHODS Eleven very old individuals-85.8 (4.3) years-performed 3 maximal isometric elbow flexion contractions before and after 20 minutes of sham or anodal tDCS on different days. Order of stimulation was randomized, and the study participants and investigators were blinded to condition. In addition, voluntary activation capacity of the elbow flexors was determined by comparing voluntary and electrically evoked forces. RESULTS Anodal tDCS did not alter muscle strength or EMG activity in comparison to sham stimulation. Elbow flexion voluntary activation capacity was very high among the study participants: 99.3% (1.8%). CONCLUSION Contrary to our hypothesis, we observed no effect of anodal tDCS and no impairment in elbow flexor voluntary activation capacity in the very old. Whether anodal tDCS would exert a positive effect and support our initial hypothesis in another muscle group that does exhibit impairments in voluntary activation in older adults is a question that is still to be addressed.
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Affiliation(s)
- Kentaro Oki
- Ohio Musculoskeletal and Neurological Institute, Ohio University, Athens
| | - Leatha A Clark
- Ohio Musculoskeletal and Neurological Institute, Ohio University, Athens
| | - Shinichi Amano
- Ohio Musculoskeletal and Neurological Institute, Ohio University, Athens.,Clinical and Translational Research Unit, Ohio University, Athens
| | - Brian C Clark
- Ohio Musculoskeletal and Neurological Institute, Ohio University, Athens.,Department of Biomedical Sciences, Ohio University, Athens.,Department of Geriatric Medicine, Ohio University, Athens
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Enoka RM, Amiridis IG, Duchateau J. Electrical Stimulation of Muscle: Electrophysiology and Rehabilitation. Physiology (Bethesda) 2020; 35:40-56. [DOI: 10.1152/physiol.00015.2019] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The generation of action potentials in intramuscular motor and sensory axons in response to an imposed external current source can evoke muscle contractions and elicit widespread responses throughout the nervous system that impact sensorimotor function. The benefits experienced by individuals exposed to several weeks of treatment with electrical stimulation of muscle suggest that the underlying adaptations involve several physiological systems, but little is known about the specific changes elicited by such interventions.
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Affiliation(s)
- Roger M. Enoka
- Department of Integrative Physiology, University of Colorado Boulder, Colorado
| | - Ioannis G. Amiridis
- Department of Physical Education and Sport Sciences at Serres, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Jacques Duchateau
- Laboratory of Applied Biology and Neurophysiology, ULB Neuroscience Institute, Université Libre de Bruxelles, Brussels, Belgium
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Clark BC, Manini TM, Wages NP, Simon JE, Clark LA. Voluntary vs Electrically Stimulated Activation in Age-Related Muscle Weakness. JAMA Netw Open 2019; 2:e1912052. [PMID: 31553466 PMCID: PMC6763971 DOI: 10.1001/jamanetworkopen.2019.12052] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
This cross-sectional study compares voluntary neural activation of lower extremity muscles in clinically weak older adults vs stronger older adults.
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Affiliation(s)
- Brian C. Clark
- Ohio Musculoskeletal and Neurological Institute (OMNI), Ohio University, Athens
| | - Todd M. Manini
- Department of Aging and Geriatric Research, University of Florida, Gainesville
| | - Nathan P. Wages
- Ohio Musculoskeletal and Neurological Institute (OMNI), Ohio University, Athens
| | - Janet E. Simon
- Ohio Musculoskeletal and Neurological Institute (OMNI), Ohio University, Athens
| | - Leatha A. Clark
- Ohio Musculoskeletal and Neurological Institute (OMNI), Ohio University, Athens
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De Brandt J, Spruit MA, Derave W, Hansen D, Vanfleteren LEGW, Burtin C. Changes in structural and metabolic muscle characteristics following exercise-based interventions in patients with COPD: a systematic review. Expert Rev Respir Med 2016; 10:521-45. [PMID: 26901573 DOI: 10.1586/17476348.2016.1157472] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Patients with COPD suffer from lower-limb muscle dysfunction characterized by lower muscle oxidative capacity and muscle mass. Exercise-based training is expected to attenuate lower-limb intramuscular characteristics, but a detailed systematic approach to review the available evidence has not been performed yet. PUBMED and PEDro databases were searched. Twenty-five studies that implemented an exercise-based training program (aerobic and/or resistance training, high intensity interval training, electrical or magnetic stimulation) and reported muscle biopsy data of patients with COPD were critically appraised. The coverage of results includes changes in muscle structure, muscle protein turnover regulation, mitochondrial enzyme activity, oxidative and nitrosative stress, and inflammation after exercise-based training interventions. Study design and training modalities varied among studies, which partly explains the observed heterogeneous response in muscle characteristics. Gaps in the current knowledge are identified and recommendations for future research are made to enhance our knowledge on exercise training effects in patients with COPD.
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Affiliation(s)
- Jana De Brandt
- a REVAL - Rehabilitation Research Center, BIOMED - Biomedical Research Institute, Faculty of Medicine and Life Sciences , Hasselt University , Diepenbeek , Belgium
| | - Martijn A Spruit
- a REVAL - Rehabilitation Research Center, BIOMED - Biomedical Research Institute, Faculty of Medicine and Life Sciences , Hasselt University , Diepenbeek , Belgium.,b Department of Research and Education , CIRO, Center of Expertise for Chronic Organ Failure , Horn , The Netherlands
| | - Wim Derave
- c Department of Movement and Sports Sciences , Ghent University , Ghent , Belgium
| | - Dominique Hansen
- a REVAL - Rehabilitation Research Center, BIOMED - Biomedical Research Institute, Faculty of Medicine and Life Sciences , Hasselt University , Diepenbeek , Belgium
| | - Lowie E G W Vanfleteren
- b Department of Research and Education , CIRO, Center of Expertise for Chronic Organ Failure , Horn , The Netherlands
| | - Chris Burtin
- a REVAL - Rehabilitation Research Center, BIOMED - Biomedical Research Institute, Faculty of Medicine and Life Sciences , Hasselt University , Diepenbeek , Belgium
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