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Nunes JP, Blazevich AJ, Schoenfeld BJ, Kassiano W, Costa BDV, Ribeiro AS, Nakamura M, Nosaka K, Cyrino ES. Determining Changes in Muscle Size and Architecture After Exercise Training: One Site Does Not Fit all. J Strength Cond Res 2024; 38:787-790. [PMID: 38513182 DOI: 10.1519/jsc.0000000000004722] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/23/2024]
Abstract
ABSTRACT Nunes, JP, Blazevich, AJ, Schoenfeld, BJ, Kassiano, W, Costa, BDV, Ribeiro, AS, Nakamura, M, Nosaka, K, and Cyrino, ES. Determining changes in muscle size and architecture after exercise training: One site does not fit all. J Strength Cond Res 38(4): 787-790, 2024-Different methods can be used to assess muscle hypertrophy, but the effects of training on regional changes in muscle size can be detected only using direct muscle measurements such as muscle thickness, cross-sectional area, or volume. Importantly, muscle size increases vary across regions within and between muscles after resistance training programs (i.e., heterogeneous, or nonuniform, muscle hypertrophy). Muscle architectural changes, including fascicle length and pennation angle, after resistance and stretch training programs are also region-specific. In this paper, we show that the literature indicates that a single-site measure of muscle shape does not properly capture the effects achieved after exercise training interventions and that conclusions concerning the magnitude of muscle adaptations can vary substantially depending on the muscle site to be examined. Thus, we propose that measurements of muscle size and architecture should be completed at multiple sites across regions between the agonist muscles within a muscle group and along the length of the muscles to provide an adequate picture of training effects.
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Affiliation(s)
- João Pedro Nunes
- Metabolism, Nutrition, and Exercise Laboratory, Physical Education and Sport Center, Londrina State University, Londrina, Brazil
- School of Medical and Health Sciences, Edith Cowan University, Joondalup, Australia
| | - Anthony J Blazevich
- School of Medical and Health Sciences, Edith Cowan University, Joondalup, Australia
| | | | - Witalo Kassiano
- Metabolism, Nutrition, and Exercise Laboratory, Physical Education and Sport Center, Londrina State University, Londrina, Brazil
| | - Bruna D V Costa
- Metabolism, Nutrition, and Exercise Laboratory, Physical Education and Sport Center, Londrina State University, Londrina, Brazil
| | - Alex S Ribeiro
- Metabolism, Nutrition, and Exercise Laboratory, Physical Education and Sport Center, Londrina State University, Londrina, Brazil
- Center for Research in Health Sciences, University of Northern Paraná, Londrina, Brazil; and
| | - Masatoshi Nakamura
- Faculty of Rehabilitation Sciences, Nishi Kyushu University, Saga, Japan
| | - Kazunori Nosaka
- School of Medical and Health Sciences, Edith Cowan University, Joondalup, Australia
| | - Edilson S Cyrino
- Metabolism, Nutrition, and Exercise Laboratory, Physical Education and Sport Center, Londrina State University, Londrina, Brazil
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Frouin A, Le Sant G, Barbier L, Jacquemin E, McNair PJ, Ellis R, Nordez A, Lacourpaille L. Individual distribution of muscle hypertrophy among hamstring muscle heads: Adding muscle volume where you need is not so simple. Scand J Med Sci Sports 2024; 34:e14608. [PMID: 38515303 DOI: 10.1111/sms.14608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 03/01/2024] [Accepted: 03/11/2024] [Indexed: 03/23/2024]
Abstract
PURPOSE The aim of this study was to determine whether a 9-week resistance training program based on high load (HL) versus low load combined with blood flow restriction (LL-BFR) induced a similar (i) distribution of muscle hypertrophy among hamstring heads (semimembranosus, SM; semitendinosus, ST; and biceps femoris long head, BF) and (ii) magnitude of tendon hypertrophy of ST, using a parallel randomized controlled trial. METHODS A total of 45 participants were randomly allocated to one of three groups: HL, LL-BFR, and control (CON). Both HL and LL-BFR performed a 9-week resistance training program composed of seated leg curl and stiff-leg deadlift exercises. Freehand 3D ultrasound was used to assess the changes in muscle and tendon volume. RESULTS The increase in ST volume was greater in HL (26.5 ± 25.5%) compared to CON (p = 0.004). No difference was found between CON and LL-BFR for the ST muscle volume (p = 0.627). The change in SM muscle volume was greater for LL-BFR (21.6 ± 27.8%) compared to CON (p = 0.025). No difference was found between HL and CON for the SM muscle volume (p = 0.178).There was no change in BF muscle volume in LL-BFR (14.0 ± 16.5%; p = 0.436) compared to CON group. No difference was found between HL and CON for the BF muscle volume (p = 1.0). Regarding ST tendon volume, we did not report an effect of training regimens (p = 0.411). CONCLUSION These results provide evidence that the HL program induced a selective hypertrophy of the ST while LL-BFR induced hypertrophy of SM. The magnitude of the selective hypertrophy observed within each group varied greatly between individuals. This finding suggests that it is very difficult to early determine the location of the hypertrophy among a muscle group.
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Affiliation(s)
- A Frouin
- Nantes Université, Movement - Interactions - Performance, MIP, Nantes, France
- Institut Sport Atlantique, ISA, Nantes, France
| | - G Le Sant
- Nantes Université, Movement - Interactions - Performance, MIP, Nantes, France
- School of Physiotherapy, IFM3R, Nantes, France
| | - L Barbier
- Nantes Université, Movement - Interactions - Performance, MIP, Nantes, France
- School of Physiotherapy, IFM3R, Nantes, France
| | - E Jacquemin
- Nantes Université, Movement - Interactions - Performance, MIP, Nantes, France
- School of Physiotherapy, IFM3R, Nantes, France
| | - P J McNair
- Health and Rehabilitation Research Institute, Faculty of Health and Environmental Sciences, Auckland University of Technology, Auckland, New Zealand
| | - R Ellis
- Health and Rehabilitation Research Institute, Faculty of Health and Environmental Sciences, Auckland University of Technology, Auckland, New Zealand
- Active Living and Rehabilitation: Aotearoa, School of Clinical Sciences, Auckland University of Technology, Auckland, New Zealand
| | - A Nordez
- Nantes Université, Movement - Interactions - Performance, MIP, Nantes, France
- Health and Rehabilitation Research Institute, Faculty of Health and Environmental Sciences, Auckland University of Technology, Auckland, New Zealand
- Institut Universitaire de France (IUF), Paris, France
| | - L Lacourpaille
- Nantes Université, Movement - Interactions - Performance, MIP, Nantes, France
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Weber KA, Teplin ZM, Wager TD, Law CSW, Prabhakar NK, Ashar YK, Gilam G, Banerjee S, Delp SL, Glover GH, Hastie TJ, Mackey S. Confounds in neuroimaging: A clear case of sex as a confound in brain-based prediction. Front Neurol 2022; 13:960760. [PMID: 36601297 PMCID: PMC9806266 DOI: 10.3389/fneur.2022.960760] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Accepted: 11/25/2022] [Indexed: 12/23/2022] Open
Abstract
Muscle weakness is common in many neurological, neuromuscular, and musculoskeletal conditions. Muscle size only partially explains muscle strength as adaptions within the nervous system also contribute to strength. Brain-based biomarkers of neuromuscular function could provide diagnostic, prognostic, and predictive value in treating these disorders. Therefore, we sought to characterize and quantify the brain's contribution to strength by developing multimodal MRI pipelines to predict grip strength. However, the prediction of strength was not straightforward, and we present a case of sex being a clear confound in brain decoding analyses. While each MRI modality-structural MRI (i.e., gray matter morphometry), diffusion MRI (i.e., white matter fractional anisotropy), resting state functional MRI (i.e., functional connectivity), and task-evoked functional MRI (i.e., left or right hand motor task activation)-and a multimodal prediction pipeline demonstrated significant predictive power for strength (R 2 = 0.108-0.536, p ≤ 0.001), after correcting for sex, the predictive power was substantially reduced (R 2 = -0.038-0.075). Next, we flipped the analysis and demonstrated that each MRI modality and a multimodal prediction pipeline could significantly predict sex (accuracy = 68.0%-93.3%, AUC = 0.780-0.982, p < 0.001). However, correcting the brain features for strength reduced the accuracy for predicting sex (accuracy = 57.3%-69.3%, AUC = 0.615-0.780). Here we demonstrate the effects of sex-correlated confounds in brain-based predictive models across multiple brain MRI modalities for both regression and classification models. We discuss implications of confounds in predictive modeling and the development of brain-based MRI biomarkers, as well as possible strategies to overcome these barriers.
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Affiliation(s)
- Kenneth A. Weber
- Systems Neuroscience and Pain Lab, Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, Palo Alto, CA, United States,*Correspondence: Kenneth A. Weber II
| | - Zachary M. Teplin
- Systems Neuroscience and Pain Lab, Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, Palo Alto, CA, United States
| | - Tor D. Wager
- Department of Psychological and Brain Sciences, Dartmouth College, Hanover, NH, United States
| | - Christine S. W. Law
- Systems Neuroscience and Pain Lab, Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, Palo Alto, CA, United States
| | - Nitin K. Prabhakar
- Division of Physical Medicine and Rehabilitation, Department of Orthopaedic Surgery, Stanford University School of Medicine, Palo Alto, CA, United States
| | - Yoni K. Ashar
- Department of Psychiatry, Weill Cornell Medicine, New York, NY, United States
| | - Gadi Gilam
- Systems Neuroscience and Pain Lab, Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, Palo Alto, CA, United States,The Institute of Biomedical and Oral Research, Faculty of Dental Medicine, Hebrew University of Jerusalem, Jerusalem, Israel
| | | | - Scott L. Delp
- Department of Bioengineering and Mechanical Engineering, Stanford University, Palo Alto, CA, United States
| | - Gary H. Glover
- Radiological Sciences Laboratory, Department of Radiology, Stanford University School of Medicine, Palo Alto, CA, United States
| | - Trevor J. Hastie
- Department of Statistics, Stanford University, Palo Alto, CA, United States
| | - Sean Mackey
- Systems Neuroscience and Pain Lab, Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, Palo Alto, CA, United States
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Van Every DW, Coleman M, Plotkin DL, Zambrano H, Van Hooren B, Larsen S, Nuckols G, Vigotsky AD, Schoenfeld BJ. Biomechanical, Anthropometric and Psychological Determinants of Barbell Bench Press Strength. Sports (Basel) 2022; 10:sports10120199. [PMID: 36548496 PMCID: PMC9785143 DOI: 10.3390/sports10120199] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 11/30/2022] [Accepted: 12/01/2022] [Indexed: 12/12/2022] Open
Abstract
The purpose of this study was to improve our understanding of the relative contributions of biomechanical, anthropometric, and psychological factors in explaining maximal bench press (BP) strength in a heterogeneous, resistance-trained sample. Eighteen college-aged participants reported to the laboratory for three visits. The first visit consisted of psychometric testing. The second visit assessed participants' anthropometrics, additional psychometric outcomes, and bench press one repetition maximum (1RM). Participants performed isometric dynamometry testing for horizontal shoulder adduction and elbow extension at a predicted sticking point joint position. Multiple linear regression was used to examine the relationships between the biomechanical, anthropometric, and psychological variables and BP 1RM. Our primary multiple linear regression accounted for 43% of the variance in BP strength (F(3,14) = 5.34, p = 0.01; R2 = 0.53; adjusted R2 = 0.43). The sum of peak isometric net joint moments from the shoulder and elbow had the greatest standardized effect (0.59), followed by lean body mass (0.27) and self-efficacy (0.17). The variance in BP 1RM can be similarly captured (R2 = 0.48) by a single principal component containing anthropometric, biomechanics, and psychological variables. Pearson correlations with BP strength were generally greater among anthropometric and biomechanical variables as compared to psychological variables. These data suggest that BP strength among a heterogeneous, resistance-trained population is explained by multiple factors and is more strongly associated with physical than psychological variables.
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Affiliation(s)
| | - Max Coleman
- Department of Health Sciences, CUNY Lehman College, New York, NY 10468, USA
| | - Daniel L. Plotkin
- Department of Health Sciences, CUNY Lehman College, New York, NY 10468, USA
| | - Hugo Zambrano
- Department of Health Sciences, CUNY Lehman College, New York, NY 10468, USA
| | - Bas Van Hooren
- Department of Nutrition and Movement Sciences, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, 6229 HX Maastricht, The Netherlands
| | - Stian Larsen
- Department of Sports Sciences and Physical Education, Nord University, 7600 Levanger, Norway
| | | | - Andrew D. Vigotsky
- Departments of Biomedical Engineering and Statistics, Northwestern University, Evanston, IL 60208, USA
| | - Brad J. Schoenfeld
- Department of Health Sciences, CUNY Lehman College, New York, NY 10468, USA
- Correspondence:
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Kojic F, Ranisavljev I, Obradovic M, Mandic D, Pelemis V, Paloc M, Duric S. Does Back Squat Exercise Lead to Regional Hypertrophy among Quadriceps Femoris Muscles? INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:16226. [PMID: 36498298 PMCID: PMC9737272 DOI: 10.3390/ijerph192316226] [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: 11/14/2022] [Revised: 11/30/2022] [Accepted: 12/01/2022] [Indexed: 06/17/2023]
Abstract
The present study investigated effects of squat resistance training on intermuscular hypertrophy of quadriceps femoris muscles (i.e., rectus femoris, RF; vastus intermedius, VI; vastus medialis, VM; and vastus lateralis, VL). Eighteen university students (age: 24.1 ± 1.7 years, 9 females) underwent 7 weeks of parallel squat training (2 days/week) preceded by a 2-week familiarization period. Squat strength (1RM) and cross-sectional area (CSA) of four quadriceps muscles were assessed at baseline and at the end of the study. At posttest, 1RM and CSA of quadriceps muscles significantly increased (p < 0.01), with moderate-to-large effect (ES = 1.25−2.11) for 1RM (8.33 ± 6.64 kg), VM CSA (0.12 ± 0.08 cm2), and VL CSA (0.19 ± 0.09 cm2) and small effect (ES = 0.89−1.13) for RF CSA (0.17 ± 0.15 cm2) and VI CSA (0.16 ± 0.18 cm2). No significant differences were found in the changes of CSA between muscles (F = 0.638, p = 0.593). However, the squat 1RM gain was significantly associated only with the changes in CSA of the VL muscle (r = 0.717, p < 0.001). The parallel squat resulted in significant growth of all quadriceps muscles. However, the novelty of this study is that the increase in strength is associated only with hypertrophy of the VL muscle.
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Affiliation(s)
- Filip Kojic
- Department for Physical Education, Teacher Education Faculty, University of Belgrade, 11000 Belgrade, Serbia
| | - Igor Ranisavljev
- Department for Strength and Conditioning Training, Faculty of Sport and Physical Education, University of Belgrade, 11000 Belgrade, Serbia
| | - Milos Obradovic
- Sports Center, Department for University Sport, University of Belgrade, 11000 Belgrade, Serbia
| | - Danimir Mandic
- Department for Physical Education, Teacher Education Faculty, University of Belgrade, 11000 Belgrade, Serbia
| | - Vladan Pelemis
- Department for Physical Education, Teacher Education Faculty, University of Belgrade, 11000 Belgrade, Serbia
| | - Milos Paloc
- Department for Strength and Conditioning Training, Faculty of Sport and Physical Education, University of Belgrade, 11000 Belgrade, Serbia
- Sports Center, Department for University Sport, University of Belgrade, 11000 Belgrade, Serbia
| | - Sasa Duric
- Liberal Arts Department, American University of the Middle East, Egaila 54200, Kuwait
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Kojić F, Arsenijević R, Ilić V, Đurić S. Relationship between hypertrophy, strength gains and tensiomyography adaptations: a moderator role of contraction duration. Eur J Appl Physiol 2022; 122:2223-2231. [PMID: 35831629 DOI: 10.1007/s00421-022-04998-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Accepted: 06/21/2022] [Indexed: 11/03/2022]
Abstract
The aim of the study was to investigate how the relationship between resistance training-induced hypertrophy, strength, and passive contractile adaptations is affected by contraction duration. Twenty university students (11 males) were randomly assigned to either the fast eccentric/fast concentric phase group (F/F; 1 s both phases) or the slow eccentric/fast concentric phase group (S/F; 4 s and 1 s, respectively). Both experimental groups completed a 7-week biceps curl training programme with a total of 14 sessions (2 days/week). Elbow flexor muscle thickness (MT), one-repetition maximum (1RM), and tensiomyographic (TMG) parameters (radial displacement-Dm and contraction time-Tc) were assessed. The percentage change (∆) in MT correlated significantly with the ∆1RM only in the S/F group (r = 0.712, p < 0.05). Both groups demonstrated significant negative associations between ∆MT and ∆Dm (r = 0.717-0.760, p < 0.01). Conversely, no significance was found between ∆MT and ∆Tc (F/F: r = -0.398, p = 0.255; S/F: r = 0.410, p = 0.239), ∆1RM and ∆Tc (F/F: r = -0.278, p = 0.436; S/F: r = 0.223, p = 0.536), nor ∆1RM and ∆Dm (F/F: r = - 0.131, p = 0.719; S/F: r = - 0.351, p = 0.320). The main findings indicate that the relationship between hypertrophy and strength gains is significantly stronger when resistance training was paced with slower eccentric contractions comparing to fast ones. On the other hand, reduced Dm values indicate increase in MT regardless of contraction duration, while strength gains are not correlated with corresponding TMG changes.
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Affiliation(s)
- Filip Kojić
- Teachers Education Faculty, University of Belgrade, Belgrade, Serbia
| | - Radenko Arsenijević
- Faculty of Sport and Physical Education, University of Prishtina, Leposavic, Serbia
| | - Vladimir Ilić
- Faculty of Sport and Physical Education, University of Belgrade, Belgrade, Serbia
| | - Saša Đurić
- Liberal Arts Department, General Education, American University of the Middle East, Al-Egaila, Block 3, Street No. 106, Kuwait City, Kuwait.
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Emery N, Strachan K, Kulshrestha R, Kuiper JH, Willis T. Evaluating the Feasibility and Reliability of Remotely Delivering and Scoring the North Star Ambulatory Assessment in Ambulant Patients with Duchenne Muscular Dystrophy. CHILDREN (BASEL, SWITZERLAND) 2022; 9:728. [PMID: 35626905 PMCID: PMC9139300 DOI: 10.3390/children9050728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 05/10/2022] [Accepted: 05/12/2022] [Indexed: 06/15/2023]
Abstract
OBJECTIVE The North Star Ambulatory Assessment (NSAA) is a validated 17-item functional rating scale and widely used to assess motor function in boys with Duchenne muscular dystrophy (DMD). The SARS-CoV-2 pandemic and subsequent Government 'lockdown' resulted in no face-to-face clinic visits hence the motor abilities were not monitored. The aim was to investigate whether the NSAA was feasible and reliable by video assessment. METHOD Ten ambulant DMD boys were selected from the electronic hospital records. Two physiotherapists scored the boys' NSAA independently and the intraclass correlation coefficient was used to assess agreement. The video scores were compared to two previous NSAA in-clinic scores. RESULTS Mean scores (SD) for clinic visit one were 22.6 (4.19) and clinic visit two 21.8 (5.3). The two physiotherapists video mean scores were 20.6 (5.66) for physiotherapist 1 and 20.6 (6.53) for physiotherapist 2. The intraclass correlation coefficient was 0.98 (95% CI 0.93-1.00) for the total NSAA and 1.00 (95% CI 1.00 to 1.00) for the rise time. The mean decline in score from clinic visit one (-12 months) to video assessment was 2.0 (2.8SD). CONCLUSION The results from the study suggest that video NSAA is partially feasible and reliable.
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Affiliation(s)
- Nicholas Emery
- Neuromuscular Service, TORCH Building, Robert Jones and Agnes Hunt Orthopaedic Hopsital, Shropshire SY10 7AG, UK; (N.E.); (K.S.); (J.H.K.); (T.W.)
| | - Kate Strachan
- Neuromuscular Service, TORCH Building, Robert Jones and Agnes Hunt Orthopaedic Hopsital, Shropshire SY10 7AG, UK; (N.E.); (K.S.); (J.H.K.); (T.W.)
| | - Richa Kulshrestha
- Neuromuscular Service, TORCH Building, Robert Jones and Agnes Hunt Orthopaedic Hopsital, Shropshire SY10 7AG, UK; (N.E.); (K.S.); (J.H.K.); (T.W.)
| | - Jan Herman Kuiper
- Neuromuscular Service, TORCH Building, Robert Jones and Agnes Hunt Orthopaedic Hopsital, Shropshire SY10 7AG, UK; (N.E.); (K.S.); (J.H.K.); (T.W.)
- School of Pharmacy and Bioengineering, Keele University, Staffordshire ST5 5BG, UK
| | - Tracey Willis
- Neuromuscular Service, TORCH Building, Robert Jones and Agnes Hunt Orthopaedic Hopsital, Shropshire SY10 7AG, UK; (N.E.); (K.S.); (J.H.K.); (T.W.)
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8
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Vigotsky AD, Halperin I, Trajano GS, Vieira TM. Longing for a Longitudinal Proxy: Acutely Measured Surface EMG Amplitude is not a Validated Predictor of Muscle Hypertrophy. Sports Med 2022; 52:193-199. [PMID: 35006527 DOI: 10.1007/s40279-021-01619-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/01/2021] [Indexed: 12/29/2022]
Abstract
Surface electromyography amplitudes are commonly measured in acute sports and exercise science studies to make inferences about muscular strength, performance, and hypertrophic adaptations that may result from different exercises or exercise-related variables. Here, we discuss the presumptive logic and assumptions underlying these inferences, focusing on hypertrophic adaptations for simplicity's sake. We present counter-evidence for each of its premises and discuss evidence both for and against the logical conclusion. Given the limited evidence validating the amplitude of surface electromyograms as a predictor of longitudinal hypertrophic adaptations, coupled with its weak mechanistic foundation, we suggest that acute comparative studies that wish to assess stimulus potency be met with scrutiny.
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Affiliation(s)
- Andrew D Vigotsky
- Departments of Biomedical Engineering and Statistics, Northwestern University, Evanston, IL, USA.
| | - Israel Halperin
- School of Public Health, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv-Yafo, Israel.,Sylvan Adams Sports Institute, Tel Aviv University, Tel Aviv-Yafo, Israel
| | - Gabriel S Trajano
- School of Exercise and Nutrition Sciences, Queensland University of Technology, Brisbane, QLD, Australia
| | - Taian M Vieira
- Laboratory for Engineering of the Neuromuscular System, Department of Electronics and Telecommunications, Politecnico di Torino, Turin, Italy
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9
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de Hoyo M, Núñez FJ, Sañudo B, Gonzalo-Skok O, Muñoz-López A, Romero-Boza S, Otero-Esquina C, Sánchez H, Nimphius S. Predicting Loading Intensity Measuring Velocity in Barbell Hip Thrust Exercise. J Strength Cond Res 2021; 35:2075-2081. [PMID: 31009439 DOI: 10.1519/jsc.0000000000003159] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
ABSTRACT de Hoyo, M, Núñez, FJ, Sañudo, B, Gonzalo-Skok, O, Muñoz-López, A, Romero-Boza, S, Otero-Esquina, C, Sánchez, H, and Nimphius, S. Predicting loading intensity measuring velocity in barbell hip thrust exercise. J Strength Cond Res 35(8): 2075-2081, 2021-The barbell hip thrust is an increasingly used exercise to target the hip extensors. Direct and indirect measurement of 1 repetition maximum (1RM) to determine the relative load of each exercise is time-consuming; therefore, practitioners may be more in favor of monitoring velocity and determining relative load through velocity-based prediction models for an exercise. This study aimed to assess the relationship between mean velocity (MV) and mean propulsive velocity (MPV) at different relative training loads (%1RM) in the barbell hip thrust exercise. One hundred two male sport science students performed an incremental 1RM testing protocol for the barbell hip thrust exercise, and a linear position transducer measured MV and MPV of the barbell. The 1RM was reached at 0.25 ± 0.03 m·s-1, and the regression model generated to estimate a relative load showed an acceptable standard error of estimate (7.01 ± 1.05% 1RM and 7.36 ± 1.05% 1RM for MV and MPV, respectively) with a very large explained variance (R2 = 0.94). These results may have important practical applications for the prescription and monitoring of the accessory exercise of the hip thrust for monitoring training load and predicting 1RM without undertaking a RM test.
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Affiliation(s)
- Moisés de Hoyo
- Department of Physical Education and Sport, University of Seville, Seville, Spain
| | - Francisco J Núñez
- Department of Sport and Computing, Faculty of Sport, Pablo de Olavide University, Seville, Spain
| | - Borja Sañudo
- Department of Physical Education and Sport, University of Seville, Seville, Spain
| | | | | | | | | | - Hugo Sánchez
- Fitness Section, Sevilla Football Club, Seville, Spain; and
| | - Sophia Nimphius
- Center for Exercise and Sports Science, School of Medical and Health Sciences, Edith Cowan University, Joondalup, Australia
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Ni Lochlainn M, Nessa A, Sheedy A, Horsfall R, García MP, Hart D, Akdag G, Yarand D, Wadge S, Baleanu AF, Whelan K, Steves C. The PROMOTe study: targeting the gut microbiome with prebiotics to overcome age-related anabolic resistance: protocol for a double-blinded, randomised, placebo-controlled trial. BMC Geriatr 2021; 21:407. [PMID: 34210274 PMCID: PMC8248289 DOI: 10.1186/s12877-021-02301-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 05/26/2021] [Indexed: 01/16/2023] Open
Abstract
BACKGROUND Loss of skeletal muscle mass and strength occurs with increasing age and is associated with loss of function, disability, and the development of sarcopenia and frailty. Dietary protein is essential for skeletal muscle function, but older adults do not anabolise muscle in response to protein supplementation as well as younger people, so called 'anabolic resistance'. The aetiology and molecular mechanisms for this are not understood, however the gut microbiome is known to play a key role in several of the proposed mechanisms. Thus, we hypothesise that the gut microbiome may mediate anabolic resistance and therefore represent an exciting new target for ameliorating muscle loss in older adults. This study aims to test whether modulation of the gut microbiome using a prebiotic, in addition to protein supplementation, can improve muscle strength (as measured by chair-rise time) versus protein supplementation alone. METHODS The study is a randomised, double-blinded, placebo-controlled trial, with two parallel arms; one will receive prebiotic and protein supplementation, and the other will receive placebo (maltodextrin) and protein supplementation. Participants will be randomised as twin pairs, with one twin from each pair in each arm. Participants will be asked to take supplementation once daily for 12 weeks in addition to resistance exercises. Every participant will receive a postal box, containing their supplements, and the necessary equipment to return faecal, urine, saliva and capillary blood samples, via post. A virtual visit will be performed using online platform at the beginning and end of the study, with measures taken over video. Questionnaires, food diary and cognitive testing will be sent out via email at the beginning and end of the study. DISCUSSION This study aims to provide evidence for the role of the gut microbiome in anabolic resistance to dietary protein. If those who take the prebiotic and protein supplementation have a greater improvement in muscle strength compared with those who take protein supplementation alone, this would suggest that strategies to modify the gut microbiome may reduce anabolic resistance, and therefore potentially mitigate sarcopenia and frailty in older adults. TRIAL REGISTRATION Clinicaltrials.gov: NCT04309292 . Registered on the 2nd May 2020.
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Affiliation(s)
- Mary Ni Lochlainn
- Department of Twin Research & Genetic Epidemiology, King's College London, 3rd Floor South Wing, St Thomas' Hospital, SE1 7EH, London, UK.
| | - Ayrun Nessa
- Department of Twin Research & Genetic Epidemiology, King's College London, 3rd Floor South Wing, St Thomas' Hospital, SE1 7EH, London, UK
| | - Alyce Sheedy
- Department of Twin Research & Genetic Epidemiology, King's College London, 3rd Floor South Wing, St Thomas' Hospital, SE1 7EH, London, UK
| | - Rachel Horsfall
- Department of Twin Research & Genetic Epidemiology, King's College London, 3rd Floor South Wing, St Thomas' Hospital, SE1 7EH, London, UK
| | - María Paz García
- Department of Twin Research & Genetic Epidemiology, King's College London, 3rd Floor South Wing, St Thomas' Hospital, SE1 7EH, London, UK
| | - Deborah Hart
- Department of Twin Research & Genetic Epidemiology, King's College London, 3rd Floor South Wing, St Thomas' Hospital, SE1 7EH, London, UK
| | - Gulsah Akdag
- Department of Twin Research & Genetic Epidemiology, King's College London, 3rd Floor South Wing, St Thomas' Hospital, SE1 7EH, London, UK
| | - Darioush Yarand
- Department of Twin Research & Genetic Epidemiology, King's College London, 3rd Floor South Wing, St Thomas' Hospital, SE1 7EH, London, UK
| | - Samuel Wadge
- Department of Twin Research & Genetic Epidemiology, King's College London, 3rd Floor South Wing, St Thomas' Hospital, SE1 7EH, London, UK
| | - Andrei-Florin Baleanu
- Department of Twin Research & Genetic Epidemiology, King's College London, 3rd Floor South Wing, St Thomas' Hospital, SE1 7EH, London, UK
| | - Kevin Whelan
- Department of Nutritional Sciences, King's College London, London, UK
| | - Claire Steves
- Department of Twin Research & Genetic Epidemiology, King's College London, 3rd Floor South Wing, St Thomas' Hospital, SE1 7EH, London, UK
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11
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Costa BDDV, Ferreira MEC, Gantois P, Kassiano W, Paes ST, de Lima-Júnior D, Cyrino ES, Fortes LDS. Acute Effect of Drop-Set, Traditional, and Pyramidal Systems in Resistance Training on Neuromuscular Performance in Trained Adults. J Strength Cond Res 2021; 35:991-996. [DOI: 10.1519/jsc.0000000000003150] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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12
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Vigotsky AD, Rouse EJ, Lee SSM. Mapping the relationships between joint stiffness, modeled muscle stiffness, and shear wave velocity. J Appl Physiol (1985) 2020; 129:483-491. [DOI: 10.1152/japplphysiol.00133.2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Shear wave velocity is commonly assessed to infer the muscular origins of changes in joint stiffness, but the exact relationship between shear wave velocity changes in muscle and joint stiffness changes remains unknown. Here, we systematically evaluated and quantified this relationship in the plantar flexors. Our results provide evidence for the ability of shear wave velocity to elucidate the muscular origins of joint stiffness changes.
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Affiliation(s)
- Andrew D. Vigotsky
- Departments of Biomedical Engineering and Statistics, Northwestern University, Evanston, Illinois
| | - Elliott J. Rouse
- Neurobionics Lab, Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan
| | - Sabrina S. M. Lee
- Department of Physical Therapy and Human Movement Sciences, Northwestern University, Chicago, Illinois
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13
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Orssatto LB, Bezerra ES, Shield AJ, Trajano GS. Is power training effective to produce muscle hypertrophy in older adults? A systematic review and meta-analysis. Appl Physiol Nutr Metab 2020; 45:1031-1040. [DOI: 10.1139/apnm-2020-0021] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Power training has been suggested to be effective in improving strength, power, and functional capacity in older adults. However, there is still a lack of systematic investigations reporting its effectiveness for muscle hypertrophy. Thus, this study investigated the effect of power training on muscle hypertrophy and compared its magnitude with traditional moderate-velocity resistance training in older adults. A systematic search was conducted to identify clinical trials investigating the effect of power training on muscle hypertrophy (power training vs. control) and/or comparing the effect of power training versus moderate-velocity resistance training for a meta-analytical approach. Ten studies comparing power training to control conditions and 9 studies comparing power training to moderate-velocity resistance training were selected. Three studies were classified as high quality and 2 were preregistered. The meta-analysis showed that power training was superior for muscle hypertrophy compared with control condition (n = 8 studies; standardised mean difference (SMD) = 0.31; 95% confidence interval (CI) = 0.04, 0.58; p = 0.029), and resulted in similar hypertrophy compared with moderate-velocity resistance training (n = 7 studies; SMD = 0.07; 95% CI = –0.18, 0.32; p = 0.50). No significant heterogeneity was observed (p = 0.46 and 0.54, and I2 = 0% and 0%, respectively). Our data suggest that power training is effective for muscle hypertrophy in older adults, with similar effectiveness as moderate-velocity resistance training. (PROSPERO registration no.: CRD42019128951.) Novelty It is known that power training might be superior to moderate-velocity resistance training for function improvements in older adults, but there was no meta-analysis investigating its effect on muscle hypertrophy. Power training is effective to induce muscle hypertrophy in older adults to a similar extent as moderate-velocity resistance training.
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Affiliation(s)
- Lucas B.R. Orssatto
- School of Exercise and Nutrition Sciences, Faculty of Health, Queensland University of Technology, Brisbane, QLD 4059, Australia
- Institute of Health and Biomedical Innovation, Faculty of Health, Queensland University of Technology, Brisbane, QLD 4059, Australia
| | - Ewertton S. Bezerra
- Laboratório de Estudo do Desempenho Humano, Faculdade de Educação Física e Fisioterapia, Universidade Federal do Amazonas, Manaus, AM 69067-005, Brazil
| | - Anthony J. Shield
- School of Exercise and Nutrition Sciences, Faculty of Health, Queensland University of Technology, Brisbane, QLD 4059, Australia
- Institute of Health and Biomedical Innovation, Faculty of Health, Queensland University of Technology, Brisbane, QLD 4059, Australia
| | - Gabriel S. Trajano
- School of Exercise and Nutrition Sciences, Faculty of Health, Queensland University of Technology, Brisbane, QLD 4059, Australia
- Institute of Health and Biomedical Innovation, Faculty of Health, Queensland University of Technology, Brisbane, QLD 4059, Australia
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14
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Loenneke JP, Buckner SL, Dankel SJ, Abe T. Exercise-Induced Changes in Muscle Size do not Contribute to Exercise-Induced Changes in Muscle Strength. Sports Med 2020; 49:987-991. [PMID: 31020548 DOI: 10.1007/s40279-019-01106-9] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Jeremy P Loenneke
- Department of Health, Exercise Science, and Recreation Management, Kevser Ermin Applied Physiology Laboratory, The University of Mississippi, P.O. Box 1848, University, MS, 38677, USA.
| | - Samuel L Buckner
- USF Muscle Lab, Exercise Science Program, University of South Florida, Tampa, FL, USA
| | - Scott J Dankel
- Department of Health, Exercise Science, and Recreation Management, Kevser Ermin Applied Physiology Laboratory, The University of Mississippi, P.O. Box 1848, University, MS, 38677, USA
| | - Takashi Abe
- Department of Health, Exercise Science, and Recreation Management, Kevser Ermin Applied Physiology Laboratory, The University of Mississippi, P.O. Box 1848, University, MS, 38677, USA
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15
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Exercise-Induced Myofibrillar Hypertrophy is a Contributory Cause of Gains in Muscle Strength. Sports Med 2020; 49:993-997. [PMID: 31016546 DOI: 10.1007/s40279-019-01107-8] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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16
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Does increasing an athletes’ strength improve sports performance? A critical review with suggestions to help answer this, and other, causal questions in sport science. ACTA ACUST UNITED AC 2020. [DOI: 10.17338/trainology.9.1_20] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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17
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Schoenfeld BJ, Grgic J, Contreras B, Delcastillo K, Alto A, Haun C, De Souza EO, Vigotsky AD. To Flex or Rest: Does Adding No-Load Isometric Actions to the Inter-Set Rest Period in Resistance Training Enhance Muscular Adaptations? A Randomized-Controlled Trial. Front Physiol 2020; 10:1571. [PMID: 32009980 PMCID: PMC6974452 DOI: 10.3389/fphys.2019.01571] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Accepted: 12/13/2019] [Indexed: 01/08/2023] Open
Abstract
We aimed to investigate the effects of resistance training (RT) combined with no-load isometric actions (iso-holds) during the inter-set recovery period versus RT that involves passive inter-set rest on muscular strength, muscular hypertrophy, and muscular endurance in resistance-trained men. Twenty-seven resistance-trained male volunteers were randomly assigned to either a traditional group (TRAD) that performed a hypertrophy-oriented RT routine with the rest intervals spent passively (n = 13) or to a group that supplemented traditional RT with iso-holds (ISO) for the working muscle group between each set (n = 14). Training for both routines consisted of three weekly sessions performed for 8 weeks. Three sets of 8–12 repetitions were performed per exercise. A 2-min rest interval was afforded between sets; the ISO group performed iso-holds for the first 30 s of each rest interval and then recovered for the final 90 s. Maximal strength was assessed using the one repetition maximum (1RM) tests in the leg press and bench press. Upper-body muscle endurance was assessed by performing the bench press to failure at 50% of 1RM. Muscle thickness (MT) of the elbow flexors, elbow extensors, mid-thigh, and lateral thigh was assessed using B-mode ultrasound. Results indicated a favorable effect of ISO on MT in the mid-thigh. Alternatively, there was a possible detrimental effect for ISO on leg press strength. No other notable differences were seen between conditions. In conclusion, the use of inter-set iso-holds may be a time-efficient strategy to enhance development of the quadriceps femoris; conversely, it may be detrimental to maximizing lower body strength.
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Affiliation(s)
- Brad J Schoenfeld
- Department of Health Sciences, CUNY Lehman College, New York City, NY, United States
| | - Jozo Grgic
- Institute for Health and Sport, Victoria University, Melbourne, VIC, Australia
| | - Bret Contreras
- Sport Performance Research Institute, Auckland University of Technology, Auckland, New Zealand
| | - Kenneth Delcastillo
- Department of Health Sciences, CUNY Lehman College, New York City, NY, United States
| | - Andrew Alto
- Department of Health Sciences, CUNY Lehman College, New York City, NY, United States
| | - Cody Haun
- Department of Exercise Science, LaGrange College, LaGrange, GA, United States
| | - Eduardo O De Souza
- Department of Health Sciences and Human Performance, The University of Tampa, Tampa, FL, United States
| | - Andrew D Vigotsky
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, United States.,Department of Statistics, Northwestern University, Evanston, IL, United States
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18
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Caldwell AR, Cheuvront SN. Basic statistical considerations for physiology: The journal Temperature toolbox. Temperature (Austin) 2019; 6:181-210. [PMID: 31608303 PMCID: PMC6773229 DOI: 10.1080/23328940.2019.1624131] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 05/19/2019] [Accepted: 05/21/2019] [Indexed: 12/26/2022] Open
Abstract
The average environmental and occupational physiologist may find statistics are difficult to interpret and use since their formal training in statistics is limited. Unfortunately, poor statistical practices can generate erroneous or at least misleading results and distorts the evidence in the scientific literature. These problems are exacerbated when statistics are used as thoughtless ritual that is performed after the data are collected. The situation is worsened when statistics are then treated as strict judgements about the data (i.e., significant versus non-significant) without a thought given to how these statistics were calculated or their practical meaning. We propose that researchers should consider statistics at every step of the research process whether that be the designing of experiments, collecting data, analysing the data or disseminating the results. When statistics are considered as an integral part of the research process, from start to finish, several problematic practices can be mitigated. Further, proper practices in disseminating the results of a study can greatly improve the quality of the literature. Within this review, we have included a number of reminders and statistical questions researchers should answer throughout the scientific process. Rather than treat statistics as a strict rule following procedure we hope that readers will use this review to stimulate a discussion around their current practices and attempt to improve them. The code to reproduce all analyses and figures within the manuscript can be found at https://doi.org/10.17605/OSF.IO/BQGDH.
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Affiliation(s)
- Aaron R. Caldwell
- Exercise Science Research Center, University of Arkansas–Fayetteville, Fayetteville, NC, USA
| | - Samuel N. Cheuvront
- Biophysics and Biomedical Modelling Division, US Army Research Institute of Environmental Medicine, Natick, MA, USA
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Pina FLC, Nunes JP, Nascimento MA, Ribeiro AS, Mayhew JL, Cyrino ES. Similar Effects of 24 Weeks of Resistance Training Performed with Different Frequencies on Muscle Strength, Muscle Mass, and Muscle Quality in Older Women. INTERNATIONAL JOURNAL OF EXERCISE SCIENCE 2019; 12:623-635. [PMID: 31156757 PMCID: PMC6533095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The purpose of this study was to analyze the effects of 24 weeks of resistance training (RT) performed 2 vs. 3 times per week on muscle strength, muscle mass, and muscle quality in older women. Thirty-nine older women (≥ 60 years old) were randomly assigned to two groups according to RT frequency (G2× = two sessions per week, n=19; and G3× = three sessions per week, n=20) and were submitted to 24 weeks of whole-body RT, divided into two stages of 12 weeks. In the first stage, participants performed 1 set of 10 to 15 repetitions in each of eight exercise, whereas in the second stage, they performed 2 sets of 10 to 15 repetitions. Muscle strength was assessed by one repetition maximum (1RM) tests in chest press, knee extension, and biceps preacher curl, while the lean soft tissue was estimated by DXA. The muscle quality index was determined by the ratio between strength and lean soft tissue. There were observed similar increases between groups for muscle strength (G2x=19.5%; G3×=22.2%), lean soft tissue (G2x=3.0%; G3×=1.6%), and muscle quality index (G2x=16.0%; G3×=21.1%). These results indicate that RT-induced muscular adaptation occurs regardless of training twice or thrice a week in older women. Instructors, coaches and practitioners can choose their training frequency preference, since both frequencies provided similar adaptations.
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Affiliation(s)
- Fábio L C Pina
- Center for Research in Health Sciences, University of Northern Paraná, Londrina, BRAZIL
| | - João Pedro Nunes
- Metabolism, Nutrition, and Exercise Laboratory, Physical Education and Sport Center, Londrina State University, Londrina, BRAZIL
| | - Matheus A Nascimento
- Metabolism, Nutrition, and Exercise Laboratory, Physical Education and Sport Center, Londrina State University, Londrina, BRAZIL
- Paraná State University - UNESPAR, Paranavaí campus, Paranavaí, BRAZIL
| | - Alex S Ribeiro
- Center for Research in Health Sciences, University of Northern Paraná, Londrina, BRAZIL
- Metabolism, Nutrition, and Exercise Laboratory, Physical Education and Sport Center, Londrina State University, Londrina, BRAZIL
| | - Jerry L Mayhew
- Exercise Science Program, Truman State University, Kirksville, Missouri, USA
| | - Edilson S Cyrino
- Metabolism, Nutrition, and Exercise Laboratory, Physical Education and Sport Center, Londrina State University, Londrina, BRAZIL
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Loenneke JP, Dankel SJ, Bell ZW, Buckner SL, Mattocks KT, Jessee MB, Abe T. Is muscle growth a mechanism for increasing strength? Med Hypotheses 2019; 125:51-56. [DOI: 10.1016/j.mehy.2019.02.030] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 02/07/2019] [Accepted: 02/09/2019] [Indexed: 11/24/2022]
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21
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Haun CT, Vann CG, Roberts BM, Vigotsky AD, Schoenfeld BJ, Roberts MD. A Critical Evaluation of the Biological Construct Skeletal Muscle Hypertrophy: Size Matters but So Does the Measurement. Front Physiol 2019; 10:247. [PMID: 30930796 PMCID: PMC6423469 DOI: 10.3389/fphys.2019.00247] [Citation(s) in RCA: 93] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Accepted: 02/25/2019] [Indexed: 12/11/2022] Open
Abstract
Skeletal muscle is highly adaptable and has consistently been shown to morphologically respond to exercise training. Skeletal muscle growth during periods of resistance training has traditionally been referred to as skeletal muscle hypertrophy, and this manifests as increases in muscle mass, muscle thickness, muscle area, muscle volume, and muscle fiber cross-sectional area (fCSA). Delicate electron microscopy and biochemical techniques have also been used to demonstrate that resistance exercise promotes ultrastructural adaptations within muscle fibers. Decades of research in this area of exercise physiology have promulgated a widespread hypothetical model of training-induced skeletal muscle hypertrophy; specifically, fCSA increases are accompanied by proportional increases in myofibrillar protein, leading to an expansion in the number of sarcomeres in parallel and/or an increase in myofibril number. However, there is ample evidence to suggest that myofibrillar protein concentration may be diluted through sarcoplasmic expansion as fCSA increases occur. Furthermore, and perhaps more problematic, are numerous investigations reporting that pre-to-post training change scores in macroscopic, microscopic, and molecular variables supporting this model are often poorly associated with one another. The current review first provides a brief description of skeletal muscle composition and structure. We then provide a historical overview of muscle hypertrophy assessment. Next, current-day methods commonly used to assess skeletal muscle hypertrophy at the biochemical, ultramicroscopic, microscopic, macroscopic, and whole-body levels in response to training are examined. Data from our laboratory, and others, demonstrating correlations (or the lack thereof) between these variables are also presented, and reasons for comparative discrepancies are discussed with particular attention directed to studies reporting ultrastructural and muscle protein concentration alterations. Finally, we critically evaluate the biological construct of skeletal muscle hypertrophy, propose potential operational definitions, and provide suggestions for consideration in hopes of guiding future research in this area.
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Affiliation(s)
- Cody T Haun
- Department of Exercise Science, LaGrange College, LaGrange, GA, United States
| | | | - Brandon M Roberts
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Andrew D Vigotsky
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, United States
| | - Brad J Schoenfeld
- Department of Health Sciences, CUNY Lehman College, Bronx, NY, United States
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