Exercise-Induced Changes in Muscle Size do not Contribute to Exercise-Induced Changes in Muscle Strength

Loenneke, Jeremy P.; Buckner, Samuel L.; Dankel, Scott J.; Abe, Takashi

doi:10.1007/s40279-019-01106-9

Cited by 56 publications

(51 citation statements)

References 43 publications

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“…However, when examining correlations between exerciseinduced changes in muscle size and strength, these analyses are completed on groups designed to increase both muscle size and strength and also appear to be primarily correlating the error/random biological variability with muscle size with the error/random biological variability in muscle strength (Dankel et al, 2018). In other words, there is still no available evidence supporting the claim that changes in muscle size lead to changes in strength (Loenneke et al, 2019), and this aspect needs to be examined. Usui et al (2016) used an 8-week 50% 1RM squat training protocol at slow speed (3 s for concentric/eccentric actions) and found training-induced increase in strength of the HE but not of the KE.…”

Section: Discussionmentioning

confidence: 99%

Eight-Week Low-Intensity Squat Training at Slow Speed Simultaneously Improves Knee and Hip Flexion and Extension Strength

et al. 2020

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Considering that the squat exercise requires flexion and extension of the knee and hip joints, a resistance training program based on squat exercises should efficiently increase the flexion and extension strength of both the knee and hip. To our knowledge, however, no study has simultaneously investigated the effects of squat training on both flexion and extension strength in both the knee and hip. Low-intensity squat exercises at slow speeds can be expected to effectively and safely improve knee and hip flexion and extension strength in a wide range of individuals. This study aimed to clarify whether knee and hip flexion and extension strength improved after an 8-week low-intensity squat training program at slow speed. Twenty-four untrained young men were randomly assigned to a training or control group. Participants in the training group performed 40% one-repetition maximum parallel squats at slow speed (4 s for concentric/eccentric actions), 3 days per week for 8 weeks. Before and after the intervention, isometric peak torque of the knee and hip flexors and extensors during maximal voluntary contraction (MVC) was determined. For the knee flexors and extensors, muscle volume was also measured. There were significant training-induced increases in peak torque (P < 0.05). The training effects on knee and hip extension torque (effect size = 0.36-0.38) were higher than those on knee and hip flexion torque (effect size = 0.09-0.13). The squat training used here increased both knee and hip flexion and extension strength, but the training effects on the flexion strength were less than those on the extension strength. Regarding the knee extensors, a significant training-related increase in muscle volume was found (P < 0.05) without neuromuscular adaptations. In addition, there were significant correlations between the training-induced increases in muscle volume and peak torque of KE. These results suggest that muscle hypertrophy may be responsible for increased muscle strength of the knee extensors after an 8-week low-intensity squat training program at slow speed.

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Section: Discussionmentioning

confidence: 99%

Eight-Week Low-Intensity Squat Training at Slow Speed Simultaneously Improves Knee and Hip Flexion and Extension Strength

et al. 2020

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“…The total body and abdominal measurements are the basis of body composition assessments, which, often combined with nutritional aspects, are integrated into clinical routine and have been used for the diagnosis and monitoring of disease progression in oncology, diabetes, obesity, sarcopenia, and cardiovascular [186][187][188][189]. However, there is a disassociation between muscle strength or power and lean mass or muscle size with respect to exercise intervention and age-dependent changes, because the contractile muscle capacity is strongly influenced by the EMCL and IMCL distribution [190][191][192][193][194]. In consequence, a quantitative assessment of the muscle composition has been suggested [195].…”

Section: Voismentioning

confidence: 99%

Interactions between Muscle and Bone—Where Physics Meets Biology

et al. 2020

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Muscle and bone interact via physical forces and secreted osteokines and myokines. Physical forces are generated through gravity, locomotion, exercise, and external devices. Cells sense mechanical strain via adhesion molecules and translate it into biochemical responses, modulating the basic mechanisms of cellular biology such as lineage commitment, tissue formation, and maturation. This may result in the initiation of bone formation, muscle hypertrophy, and the enhanced production of extracellular matrix constituents, adhesion molecules, and cytoskeletal elements. Bone and muscle mass, resistance to strain, and the stiffness of matrix, cells, and tissues are enhanced, influencing fracture resistance and muscle power. This propagates a dynamic and continuous reciprocity of physicochemical interaction. Secreted growth and differentiation factors are important effectors of mutual interaction. The acute effects of exercise induce the secretion of exosomes with cargo molecules that are capable of mediating the endocrine effects between muscle, bone, and the organism. Long-term changes induce adaptations of the respective tissue secretome that maintain adequate homeostatic conditions. Lessons from unloading, microgravity, and disuse teach us that gratuitous tissue is removed or reorganized while immobility and inflammation trigger muscle and bone marrow fatty infiltration and propagate degenerative diseases such as sarcopenia and osteoporosis. Ongoing research will certainly find new therapeutic targets for prevention and treatment.

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“…We appreciate the opportunity to respond to Loenneke et al [44] and for these authors' willingness to exchange points on this matter. As we noted in our initial writing, evidence supports the contention that hypertrophy is neither a necessary nor sufficient cause of improved strength in all contexts.…”

Section: Reply To Loenneke Et Almentioning

confidence: 98%

Exercise-Induced Myofibrillar Hypertrophy is a Contributory Cause of Gains in Muscle Strength

et al. 2019

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Exercise-Induced Changes in Muscle Size do not Contribute to Exercise-Induced Changes in Muscle Strength

Cited by 56 publications

References 43 publications

Eight-Week Low-Intensity Squat Training at Slow Speed Simultaneously Improves Knee and Hip Flexion and Extension Strength

Eight-Week Low-Intensity Squat Training at Slow Speed Simultaneously Improves Knee and Hip Flexion and Extension Strength

Interactions between Muscle and Bone—Where Physics Meets Biology

Exercise-Induced Myofibrillar Hypertrophy is a Contributory Cause of Gains in Muscle Strength

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