Cited by 1,347Sports Performance and TrainingMuscle Physiology and DisordersMuscle activation and electromyography studies

The Adaptations to Strength Training: Morphological and Neurological Contributions to Increased Strength

Folland, Jonathan P, Williams, Alun G·2007·Sports Medicine

Abstract

High-resistance strength training (HRST) is one of the most widely practiced forms of physical activity, which is used to enhance athletic performance, augment musculo-skeletal health and alter body aesthetics. Chronic exposure to this type of activity produces marked increases in muscular strength, which are attributed to a range of neurological and morphological adaptations. This review assesses the evidence for these adaptations, their interplay and contribution to enhanced strength and the methodologies employed. The primary morphological adaptations involve an increase in the cross-sectional area of the whole muscle and individual muscle fibres, which is due to an increase in myofibrillar size and number. Satellite cells are activated in the very early stages of training; their proliferation and later fusion with existing fibres appears to be intimately involved in the hypertrophy response. Other possible morphological adaptations include hyperplasia, changes in fibre type, muscle architecture, myofilament density and the structure of connective tissue and tendons. Indirect evidence for neurological adaptations, which encompasses learning and coordination, comes from the specificity of the training adaptation, transfer of unilateral training to the contralateral limb and imagined contractions. The apparent rise in whole-muscle specific tension has been primarily used as evidence for neurological adaptations; however, morphological factors (e.g. preferential hypertrophy of type 2 fibres, increased angle of fibre pennation, increase in radiological density) are also likely to contribute to this phenomenon. Changes in inter-muscular coordination appear critical. Adaptations in agonist muscle activation, as assessed by electromyography, tetanic stimulation and the twitch interpolation technique, suggest small, but significant increases. Enhanced firing frequency and spinal reflexes most likely explain this improvement, although there is contrary evidence suggesting no change in cortical or corticospinal excitability. The gains in strength with HRST are undoubtedly due to a wide combination of neurological and morphological factors. Whilst the neurological factors may make their greatest contribution during the early stages of a training programme, hypertrophic processes also commence at the onset of training.

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Crossref · 10.2165/00007256-200737020-00004

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Authors
Folland, J. P., & Williams, A. G.
Affiliations
  • Loughborough University (GB)
  • Manchester Metropolitan University (GB)
Corresponding author
Folland, Jonathan P
Venue
Sports Medicine
Published
2007
Volume
37
Issue
2
Pages
145-168
ISSN
0112-1642 (ISSN-L)
OpenAlex
W1978684156
Cited by
1,347
References
280
Citations by year
2026: 90 · 2025: 102 · 2024: 96 · 2023: 77 · 2022: 106 · 2021: 102 · 2020: 92 · 2019: 78 · 2018: 73 · 2017: 72 · 2016: 64 · 2015: 65 · 2014: 69 · 2013: 62 · 2012: 47
FWCI
5.91
Type
journal article
Language
en
Open access
closed
Locations
  • Sports Medicine (publishedVersion)
  • PubMed (publishedVersion)
  • e-space (Manchester Metropolitan University) (submittedVersion)
Topics
  • Health Sciences › Medicine › Orthopedics and Sports Medicine › Sports Performance and Training
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Muscle Physiology and Disorders
  • Physical Sciences › Engineering › Biomedical Engineering › Muscle activation and electromyography studies
Keywords
muscle strength, hypertrophy, satellite cells, muscle fiber type, muscle architecture, specific tension, motor unit activation, corticospinal excitability, spinal reflexes, training effects
MeSH terms
Adaptation, Physiological, Electromyography, Physical Exertion, Humans, Muscle Contraction, Myosins, Physical Endurance, Sports, Weight Lifting, Muscle, Skeletal

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