Research
Hormonal
Thyroid hormone (T3) accelerates skeletal muscle contraction and relaxation rates by stimulating the expression of fast myosin heavy chain isoforms (MYH2, MYH1, MYH4) and sarcoplasmic reticulum Ca2+ ATPase (SERCA1a).
If you have hypothyroidism, treating it to normal levels may help restore normal muscle speed and function, as thyroid hormone directly controls the proteins responsible for contraction speed. However, for healthy individuals, manipulating thyroid levels is not a standard or safe performance enhancement strategy.
GoodSupportsHIGH confidence
TH induces the fibre type switch to a faster profile of the contraction–relaxation cycle. THs repress slow type I fibre MYH7 expression and stimulate the rapid type II fibres’ MYH-2, -1, and -4 expression. TH-induced expression of SERCA 1a and 2a increases relaxation.
Why this rating
Supported by multiple animal models (MCT8KO, ThraKO) and human biopsy data, though mostly observational/mechanistic.
Source
Role of thyroid hormone in skeletal muscle physiology
Flávia Fonseca Bloise et al. · Journal of Endocrinology · 2017
DOI 10.1530/joe-16-0611
narrative_reviewCited 231×
Read the paper DOI resolved against Crossref · corpus check 2026-06-10
More from this paper
- Thyroid hormone (T3) increases skeletal muscle mitochondrial biogenesis, oxidative capacity, and resting metabolic rate by upregulating PGC1α, UCP3, and mitochondrial enzymes.Good
- Thyroid hormone (T3) regulates skeletal muscle myogenesis by controlling intracellular T3 levels via D2 and D3 deiodinases, which determines satellite cell proliferation and differentiation.Good
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