Key result
Hyperthyroidism increases type IIA MHC muscle fibers linked to greater maximal shortening velocity.
Population
Soleus muscle fibers
Design
Preclinical
Authors
Loading...
Hyperthyroidism may alter skeletal muscle velocity via type IIA MHC fiber shifts in animal models; leaves open translation to human cardiac or skeletal performance.
The maximal shortening velocity of whole skeletal muscle may be determined by the relative proportion of fibers expressing fast type IIA MHC rather than solely by its fastest fibers.
Caiozzo et al. (1993) studied Hypo- and hyperthyroidism. Triiodothyronine treatment (hyperthyroidism) vs. Hypothyroidism was evaluated on Distribution of type IIA myosin heavy chain (MHC) and maximal shortening velocity. Hyperthyroidism significantly increased the relative number of muscle fibers expressing type IIA MHC, which highly correlated with maximal shortening velocity.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: