Effect of heat stress on heat shock protein expression and hypertrophy-related signaling in the skeletal muscle of trained individuals.
Level 3 - non-randomized controlled study
Controlled human physiological study with in vitro laboratory experiment
PubMed 37842742 · doi:10.1152/ajpregu.00031.2023
What was done
Evaluated the impact of a single session of whole-body heat stress following resistance exercise (and heat stress alone) on heat shock protein (HSPA, HSPC) expression and Akt-mTOR signaling cascade activation in skeletal muscle of resistance-trained humans. Complementary in vitro experiments in murine C2C12 muscle cells assessed the effects of acute heat stress on myotube growth and myogenic fusion compared with growth factor stimulation.
What was found
Post-exercise whole-body heat stress increased skeletal muscle HSPA expression and Akt-mTOR cascade activation compared with resistance exercise alone in trained humans. Heat stress alone produced variable responses. In C2C12 cells, acute heat stress increased myotube growth and myogenic fusion, though less effectively than growth factors. The abstract reports no numerical values, effect sizes, or p-values.
Why it matters
The findings demonstrate that acute heat stress can potentiate molecular signaling pathways associated with muscle protein synthesis when applied after resistance exercise.
Limits
The abstract omits the human sample size, participant demographics beyond training status, specific heating parameters (modality, duration, temperature), and numerical data. The measurements are limited to acute molecular signaling markers rather than sustained muscle hypertrophy or functional strength changes.
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