Heat stress enhances mTOR signaling after resistance exercise in human skeletal muscle.
Level 2 - randomized trial
Individual randomized crossover trial
PubMed 21222186 · doi:10.1007/s12576-010-0130-y
What was done
Eight young male participants performed four sets of six maximal knee extension repetitions with or without local heat stress in a randomized crossover design. Heat stress was applied to the vastus lateralis muscle belly using a microwave therapy unit before and during exercise. Muscle biopsies were collected from the vastus lateralis before, immediately after, and 1 hour post-exercise to measure mTOR signaling pathway phosphorylation.
What was found
No absolute numerical values or effect sizes are provided in the abstract. Compared with exercise alone, heat stress significantly increased phosphorylation of Akt/PKB, mTOR, and ribosomal protein S6 at 1 hour post-exercise (P < 0.05). Phosphorylation of ribosomal S6 kinase 1 was significantly elevated immediately after exercise with heat stress (P < 0.05). Phosphorylation of 4E-BP1, which decreased initially with exercise, recovered to baseline by 1 hour post-exercise in the heat stress condition.
Why it matters
This study demonstrates that applying local thermal stress during resistance exercise augments acute anabolic molecular signaling in human muscle.
Limits
The study is limited by a very small sample size (n = 8) consisting exclusively of young males. Only acute molecular markers up to 1 hour post-exercise were assessed; muscle protein synthesis rates, chronic training adaptations, and functional hypertrophy were not measured. Absolute values and confidence intervals are not reported in the abstract.
Cited by
- supports In a preliminary small study, sauna use following resistance training increased mTOR signaling molecules involved in muscle hypertrophy.