Heat treatment boosts anabolic effect of strength training

We’re not quite sure how strength athletes can apply the principle that Japanese sports scientists have written about in the Journal of Physiological Sciences. The equipment the scientists used to enhance post-strength training anabolic processes in muscles is not yet available. At least, not yet where ordinary mortals do their shopping. Or might infrared lamps be an alternative?

Anabolic heat
Heat treatment, or heat stress, has a mild anabolic effect. Strength training also has an anabolic effect. So do the two reinforce each other? The Japanese researchers set up an experiment to answer the question, using 8 young men with an average age of 22. The men were physically active but did not do weight training.

For the experiment the men trained their leg muscles using a leg-extension machine, doing four sets of six reps. The men rested for 2 minutes between sets. The researchers took small amounts of muscle cell out of the subjects’ leg muscles before, immediately after and 60 minutes after the mini-workout, and measured the activity of anabolic signal molecules in the cells.


On one occasion the men just did the leg training. [RE] On the other occasion the researchers placed a microwave therapy unit 15 cm above the subject’s leg. [HRE] They used the Microtizer MT-SDi made by Minato Medical. This was used to warm the subjects’ muscles, starting twenty minutes before the training session began and continued during the session. The muscle temperature was 8.9 degrees Celsius warmer than normal. The procedure is described in a letter published in the Journal of Sports Science and Medicine in 2008. [JSSM 2008 (7) 191-3.]

Training with heated muscles boosted the activity of Akt, mTOR, S6 and 4E-BP1 after the strength training.


The heat treatment had no effect on AMPK, S6K1, eEF2, ERK1/2 or p38.

The researchers speculate that the heat treatment activates the key anabolic regulator molecule Akt, which starts a cascade of reactions in the muscle cell.

“Although we expect that resistance exercise with heat stress will be a useful tool for maintaining and improving muscle mass, future studies should focus on the regulation of mTOR signaling molecules and the rate of protein synthesis in human skeletal muscle”, the Japanese conclude.

Heat stress enhances mTOR signaling after resistance exercise in human skeletal muscle.


This study investigated the effect of heat stress (HS) on mammalian target of rapamycin (mTOR) signaling involved in translation initiation after resistance exercise in human skeletal muscle. Eight young male subjects performed four sets of six maximal repetitions of knee extension exercises, with or without HS, in a randomized crossover design. HS was applied to the belly of the vastus lateralis by using a microwave therapy unit prior to and during exercise. Muscle biopsies were taken from the vastus lateralis before, immediately after, and 1 h after exercise. HS significantly increased the phosphorylation of Akt/PKB, mTOR, and ribosomal protein S6 at 1 h after exercise (P < 0.05), and the 4E-BP1 phosphorylation level, which had initially decreased with exercise, had recovered by 1 h after exercise with HS. In addition, the phosphorylation of ribosomal S6 kinase 1 was significantly increased immediately after exercise with HS (P < 0.05). These results indicate that HS enhances mTOR signaling after resistance exercise in human skeletal muscle. PMID: 21222186 [PubMed - indexed for MEDLINE] Source: http://www.ncbi.nlm.nih.gov/pubmed/21222186

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