Vincent Chen, B.S.
The leaner you are, the easier to keep lean! A recent study in our lab (Human Countermeasures Laboratory, Texas A&M University) revealed that participants with less percent body fat increased more fat-burning protein, PPAR-delta, after performing just a single bout of whole body resistance exercise. Furthermore, no matter how much your percent body fat is, PPAR-delta content increases after 10 weeks of resistance exercise training. PPAR-delta encourages skeletal muscle to burn stored fat as fuel. It can be greatly beneficial to health because it decreases triglyceride (a form of fat) and LDL-cholesterol (bad cholesterol) levels and increases insulin sensitivity and HDL-cholesterol (good cholesterol) levels. Since exercise is associated with energy expenditure and PPAR-delta is related to energy production, it is no surprise that our body can naturally produce more PPAR-delta in skeletal muscle simply by doing exercise.
It has been well established that endurance exercise, such as running, may increase PPAR-delta content. During the recent decade, researchers started to focus on the effects of resistance exercise on aerobic capacity and notice that PPAR-delta may play an important role in the regulation of energy expenditure of resistance exercise. In our labs, we have revealed that resistance exercise training may increase PPAR-delta contents in rats. Our recent study further investigates the effects of resistance exercise on PPAR-delta in humans.
Fifteen untrained men and women were recruited to perform a 10-week progressive whole body resistance exercise training program. Twenty-four hours before and after the first exercise, and 24 hours after the last exercise, we obtained muscle samples from their leg thigh. We were then able to compare the PPAR-delta content on different stage of the exercise.
By comparing the amount of PPAR-delta content in the muscle sample obtained 24 hours before and after the first exercise, we were able to identify the acute effect of resistance exercise on PPAR-delta. In this analysis, we found that PPAR-delta content increased in inverse proportion to participants' percent body fat. That is, participants with less percent body fat showed more increases in PPAR-delta content after performing only one bout of resistance exercise. This is an interesting finding because it shows that the leaner you are, the more fat your body tends to burn.
By comparing the amount of PPAR-delta content before and after the training program, we were able to evaluate the training effect of resistance exercise on PPAR-delta. Our results showed that PPAR-delta content increased after 10 weeks of resistance exercise training. This results tells us that resistance exercise training may increase your body's ability to use fat as energy source, just like endurance training. There are more factors, such as PGC-1 alpha and AMPK, the other main players of fat oxidation, that may affect and be affected by both resistance exercise and PPAR-delta. In order to reveal the relationship between these important factors and understand how resistance exercise affects fat metabolism, analyzing the change of PGC-1 alpha and AMPK contents with resistance exercise needs to be conducted.
- Barish, G. D., Narkar, V. A., & Evans, R. M. (2006). PPARδ: a dagger in the heart of the metabolic syndrome. The Journal of Clinical Investigation , 116, 590-597.
- Brunmair, B., Brunmair, K., Dörig, J., Szöcs, Z., Stadlbauer, K., Marian, V., et al. (2006). Activation of PPAR-δ in isolated rat skeletal muscle switches fuel preference from glucose to fatty acids.Diabetologia , 49, 2713–2722.