Effect of pre-exercise nutrition on human skeletal muscle UCP-3 expression.

Uncoupling proteins have been proposed as potential therapeutic target for treating obesity and its related diseases such as type II diabetes mellitus. Free fatty acids (FFA) have been shown to be a possible regulator of UCP-3 expression in skeletal muscle, however, studies have shown conflicting results. Using a crossover design, untrained participants performed an endurance exercise session (350 kcal working at 70% of their VO2peak) after two experimental conditions, after the consumption of a multi-macronutrient shake or after a fasting period of 8 h. Results show a significant increase in FFA in the fasting condition as well as a significant increase in UCP-3 mRNA and protein expression at 1 h and 4 h respectively in the shake condition. It is concluded that UCP-3 mRNA and protein expression might be controlled in a stronger way by factors other than FFA. Variables like the protein and fat content from the multi-macronutrient shake, as well as the insulin levels in the shake condition, could have played a key role in the significant increase in UCP-3 mRNA and protein expression in the shake condition; however, further research is needed to confirm this hypothesis.