Effect of Capsinoids Supplementation on Fat Oxidation and Muscle Glycogen Restoration During Post-exercise Recovery in Humans.

BACKGROUND: Capsinoids (CSN), the novel non-pungent capsaicin analogs have been reported to promote metabolic health and exercise tolerance. However, the effect of CSN on fat oxidation and changes in skeletal muscle glycogen levels during post-exercise recovery has not been investigated in humans. <P> Purpose: We examined the effect of CSN supplementation on energy reliance, glycogen resynthesis and molecular proteins in the skeletal muscle of young adults during post-exercise recovery. <P> Methods: In this crossover-designed study, nine healthy adult male volunteers (aged 21.4±0.2 years, BMI 21.9±1.3 kg/m2 ) completed a 60-min cycling exercise at 70% VO2max. Participants consumed either CSN (12 mg, single dosage) or placebo capsules with a high-carbohydrate meal (2 g carb/kg bodyweight) immediately after exercise. Biopsied muscle samples (vastus lateralis), blood and gaseous samples were obtained during 3h post-exercise recovery period. <P> Results: We found that oral CSN supplementation right after exercise significantly altered the energy reliance on fat oxidation during recovery. This was evidenced by lower respiratory exchange ratio (RER) and higher fat oxidation rate in CSN trial. Despite, acute CSN dosage does not contribute to enhance the glycogen replenishment in skeletal muscle during 3h recovery. We identified no significant differences in postprandial glucose and insulin area under the curve in both trials. Western blot data showed increased muscle GLUT4 expression, but no significant response of p-Akt/Akt ratio with CSN during post-exercise recovery. <P> Conclusion: Our findings conclude that acute CSN intake could change energy reliance on fat oxidation, but unable to enhance muscle glycogen resynthesis during post-exercise recovery. Thus, ergogenic properties of CSN in relevance to muscle glycogen restoration following exercise needs to be further investigated in young adults.