Cocoa supplementation inhibits mitochondrial adaptations in muscle produced by strenuous exercise

Abstract

INTRODUCCIÓN An increasing number of people who are not physically prepared often engage in strenuous exercise competitions (marathons, “quebrantahuesos”, desert runs, etc.). Strenuous exercise has negative health consequences, increasing the risk of cardiovascular disease and gastrointestinal problems [1,2]. Cocoa is used as a supplement during exercise, as it improves cardiovascular function and counteracts the associated exercise oxidative stress [3]. In addition, one of its components, epicatechin, has been shown to improve exercise adaptations, increasing mitochondrial biogenesis in both exercise and non-exercise animals [4,5]. The hypothesis of our study is that cocoa intake could increase exercise adaptations at the mitochondrial level. OBJETIVOS The purpose of this study was to determine whether cocoa supplementation prior to strenuous exercise improves exercise adaptations in an untrained mouse model to ultimately mitigate the negative effects of strenuous exercise. MÉTODOS Three groups of mice (n=10 per group) did not perform exercise and were fed for 4 weeks with: control diet, control diet supplemented with 8.2 g/kg cocoa and control diet supplemented with 24.6 g/kg cocoa. The cocoa doses were equivalent to the consumption of 5 g and 15 g cocoa per day for a 70 kg person. Three other groups were fed with the same three diets and underwent three sessions of intensive exercise. The mitochondrial DNA copy number was studied by qPCR quantifying the copy number of the mitochondrial ND1 and CYTB genes and the 18S nuclear gene in the quadriceps muscle. The results were analyzed by ANOVA with Bonferroni correction. RESULTADOS Our results show that cocoa supplementation did not increase mitochondrial biogenesis (number of copies of mitochondrial DNA), at any of the tested dose in animals that did not exercise, indicating that prior cocoa supplementation does not predispose the muscle to exercise. Strenuous exercise significantly increased the number of copies of mitochondrial DNA in the muscle. However, contrary to expectations, cocoa did not enhance exercise adaptations during exercise, but inhibited, at both doses, the mitochondrial biogenesis associated with exercise. CONCLUSIONES The mitochondrial biogenesis is a complex process regulated by reactive oxygen species (ROS). It is possible that cocoa, due to its antioxidant capacity, is inhibiting the production of ROS and therefore mitochondrial biogenesis [6].