Effects of Polyphenols Supplementation on Cycling Endurance

Endurance performance during high intensive exercises is mainly determined by the capacity of the aerobic metabolism. It generally induces muscle fatigue defined as the reversible decline in skeletal muscle contractile performance. Fatigue is multifactorial and is often associated with many physiological parameters including reduced neural input and disruptive metabolic changes in skeletal muscles such as lactic acidosis and the production of oxidative free radicals. Moreover, it could lead to oxidative stress as a result of an imbalance between reactive oxygen species (ROS) production and intrinsic antioxidant defense.

To alleviate oxidative stress, some ergogenic strategies have been tested. Numerous studies have reported that different types of supplementation such as selenium, vitamin E, vitamin C or polyphenols were of interest to protect against these mechanisms. Indeed, although some studies demonstrated no or harmful effects, most studies observed positive effects of antioxidants on oxidative stress or performance. More particularly, polyphenols, have great antioxidant capabilities and protective effects and it increases the synthesis and bioavailability of nitric oxide (NO)which is well known to be the most important mediator of vasodilation. To date, most of the studies exploring the effects of polyphenols on exercise investigated several days or weeks of supplementations on vascular, blood parameters (blood pressure, NO concentration, oxidative stress markers) or endurance performance. Conflicting results are often obtained. Only few studies investigated the effects of a single intake on immediate performance and recovery capacity. Therefore, the present work aimed to study the effects of an acute intake of a specific profile polyphenols from grape and apple on physical performances. More specifically, performance, in the present study, referred to high intensity cycling exercise until exhaustion revealing the capacity to maintain a constant strong effort hereafter named endurance. The hypothesis was that an acute of polyphenols would increase the time to exhaustion during a high intensity cycling exercise.