During intense Physical activity (PA), skeletal muscles become a major source of reactive oxygen species (ROS). Intense and prolonged exercise, as in high-level athletes, results in increased ROS mitochondrial formation, higher levels of inflammation, and oxidative damage, overwhelming the antioxidant defense ability. Antioxidant supplementation, such as cocoa flavanols (CF), is a potentially noninvasive strategy to scavenge additional ROS and reduce cardiovascular oxidative damage, preventing a decline in exercise performance and optimize post-exercise recovery. Aim of this proposal is to investigate the effects of CF dietary implementation as a mechanism to counteract ROS production during exercise by a comprehensive multifaceted approach, thru the evaluation of the acute and chronic effects of CF dietary implementation on physical performance and cardiovascular parameters in elite athletes, and putative molecular mechanisms of CF action in cellular models. The study population will be composed of elite soccer players randomly allocated to a 12week treatment sequence with normal diet including 40g/day of commercially available dark chocolate (>85% cocoa) or isocaloric diet. Before and after the CF implementation period, maximal aerobic capacity, recovery-stress questionnaire, ECG, real-time three-dimensional echocardiography, flow-mediated dilation and blood samples will be collected. Functional tests on ex-vivo platelets, leukocytes, pro-inflammatory cytokines, markers of oxidative status and circulating microRNAs, isolated from athletes' blood samples, will be carried on to identify cellular targets of CF acute and chronic cardiovascular effects. Since elite athletes are exposed to high levels of oxidative stress impairing their performance and optimal recovery, findings from this study will help athletes being more likely to adhere to their training program, especially during periods of strenuous high-volume loads, with impact on their health and performance.
The present research proposal will investigate the effects of CF dietary implementation as a mechanism to counteract ROS production during exercise by a multifaceted approach, through the evaluation of the acute and chronic effects of CF dietary implementation in elite athletes and the putative molecular mechanisms of CF action in cellular models. This project is ultimately developed to have a comprehensive understanding of CF as a cheap, simple and commercially available dietary implementation in reducing the exercise-induced muscular damage and oxidative stress at individual and cellular level.
An ecological approach will be favored when evaluating elite athletes, without interfering with their regular training and competition schedule, thus maximizing ecological validity and feasibility of the study, as well as increasing relevance and applicability of the results. Since elite athletes are exposed to high levels of oxidative stress impairing their performance and optimal recovery, findings from this study will help athletes being more likely to adhere to their training program, especially during periods of strenuous high-volume loads, with a positive impact not only on their performance but also on their cardiovascular health. By means of a non-invasive strategy provided by dark chocolate consumption to scavenge additional ROS in reducing the oxidative damage in athletes, a consistent frequency of training sessions preventing a decline in exercise performance and optimizing post-exercise recovery could be facilitate. Moreover, as studies combined long-term CF intake with exercise training are lacking, finding from this study could help determine their synergistic effects. As exhaustive exercise, especially when sporadic, causes structural damage to muscle cells or inflammatory reactions within the muscles, the results of the present study could potentially be generalized to a broader population of physically active individuals. In particular, although literature indicates that ROS generated during moderate-intensity PA act as signals to increase the production of enzymes relevant to the adaptation of muscle cells and cardiomyocites, higher intensities lead to ROS production. Indeed, according to the American College of Sports Medicine guidelines, moderate-intensity PA is defined as 3.0 to 6.0 METs, such as walking at a moderate or brisk pace. However, the physical active population, although not involved in competition, is more likely to be engaged in vigorous activities (defined as more than 6.0 METs) such as jogging or running. Therefore, even individuals practicing non-competitive PA are prone to generate high levels of oxidative stress and CF dietary implementation could result in an optimal strategy to successfully counteract ROS production and potentially re-establish a healthy cellular redox balance.
In exploring the mechanisms behind the CF action at individual and cellular levels, also by in-depth analysis, this project will develop innovative approaches in dietary implementation as a tool to contribute to the health of individuals in line with the objective of Horizon 2020 'Societal challenges: Health, well-being and demographic change/Improving the lifelong health and well-being of all'. Actually, findings from this study could provide a significant step-forward in nutraceuticals as a tool to improve health and counteracting exercise related side effects. In particular, chronic CF dietary implementation in conjunction with training has been reported to have positive effects on blood pressure, antioxidant capacity, glucose, and fat metabolism. Moreover, polyphenols supplementation combined with exercise has been recently claimed to have a synergistic effect by increasing muscle lipid oxidation and sparing glycogen utilization able to enhance endurance capacity.
Therefore, findings from this study could provide insights on CF also as a possible strategy to prevent cardiovascular diseases, diabetes, obesity, and cancer.