Researchers postulate that flavanol, contained in dark chocolate, may improve performance by increasing muscle efficiency, similar to performance-enhancing foods containing nitrate
Athletes seeking natural ways to improve endurance or overall performance have turned in recent years to drinking beet juice, which is rich in nitrate. It is believed that having higher levels of circulating nitrite, which gets converted to nitric oxide (NO), lowers blood pressure and improves muscle efficiency, which in turn, results in muscles requiring less oxygen to maintain the same level of performance. The downside, however, is that many people find the taste of beet juice unpalatable, and thus unpleasant as a daily dietary supplement.
In a recent study published in the Journal of the International Society of Sports Nutrition, researchers looked at whether dark chocolate could be a viable performance-enhancing substitute for beet juice. Dark chocolate is rich in flavanols, which are compounds known to increase the rate at which NO is absorbed into circulation and available for use. The theory behind the study was that regular consumption of dark chocolate might, like beet juice, result in increased muscle efficiency, and provide similar performance enhancements.
The study was done on nine moderately-trained male participants. At the start of the study, measurements were taken of each participant’s maximum oxygen volume (VO2 max), oxygen consumption, respiratory exchange ratio (RER), gas exchange threshold (GET), heart rate and blood lactate (BLa) while cycling at different intensities and distances. The participants were then randomly assigned to consume daily amounts of either dark chocolate or white chocolate for a period of two weeks, after which measurements were taken again while cycling. Participants then switched the type of chocolate they ate (dark or white) for a further period of two weeks, and a final set of measurements was taken.
The results showed a 21% increase in the GET after two weeks of dark chocolate consumption, compared with an 11% increase after white chocolate. In addition, the distance covered by cyclists in 2-minute sprint time trials increased by 17% with dark chocolate, versus 13 % with white chocolate. However, other measures, such as VO2, RER, BLa, or heart rate showed no significant change during moderate intensity cycling. Furthermore, there was no difference in systolic BP and diastolic BP.
The specific mechanisms underlying the increase in GET and the two-minute sprint are not explained by the study. However, researchers suggest that, based on these results, flavanol contained in dark chocolate may be responsible for eliciting the observed effects, and may be a compound of interest for further research.
Written By: Linda Jensen