AUTHOR=Schwarz Neil A. , Blahnik Zachary J. , Prahadeeswaran Srihari , McKinley-Barnard Sarah K. , Holden Shelley L. , Waldhelm Andy 

TITLE=(–)-Epicatechin Supplementation Inhibits Aerobic Adaptations to Cycling Exercise in Humans

JOURNAL=Frontiers in Nutrition

VOLUME=5

YEAR=2018

URL=https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2018.00132

DOI=10.3389/fnut.2018.00132

ISSN=2296-861X

ABSTRACT=<p>The purpose of the study was to determine if cycling exercise combined with (–)-epicatechin supplementation was more effective at increasing training adaptations than cycling combined with a placebo. Blood and muscle samples were obtained at rest before and after training to determine the effects of (–)-epicatechin supplementation on total serum antioxidant capacity, skeletal muscle mitochondrial protein content, and skeletal muscle myostatin gene expression. Participants (<italic>n</italic> = 20) completed two testing sessions separated by 4 weeks of cycle training, with supplementation of 100 mg (200 mg total daily) of (–)-epicatechin or a placebo, twice daily. Data were analyzed using a two-way mixed model ANOVA for each variable and the alpha level was set at <italic>p</italic> ≤ 0.05. A significant increase was observed for time for relative peak anaerobic power (<italic>p</italic> &lt; 0.01), relative anaerobic capacity (<italic>p</italic> &lt; 0.01), and fatigue index (<italic>p</italic> &lt; 0.01). A significant increase was observed for time for absolute peak VO<sub>2</sub> (<italic>p</italic> &lt; 0.01) and peak power output obtained during the peak VO<sub>2</sub> test (<italic>p</italic> &lt; 0.01). A significant interaction between group and time for relative peak VO<sub>2</sub> was observed (<italic>p</italic> = 0.04). Relative peak VO<sub>2</sub> significantly increased over time in the placebo group (<italic>p</italic> &lt; 0.01), but not in the (–)-epicatechin group (<italic>p</italic> = 0.21). A significant increase was observed for time for total serum antioxidant capacity (<italic>p</italic> = 0.01). No interaction or main effect of time was observed for myostatin (<italic>p</italic> &gt; 0.05). Likewise, no interaction or main effect of time was observed for cytochrome C or citrate synthase (<italic>p</italic> &gt; 0.05). A significant interaction effect was observed for succinate dehydrogenase (SDH; <italic>p</italic> = 0.02). SDH content increased significantly for the placebo group (<italic>p</italic> = 0.03, partial η<sup>2</sup> = 0.59), but not for the (–)-epicatechin group (<italic>p</italic> = 0.81). Further, whereas no difference existed between the groups for SDH at baseline (<italic>p</italic> = 0.23), SDH content was significantly greater in the placebo group at the post time point (<italic>p</italic> = 0.01). Results indicate that (–)-epicatechin supplementation does not affect myostatin gene expression or anaerobic training adaptations but inhibits aerobic and mitochondrial SDH adaptations to cycle exercise training.</p>