Participants

A total of 29 recreationally-active men and women (exercised for 30 min at least twice per week, on average, for at least the past 6 months) between 18 and 30 years of age [(–)-epicatechin (EPI) group: 20.5 ± 1.5 years.; placebo (PLA) group: 21.0 ± 1.9 years.] were recruited to participate in this study. Participants considered as a low risk for cardiovascular disease, as outlined by the American College of Sports Medicine (ACSM), and who were not consuming nutritional supplements deemed an ergogenic aid for exercise performance, were allowed to enter the study. Exclusion criteria included prior lower extremity surgeries or indication of current or past health conditions, as noted on a health history questionnaire, which limited participation in exercise. The study was approved by the University of South Alabama Institutional Review Board. All participants provided written informed consent prior to enrollment after receiving both oral and written information about the study. All experimental procedures involved in the study conformed to the ethical consideration of the Declaration of Helsinki.

Overall, 20 of the 29 participants completed the study. Of the 9 participants that withdrew from the study; reasons for withdrawal included muscle injury (1), knee soreness (1); flu/cold type illnesses (2), heart palpitations [1; placebo group], family/schedule conflicts (2), and personal reasons (2). One participant experienced a hypoglycemic fainting episode after the last training session (placebo group), and thus did not participate in the post-training exercise testing for safety reasons; however, the participant still donated post-testing blood and muscle samples. Another participant was unable to complete the post-exercise peak oxygen consumption test because of equipment malfunction. Additionally, only 22 of the original 29 participants agreed to donate blood and muscle samples, and 16 of these participants completed the entire study. See Figure ​Figure11 for a flow diagram of participants and Table ​Table11 for participant characteristics for those who completed the entire study at baseline.

Participant flow chart.

Participant Baseline Characteristics.