Five Days of Tart Cherry Supplementation Improves Exercise Performance in Normobaric Hypoxia

Previous studies have shown tart cherry (TC) to improve exercise performance in normoxia. The effect of TC on hypoxic exercise performance is unknown. This study investigated the effects of 5 days of tart cherry (TC) or placebo (PL) supplementation on hypoxic exercise performance. Thirteen healthy participants completed an incremental cycle exercise test to exhaustion (TTE) under two conditions: (i) hypoxia (13% O-2) with PL and (ii) hypoxia with TC (200 mg anthocyanin per day for 4 days and 100 mg on day 5). Pulmonary gas exchange variables, peripheral arterial oxygen saturation (SpO(2)), deoxygenated hemoglobin (HHb), and tissue oxygen saturation (StO(2)) assessed by near-infrared spectroscopy in the vastus lateralis muscle were measured at rest and during exercise. Urinary 8-hydro-2 ' deoxyguanosine (8-OHdG) excretion was evaluated pre-exercise and 1 and 5 h post-exercise. The TTE after TC (940 +/- 84 s, mean +/- standard deviation) was longer than after PL (912 +/- 63 s, p < 0.05). During submaximal hypoxic exercise, HHb was lower and StO(2) and SpO(2) were higher after TC than PL. Moreover, a significant interaction (supplements x time) in urinary 8-OHdG excretion was found (p < 0.05), whereby 1 h post-exercise increases in urinary 8-OHdG excretion tended to be attenuated after TC. These findings indicate that short-term dietary TC supplementation improved hypoxic exercise tolerance, perhaps due to lower HHb and higher StO(2) in the working muscles during submaximal exercise.