In a double-blind, randomized, cross-over fashion, researchers gave 9 active males 0.5 L/day (17 ounces) of beetroot juice (BRJ) (~6.2 mmol nitrate; brand: Beet it) or nitrate-depleted beetroot juice as placebo (PL) for 6 days (10 day washout). Walking/ running tests on days 4 and 5 were performed, and knee-extensions were performed on day 6. Results indicate that plasma nitrite increased significantly in the BRJ group compared to PL (105%). Systolic blood pressure decreased 4% in the BRJ (BRJ: 124 mmHg, PL: 129 mmHg), while diastolic blood pressure and mean arterial pressure did not change. Additionally, BRJ reduced VO2 (oxygen consumption) during the baseline walking by ~12%, as well as during the last 30 seconds of moderate-intensity running by ~7%. Pulmonary VO2 response was also reduced by ~4%, and the oxygen cost of running 1 km by ~6%. During severe-intensity exercise, BRJ again reduced VO2 during walking, by ~14% compared to PL. BRJ increased time to failure by ~15% (BRJ: 8.7 min vs PL: 7.5 min). At failure, VO2 was ~6% lower in the BRJ group. Knee-extensions were used to measure phosphocreatine concentration which is depleted following an intense work out. Task to failure was longer after the 6 days of BRJ consumption compared to PL: BRJ: 8.5 min, PL: 8.2 min. In summary, this study established that the nitrate in beetroot juice has positive effects on exercise. As nitrite concentration increased, systolic blood pressure decreased, the oxygen cost of walking, moderate-intensity, and severe-intensity running was reduced, and the time to failure in severe-intensity running and the incremental knee-extensions was extended. (8)
