Puype, J., Ramaekers, M., & Hespel, P. (2013). Chronic nitrate supplementation with training: no effect on O2-efficiency and endurance exercise performance. Medicine & Science in Sports & Exercise, 45(5), Supplement abstract number 2423.

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This study determined if high-intensity endurance training plus nitrate intake increased O2-efficiency during submaximal exercise and exercise performance more than training alone. Healthy males performed bicycle ergometer training (4-6 mmol/L lactate, five 30-minute sessions per week for six weeks), either with beetroot juice (~0.07 mmol/kg/day; N = 10), or with a placebo drink (apple black currant juice, ~0.5 L/day; N = 10). A control group received beetroot juice, but did not train (N = 10). Pre-test and post-test the training period, Ss performed a 30-minute time-trial and a maximal incremental exercise test to exhaustion. Ss received beetroot juice or the placebo from four days before the pre-test to eliminate any acute effects of nitrate intake.

The training increased mean power-output during the time-trial by 13% in the beetroot-juice condition and 11% in the placebo condition. Compared with the control condition, power output at the 4mmol/l lactate threshold measured in the exhaustion-test increased by 17% in the beetroot-juice condition and 11% in the placebo condition. Training increased VO2max in the beetroot-juice and placebo conditions similarly. VO2max was constant throughout the study in the control condition. The training program also prolonged the time to exhaustion to the same degree in the beetroot juice and placebo conditions.

Implication. Chronic nitrate intake during endurance training does not enhance O2-efficiency during submaximal exercise or improve endurance exercise performance.

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