European journal of applied physiology | 2021
Effect of hypoxia and nitrate supplementation on different high-intensity interval-training sessions.
Abstract
PURPOSE\nTo test the hypothesis that interval-training (IHT) would be impaired by hypoxia to a larger extent than repeated-sprint training (RSH) and that dietary nitrate (NO3-) would mitigate the detrimental effect of hypoxia to a larger extent during IHT than RSH.\n\n\nMETHODS\nThirty endurance-trained male participants performed IHT (6\u2009×\u20091\xa0min at 90%∆ with 1\xa0min active recovery) and RSH (2 sets of 6\u2009×\u200910\xa0s all-out efforts with 20\xa0s active recovery) on a cycle ergometer, allocated in one of three groups: normobaric hypoxia (~\u200913% FiO2)\u2009+\u2009NO3-\xa0-\xa0HNO, n\u2009=\u200910; normobaric hypoxia\u2009+\u2009placebo\xa0-\xa0HPL, n\u2009=\u200910; normoxia (20.9% FiO2)\u2009+\u2009placebo\xa0-\xa0CON, n\u2009=\u200910. Submaximal oxygen uptake ([Formula: see text]O2), time spent above 90% of maximal [Formula: see text]O2 (≥\u200990 [Formula: see text]O2max) and heart rate (≥\u200990 HRmax) were compared between IHT and RSH sessions and groups. Additionally, mean power output (MPO), decrement score and % of power associated with [Formula: see text]O2max (%p[Formula: see text]O2max) in RSH sessions were analyzed.\n\n\nRESULTS\n[Formula: see text]O2 at sub-maximal intensities did not differ between training protocols and groups (~\u200927\xa0ml\xa0kg-1\xa0min-1). \u2009≥\u200990 HRmax was significantly higher in IHT compared to RSH session (39\u2009±\u20098 vs. 30\u2009±\u20098%, p\u2009=\u20090.03) but only in HNO group. MPO (range 360-490\xa0W) and decrement score (10-13%) were similar between groups although %p[Formula: see text]O2max was significantly higher (p\u2009=\u20090.04) in CON (166\u2009±\u200916\xa0W) compared with both HPL (147\u2009±\u200915\xa0W) and HNO (144\u2009±\u200910\xa0W) groups.\n\n\nCONCLUSION\nIHT responses were neither more impaired by hypoxia than RSH ones. Moreover, dietary NO3- supplementation impacted equally IHT and RSH training responses differences between hypoxia and normoxia.