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Bryan Saunders, Craig Sale, Roger C. Harris, and Caroline Sunderland

Purpose:

To investigate the separate and combined effects of sodium bicarbonate and beta-alanine supplementation on repeated sprints during simulated match play performed in hypoxia.

Methods:

Study A: 20 recreationally active participants performed two trials following acute supplementation with either sodium bicarbonate (0.3 g·kg−1BM) or placebo (maltodextrin). Study B: 16 recreationally active participants were supplemented with either a placebo or beta-alanine for 5 weeks (6.4 g·day−1 for 4 weeks, 3.2 g·day−1 for 1 week), and performed one trial before supplementation (with maltodextrin) and two following supplementation (with sodium bicarbonate and maltodextrin). Trials consisted of 3 sets of 5 × 6 s repeated sprints performed during a football specific intermittent treadmill protocol performed in hypoxia (15.5% O2). Mean (MPO) and peak (PPO) power output were recorded as the performance measures.

Results:

Study A: Overall MPO was lower with sodium bicarbonate than placebo (p = .02, 539.4 ± 84.5 vs. 554.0 ± 84.6 W), although there was no effect across sets (all p > .05). Study B: There was no effect of beta-alanine, or cosupplementation with sodium bicarbonate, on either parameter, although there was a trend toward higher MPO with sodium bicarbonate (p = .07).

Conclusions:

The effect of sodium bicarbonate on repeated sprints was equivocal, although there was no effect of beta-alanine or cosupplementation with sodium bicarbonate. Individual variation may have contributed to differences in results with sodium bicarbonate, although the lack of an effect with beta-alanine suggests this type of exercise may not be influenced by increased buffering capacity.

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Colin R. Carriker, Christine M. Mermier, Trisha A. VanDusseldorp, Kelly E. Johnson, Nicholas M. Beltz, Roger A. Vaughan, James J. McCormick, Nathan H. Cole, Christopher C. Witt, and Ann L. Gibson

Reduced partial pressure of oxygen impairs exercise performance at altitude. Acute nitrate supplementation, at sea level, may reduce oxygen cost during submaximal exercise in hypobaric hypoxia. Therefore, we investigated the metabolic response during exercise at altitude following acute nitrate consumption. Ten well-trained (61.0 ± 7.4 ml/kg/min) males (age 28 ± 7 yr) completed 3 experimental trials (T1, T2, T3). T1 included baseline demographics, a maximal aerobic capacity test (VO2max) and five submaximal intensity cycling determination bouts at an elevation of 1600 m. A 4-day dietary washout, minimizing consumption of nitrate-rich foods, preceded T2 and T3. In a randomized, double-blind, placebo-controlled, crossover fashion, subjects consumed either a nitrate-depleted beetroot juice (PL) or ~12.8 mmol nitrate rich (NR) beverage 2.5 hr before T2 and T3. Exercise at 3500 m (T2 and T3) via hypobaric hypoxia consisted of a 5-min warm-up (25% of normobaric (VO2max) and four 5-min cycling bouts (40, 50, 60, 70% of normobaric VO2max) each separated by a 4-min rest period. Cycling RPM and watts for each submaximal bout during T2 and T3 were determined during T1. Preexercise plasma nitrite was elevated following NR consumption compared with PL (1.4 ± 1.2 and 0.7 ± 0.3 uM respectively; p < .05). There was no difference in oxygen consumption (−0.5 ± 1.8, 0.1 ± 1.7, 0.7 ± 2.1, and 1.0 ± 3.0 ml/kg/min) at any intensity (40, 50, 60, 70% of VO2max), respectively) between NR and PL. Further, respiratory exchange ratio, oxygen saturation, heart rate and rating of perceived exertion were not different at any submaximal intensity between NR and PL either. Blood lactate, however, was reduced following NR consumption compared with PL at 40 and 60% of VO2max (p < .0.05). Our findings suggest that acute nitrate supplementation before exercise at 3500 m does not reduce oxygen cost but may reduce blood lactate accumulation at lower intensity workloads.

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Adam Beard, John Ashby, Ryan Chambers, Franck Brocherie, and Grégoire P. Millet

This may have good carryover to rugby union, which has a high number of repeated-sprint requirements. 2 Although RSA training is well accepted to improve this quality, 5 utilizing RSA in hypoxic conditions (the so-called “repeated-sprint training in hypoxia,” [RSH]) has shown superior results when

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Erin L. McCleave, Katie M. Slattery, Rob Duffield, Stephen Crowcroft, Chris R. Abbiss, Lee K. Wallace, and Aaron J. Coutts

Challenging environmental conditions such as heat or hypoxia increase physiological demand during endurance exercise and may impair physical performance. 1 , 2 Repeated exposure to heat or hypoxia elicits physiological responses to reduce strain during exercise and minimizes the negative impact on

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Naoya Takei, Jacky Soo, Hideo Hatta, and Olivier Girard

Repeated 30-second Wingates (RW), a popular form of sprint interval training, can improve aerobic and anaerobic capacities. 1 Although the majority of RW training studies have been conducted in normoxia, performing this workout with the addition of hypoxia likely induces greater physiological

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Ben J. Lee and Charles Douglas Thake

cardiovascular strain during BWS exercise. To the best of the authors’ knowledge, no published data are available to inform the practice of exposing individuals to reduced amounts of O 2 during BWS. It would of interest to determine whether the increased physiological strain imparted by hypoxia during BWS can

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Naoya Takei, Katsuyuki Kakinoki, Olivier Girard, and Hideo Hatta

“Live low train high” altitude/hypoxic training methods such as intermittent hypoxic training, in which athletes live near sea level (normoxia) but train at submaximal intensities under simulated hypoxia are popular. 1 , 2 Exercising under hypoxic conditions likely represents a more powerful

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Sarah J. Willis, Grégoire P. Millet, and Fabio Borrani

During conditions of systemic hypoxia and/or ischemia via vascular occlusion (blood flow restriction, BFR), there is reduced oxygen availability. The different intrinsic vascular mechanisms of hypoxia-induced compensatory vasodilation 1 or BFR-induced increased vascular resistance 2 may influence

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Erin L. McCleave, Katie M. Slattery, Rob Duffield, Philo U. Saunders, Avish P. Sharma, Stephen Crowcroft, and Aaron J. Coutts

Exercise in environments such as hypoxia or heat acutely increases physiological strain and reduces performance capacity. 1 – 3 Repeated exposure to hypoxia drives hematological and muscular adaptations to improve aerobic capacity in both hypoxic and normoxic environments. 4 Heat training and

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Xiao Bao, Jie-Wen Tan, Ying Long, Howe Liu, and Hui-Yu Liu

repetitive transcranial magnetic stimulation, have few effects for dizziness. 5 It remains a challenge for physicians. Therefore, new approaches in the treatment of dizziness are needed. Intermittent hypoxia training (IHT) is initially recognized by the sports medicine community as a potentially useful