Acute Effect of Normobaric Hypoxia on Performance in Repeated Wingate Tests with Longer Recovery Periods and Neuromuscular Fatigue in Triathletes: Sex Differences

Background: Repeated high-intensity intervals under normoxic (NOR) and hypoxic (HYP) conditions is a training strategy used by athletes. Although different protocols have been used, the effect of longer recovery between repetitions is unclear. In addition, information on the effect of repeated high-intensity intervals on HYP in women is scarce. Aims: To analyse the differences between sexes and between conditions (NOR and HYP) in Repeated Wingate (RW) performance and neuromuscular fatigue in triathletes. Methods: A total of 12 triathletes (men: n = 7, 23.00 ± 4.04 years; women: n = 5, 20.40 ± 3.91) participated in this randomised, blinded, crossover study. In two separate sessions over seven days, participants performed 3 × 30” all out with 7′ of recovery in randomised NOR (fraction of inspired oxygen: ≈20%; ≈300 m altitude) and HYP (fraction of inspired oxygen: ≈15.5%; ≈2500 m altitude) conditions. Before and after RW, vertical jump tests were performed to assess neuromuscular fatigue. Oxygen saturation, power, perceived exertion, muscle soreness and heart rate parameters were assessed. Results: Significant differences were reported between sexes in the parameters of vertical jump, oxygen saturation, RW performance and heart rate (p < 0.05). However, between conditions (NOR and HYP), only differences in oxygen saturation were reported (p < 0.05). No significant differences were reported between conditions (NOR and HYP) in RW performance, neuromuscular fatigue, muscle soreness and perception of exertion. Conclusions: A 3 × 30” RW protocol with 7′ recovery in HYP could have no negative consequences on performance, neuromuscular fatigue and perception of exertion in triathletes compared to NOR, independently of sex.