LAUSR

PURPOSE To investigate the effectiveness of a novel repeated-sprint training in hypoxia (RSH) protocol, likely maximizing hypoxic stimulus (higher than commonly used) while preserving training quality (inter-sets rest in normoxia). METHODS Twenty-three world-class female rugby sevens players performed four repeated-sprint training sessions (4 sets of 5 × 5-s cycle sprints - 25-s inter-sprint recovery and 3-min inter-set rest) under normobaric hypoxia (RSH; exercise and inter-set rest at FiO2 10.6% and 20.9%, respectively; n = 12) or normoxia (RSN; exercise and inter-set rest at FiO2 20.9%; n = 11) during a 9-d training camp prior to international competition. Repeated-sprint ability (8 × 5-s treadmill sprints - 25-s recovery), on-field aerobic capacity and brachial endothelial function were assessed Pre- and Post-intervention. RESULTS Arterial oxygen saturation (pooled data: 87.0 ± 3.1% vs. 96.7 ± 2.9%, P < 0.001) and peak and mean power outputs (set 1-4 average decrease: -21.7 ± 7.2% vs. -12.0 ± 3.8% and -24.9 ± 8.1% vs. -14.9 ± 3.5%; both P < 0.001) were lower in RSH vs. RSN. Cumulated repeated-sprint distance covered significantly increased from Pre- to Post-intervention (+1.9 ± 3.0%; P = 0.019), irrespective of condition (P = 0.149). On-field aerobic capacity did not change (all P > 0.45). There was no significant interaction (all P > 0.240) or condition main effect (all P > 0.074) for any brachial artery endothelial function variable. Only peak diameter increased (P = 0.026), while baseline and peak shear stress decreased (P = 0.014 and 0.019, respectively), from Pre- to Post-intervention. CONCLUSIONS In world-class female rugby sevens players, only four additional repeated-sprint sessions before competition improve repeated-sprint ability and brachial endothelial function. However, adding severe hypoxic stress during sets of repeated sprints only did not provide supplementary benefits.