Combined Effects of Normobaric Hypoxia and Resistance Training Intensity on Anaerobic Performance, Lactate Kinetics, and Neuromuscular Function in Trained Ice Hockey Players: A randomized trial

Abstract Background Ice hockey requires a specific combination of physical attributes, including explosive power, speed, agility, and specific metabolic capacities. This study aimed to determine whether hypoxic conditions during resistance training at high and low intensity enhance anaerobic power, lactate kinetics, and neuromuscular function compared to normoxic conditions in highly trained ice hockey players. Methods In this randomized, four-arm, parallel-group trial, forty male ice hockey athletes (aged 18–25 years) were randomly allocated to four groups and performed either normoxic or normobaric hypoxic resistance training at high (80% of one repetition maximum – 1RM) or low intensity (30% of 1RM) twice a week for six weeks. Pre and post-tests were done for one repetition maximum leg press, anaerobic performance (30s Wingate test), lactate kinetics, and muscle contractility by tensiomyography. Data were analysed using 2 × 4 (Time × Group) mixed-design repeated-measures ANOVA with Bonferroni-corrected post hoc comparisons. Results All groups improved their 1RM leg press with no differences between groups. Peak power increased, and time to peak power during the Wingate test decreased after high-intensity resistance training in normoxia (N-H) and high-intensity resistance training in hypoxia (H-H) (p< 0.001). The H-H and N-H groups showed a higher power decline in repeated Wingate (p< 0.001). The low load hypoxia training (H-L) improved lactate clearance, increased HCO3act decline, and decreased pH decline (p<0.001). Vastus lateralis contraction time increased in the N-H group (p=0.021), and contraction displacement decreased in H-H. Conclusions Crucially, hypoxic resistance training does not uniformly enhance all performance outcomes; rather, it produces specific, intensity-dependent adaptations. The intensity of resistance training elicits a superior training response to hypoxia, enhancing power in ice hockey players. Trial registration ClinicalTrials.gov, NCT06930027, registered retrospectively on 08 April 2025.