Normobaric Hypoxia as a Strength Training Intensity Amplifier in Ice Hockey Players: Effects on Anaerobic Performance and Muscle Contraction Properties

Study Overview This study will investigate the physiological adaptations elicited by a structured resistance training program conducted under normobaric hypoxic conditions (simulated altitude of approximately 3500 meters) in comparison to normoxic training in elite ice hockey athletes. Specifically, the research will evaluate whether resistance training under hypoxic conditions can enhance anaerobic power output, accelerate lactate clearance kinetics, and positively influence muscle contractile properties. Furthermore, the study will examine the potential for hypoxic conditions to maintain or increase physiological training intensity while utilizing reduced mechanical loads, potentially lowering cumulative musculoskeletal stress. Additionally, the effectiveness of hypoxic training as a rehabilitation tool for injured athletes will be explored, assessing its capacity to preserve performance levels, facilitate recovery, and mitigate rapid detraining during periods of reduced training intensity.

Methods Participants Forty highly trained male ice hockey players will be recruited and randomly assigned to one of four experimental groups, with ten athletes per group (n = 10). All participants will provide written informed consent following a detailed explanation of the potential risks, benefits, and procedural requirements of the study. Inclusion criteria will stipulate that athletes have engaged in elite-level ice hockey training for at least three years and have no significant injury history within the preceding three months. Throughout the intervention period, participants will be instructed to maintain their habitual training routines, dietary practices, and recovery strategies to minimize potential confounding influences.

Study Design This investigation will be designed as a randomized controlled trial to compare the physiological effects of resistance training performed under normobaric hypoxia (simulated altitude equivalent to 3500 meters) versus normoxic conditions. Participants will be randomly allocated into one of four distinct intervention groups: (1) high-intensity training under normoxia (H-N), (2) low-intensity training under normoxia (L-N), (3) high-intensity training under hypoxia (H-H), and (4) low-intensity training under hypoxia (L-H). The training intervention will last six weeks, with each participant completing two supervised training sessions per week (totaling twelve sessions). Training adherence, technique consistency, and participant safety will be strictly monitored by experienced investigators throughout the study.

All training sessions will involve a standardized leg press exercise performed on identical equipment (a 45-degree plate-loaded leg press machine). Training loads, intensities, and repetition schemes will differ systematically based on group allocation. Athletes assigned to high-intensity training groups (H-N and H-H) will perform four sets of ten repetitions per session at 70-80% of their predetermined one-repetition maximum (1RM). Training load progression will be implemented systematically, beginning at 70% of 1RM during weeks 1-3 and increasing to 80% of 1RM during weeks 4-6. In contrast, athletes in low-intensity groups (L-N and L-H) will perform four sets per session using a repetition scheme of 30 repetitions in the first set, followed by three sets of 15 repetitions each (30/15/15/15), with loading progressing from 20% of 1RM in weeks 1-3 to 30% of 1RM in weeks 4-6.

All exercises will be executed with a controlled movement tempo (approximately two seconds for the eccentric phase and one second for the concentric phase). Rest periods will be standardized across groups: two minutes between sets for high-intensity groups and one minute between sets for low-intensity groups. Each session will begin with a standardized warm-up (five minutes of cycling at 100 W and one warm-up set at approximately 50% of the prescribed load) and conclude with a standardized cooldown (five minutes of cycling at 50 W). Load adjustments will be conducted weekly based on continuous monitoring to maintain the intended training intensity and progression.