Effects of Hypoxic Repeated Sprint Training on Performance in Normoxia in Male and Female Athletes Participating in Team/Racket Sports

With the increased participation of women in sports, it is essential to develop gender-tailored training strategies for improving exercise performance. Males and females exhibit gender-specific characteristics and they therefore respond differently to physical exercise. Improving repeated sprint ability (RSA, i.e., ability to perform repeated short duration sprints separated by brief recovery intervals) in women is important for sports performance, as it is a key factor in most team and racket sports. Repeated sprint training in hypoxia is increasingly popular in this field, as it has demonstrated further improvements in sea-level repeated sprint performance than similar training in normoxia. However, these observations are based mainly on male athletes. Whether the effects of hypoxic repeated sprint training on repeated sprint performance in normoxia differ between genders is not yet known, therefore the investigators propose to examine those possible differences in this study.

The aim of this study is to investigate whether the effects of hypoxic repeated sprint training on repeated sprint performance in normoxia differ between males and females who participate in team/racket sports.

Considering the sex-specific characteristics that males and females exhibit, the investigators hypothesize that after 7 weeks of hypoxic repeated sprint training the improvements in repeated sprint ability at sea level will be greater in males than in females.

To answer this question, the investigators will measure the following: body composition (lean body mass); body weight and height; VO2max; blood (estrogen, lactate, hemoglobin, hematocrit); repeated sprint ability (RSA) test; muscle oxygenation (concentrations for oxyhemoglobin, deoxyhemoglobin, and total hemoglobin/myoglobin); 30-s Wingate test; heart rate (HR); power output; rate of perceived exertion (RPE); visual analogue scale (VAS; pain level in legs).

The investigators will recruit 48 volunteers and they will randomly assign them into the normoxic or hypoxic training group, without giving any information about their group. The volunteers should meet the following inclusion criteria: females (on monophasic oral contraceptive pill) and males, age between 18-40 years, recreationally participating in team/racket sports min 3h/week with at least 2 years of experience prior to the study. Exclusion criteria will be: smoking, exposure to altitude >1500 m one month before the study, any health conditions or injuries that could compromise the participant's safety during training/testing, prescribed medication, performing repeated sprint training more than once per week.

Males and females, matched for VO2max and sprint performance, will perform repeated sprint training (3 sets during week 1-6, 2 sets during week 7 with 5min active recovery in between, 5 x 10s maximal sprints with 20s active recovery in between) in hypoxia or normoxia 2x/week for 7 weeks. Before and after the training period, the following tests and measurements will be performed: body composition analysis, VO2max test, blood sampling for measuring hemoglobin and estrogen concentrations and hematocrit, determination of hemoglobin mass, RSA test, muscle oxygenation assessment during RSA test, 30-s Wingate test and blood lactate measurements.