Abstract
IntroductionHypoxia has been used for several decades to improve exercise performance. Recently, addition of hypoxic stimulus to repeated sprints within training emerged as a new way to maximize performance in repeated sprint ability (RSA) as compared to normoxia (1). Repeated sprint training under hypoxia (RSH) is able to increase performance in moderately active students (2) as well as international rugby players (3) even with a very low number of training sessions. Decline in arterial oxygen saturation usually observed when inhaling hypoxic gas mixture presents great inter-individual variations during RSH. This suggests that the hypoxic stimulus can differ among athletes involved in a same training. Lastly, although most studies were performed at simulated altitudes near 3000m, there is no clear consensus about either the optimal altitude or pulse oxygen saturation (SpO2) level to set for getting the highest exercise performance. Within this context, the use of SpO2 to individualize the hypoxic dose is of particular importance. Therefore, this study aims to determine whether performance improvement following RSH depends upon the level of desaturation over the training sessions.MethodsTwenty-one male students from the sport sciences faculty (age 21.7 ± 1.4; height 176.3 ± 7.8; weight 68.5 ± 6.3) voluntary participated to 6 sessions of RSH over two weeks at simulated altitude of 1500m (n=7), 2100m (n=7) or 3200m (n=7). Training sessions consisted of 3 sets of 8 repetitions of 6 s sprint interspersed by 24 s of passive recovery on a cycle ergometer. The subjects performed a Wingate test and an RSA test (10 sprints of 6 s interspersed by 24 s of passive recovery) on separated days before and after the training. Peak and mean power outputs were monitored for each test (PowerTap P1 pedals). Lactatemia was measured at rest and 2 and 3 min post-exercise for RSA tests, and 5 and 6 min post-exercise for Wingate tests (Lactate Scout+). SpO2 was continuously monitored at 1 Hz (pulsox®-300i) and the rate of perceived exertion (RPE) was recorded after each set during RSH sessions.ResultsMean SpO2 during training sessions was significantly negatively correlated with altitude level and different between all the three groups, while RPE was not different between groups. RSH significantly increased mean and peak power outputs during the Wingate test in all the three groups. Lactatemia after the Wingate test was enhanced following RSH, an effect that was potentiated in the 3200m group. This increase in lactatemia was negatively correlated with SpO2 during RSH (p=0.03, r²=0.23). Peak power across the RSA test was significantly improved by training without difference between groups. Mean power during the RSA test was increased after RSH in the 1500 and the 2100 groups, but not in the 3200 group. None of the variations in performance following training were correlated with SpO2 during RSH.DiscussionRSH is effective for improving anaerobic power and capacity. However, there is no clear evidence that gains of performance depend upon the severity of hypoxia during training sessions. Our results are in line with recent data obtained on sprint interval training conducted at different altitudes (4).ConclusionSix sessions of RSH increased anaerobic performance, whatever the altitude level used.References1)Brocherie et al., Sports Med, 2017, doi: 10.1007/s40279-017-0685-32)Camacho-Cardenosa et al., J Sports Med Phys Fitness, 2017, doi: 10.23736/S0022-4707.16.06549-X3)Beard et al., Int J Sports Physiol Perform, 2019, doi: 10.1123/ijspp.2018-01704)Warnier et al., Sports, 2020, doi: 10.3390/sports8110148