Author(s): HAGIWARA, M., YAMAGISHI, T., YAMASHITA, D. , Institution: JAPAN HIGH PERFORMANCE SPORT CENTER, Country: JAPAN, Abstract-ID: 1701

INTRODUCTION:
Repeated sprint training in hypoxia (RSH) has gained popularity among high-performance sports because it brings about various training benefits in a time-efficient manner [1]. Indeed, 2-5 weeks of RSH has been shown to improve anaerobic power, repeated sprint ability, and aerobic power [1]. While repeated sprint training in normoxia (RSN) also induced physiological adaptations such as maximal oxygen uptake (VO2max) within 3 weeks, no further improvements of VO2max were observed with additional 3-6 weeks of the training despite an increase in training volume (number of sets) [2]. This suggests that increase in training volume alone is not sufficient for further physiological adaptations. Thus, this study aimed to evaluate the effects of additional hypoxic stimulus while simultaneously increasing training volume.
METHODS:
Sixteen highly-trained basketball players (age: 20 ± 1 years, height: 182.6 ± 7.8 cm, weight: 74.8 ± 8.4 kg, VO2max: 55.2 ± 5.4 ml/min/kg) completed physiological and performance tests on a cycle ergometer (Wattbike ATOMX) three times: before, during and after the training intervention (Pre, Mid, Post). Main parameters were peak power (PP) and mean power (MP) during a 6-s cycle sprint test, and maximal aerobic power (MAP) and VO2max achieved in a cycle incremental test. All subjects performed RSN with maximal efforts 3 times per week for 2 weeks (i.e., 6 sessions in total) as the first half of the training (2 sets of 5-7 6-s sprints with 30-s recovery, 5-min recovery between the sets), after which they were divided into 2 groups (hypoxic training group: HYP, normoxic training group: NOR) based on the results obtained from Pre and Mid tests. The second half of the training consisted of 3 sets of 5-7 6-s sprints with 30-s recovery, 5-min recovery between the sets, where HYP completed 5 sessions under normobaric hypoxia (FIO2: 14.5%, equivalent to a simulated altitude of 3000 m) with one more session under normoxia (i.e., 6 sessions in total), whereas NOR completed 6 sessions under normoxia.
RESULTS:
Both groups significantly improved PP and MP from Pre to Post (PP [Pre vs. Post]: HYP, 14.8 ± 2.2 vs. 16.4 ± 1.5 W/kg; NOR, 14.1 ± 1.5 vs. 15.2 ± 2.0 W/kg, p < .05, MP [Pre vs Post]: HYP, 12.5 ± 1.8 vs. 13.9 ± 1.2 W/kg; NOR, 11.7 ± 0.9 vs. 13.0 ± 1.6 W/kg, p < .01) with no difference between the groups. Both groups significantly improved MAP and VO2max from pre to Post (MAP [Pre vs. Post]: HYP, 4.26 ± 0.35 vs. 4.42 ± 0.31 W/kg; NOR, 4.02 ± 0.36 vs. 4.28 ± 0.30 W/kg, p < .001, VO2max [Pre vs. Post]: HYP, 57.2 ± 4.2 vs. 60.2 ± 3.6 ml/kg/min; NOR, 53.0 ± 6.2 vs. 56.4 ± 5.3 ml/kg/min, p < .001) with no difference between the groups.
CONCLUSION:
12 sessions of repeated sprint training over 4 weeks improved both anaerobic and aerobic capacities, whereas no additional benefits were obtained from 5 sessions of RSH when preceded by 6 sessions of RSN over 2 weeks.

References
1. Brocherie et al. (2017)
2. Yamagishi & Babraj (2017)