A clustered repeated-sprint running protocol for team-sport athletes performed in normobaric hypoxia

The present study compared the performance (peak speed,distance,and acceleration) of ten amateur team-sport athletes during a clustered (i.e.,multiple sets) repeated-sprint protocol,(4 sets of 4,4-s running sprints; i.e.,rsr444) in normobaric normoxia (fio2 = 0.209; i.e.,rsn) with normobaric hypoxia (fio2 = 0.140; i.e.,rsh). subjects completed two separate trials (i. rsn,ii. rsh; randomised order) between 48 h and 72 h apart on a non-motorized treadmill. in addition to performance,we examined blood lactate concentration [la-] and arterial oxygen saturation (spo2) before,during,and after the rsr444. while there were no differences in peak speed or distance during set 1 or set 2,peak speed (p = 0.04 and 0.02,respectively) and distance (p = 0.04 and 0.02,respectively) were greater during set 3 and set 4 of rsn compared with rsh. there was no difference in the average acceleration achieved in set 1 (p = 0.45),set 2 (p = 0.26),or set 3 (p = 0.23) between rsn and rsh; however,the average acceleration was greater in rsn than rsh in set 4 (p < 0.01). measurements of [la-] were higher during rsh than rsn immediately after sprint 16 (10.2 ± 2.5 vs 8.6 ± 2.6 mm; p = 0.02). estimations of spo2 were lower during rsh than rsn,respectively,immediately prior to the commencement of the test (89.0 ± 2.0 vs 97.2 ± 1.5 %),post sprint 8 (78.0 ± 6.3 vs 93.8 ± 3.6 %) and post sprint 16 (75.3 ± 6.3 vs 94.5 ± 2.5 %; all p < 0.01). in summary,the rsr444 is a practical protocol for the implementation of a hypoxic repeated-sprint training intervention into the training schedules of team-sport athletes. however,given the inability of amateur team-sport athletes to maintain performance in hypoxic (fio2 = 0.140) conditions,the potential for specific training outcomes (i.e. speed) to be achieved will be compromised,thus suggesting that the rsr444 should be used with caution. © journal of sports science and medicine.