Ten trained male team-sport athletes completed @ sets of repeated sprints ( @ @ s ) on a nonmotorized treadmill at sea level and at simulated altitudes of @ , @ , and @ m. Participants completed @ trials in a random order over @ wk , with mean power output ( MPO ) , peak power output ( PPO ) , blood lactate concentration ( Bla ) , and oxygen saturation ( SaO@ ) recorded after each set .