Mj. Brosnan et al., Impaired interval exercise responses in elite female cyclists at moderate simulated altitude, J APP PHYSL, 89(5), 2000, pp. 1819-1824
The effect of hypoxia on the response to interval exercise was determined i
n eight elite female cyclists during two interval sessions: a sustained 3 x
10-min endurance set (5-min recovery) and a repeat sprint session comprisi
ng three sets of 6 x 15-s sprints (work-to-relief ratios were 1:3, 1:2, and
1:1 for the Ist, 2nd, and 3rd sets, respectively, with 3 min between each
set). During exercise, cyclists selected their maximum power output and bre
athed either atmospheric air (normoxia, 20.93% O-2) or a hypoxic gas mix (h
ypoxia, 17.42% O-2). Power output was lower in hypoxia vs. normoxia through
out the endurance set (244 +/- 18 vs. 226 +/- 17, 234 +/- 18 vs. 221 +/- 25
, and 235 +/- 18 vs. 221 +/- 25 W for Ist, 2nd, and 3rd sets, respectively;
P < 0.05) but was lower only in the latter stages of the second and third
sets of the sprints (452 +/- 56 vs. 429 +/- 49 and 403 +/- 54 vs. 373 +/- 4
3 W, respectively; P < 0.05). Hypoxia lowered blood O-2 saturation during t
he endurance set (92.9 +/- 2.9 vs. 95.4 +/- 1.5%; P < 0.05) but not during
repeat sprints. We conclude that, when elite cyclists select their maximum
exercise intensity, both sustained (10 min) and short-term (15 s) power are
impaired during hypoxia, which simulated moderate (<similar to>2,100 m) al
titude.