Two days of staging at moderate altitude results in similar time‐trial performance impairments at 4300m compared to direct ascent and stay for two days at 4300m

Abstract

Staging at moderate altitude or direct ascent and stay at high altitude (HA) are strategies used to reduce time‐trial (TT) performance impairments at HA. To determine whether 2 days (d) of staging at 2500m or 3000m prior to ascent is as effective as 2 d of continuous living at 4300m, we measured TT performance following 2 h of exposure to 4300m in young fit men. Two groups of unacclimatized men staged at either 2500m (n=12) or 3000m (n=7) for 2 d prior to ascent to 4300m were compared to a 3rd group that directly ascended and lived for 2 d at 4300m (n=7) prior to testing. Acute mountain sickness (AMS‐C) was assessed prior to performing an all out 5‐mile treadmill TT at sea level (SL) and HA. Heart rate (HR), arterial oxygen concentration (SaO2), and rating of perceived exertion (RPE) were recorded every 5 min during the TT and the mean value was calculated. From SL to ALT, the %increase in TT‐completion time was similar (P>;0.05) in the 2500 m (44±27%), 3000 m (39±27%) and direct ascent group (58±28%). There was no difference (P>;0.05) in the mean exercise HR, SaO2, or RPE between groups at SL or HA. AMS prevalence was lower (P<0.05) in the staged groups (both 0%) than the direct ascent group (29%). These results suggest that 2 d of staging at moderate altitude reduces AMS but results in similar TT performance impairments as direct ascent and stay for 2 d at 4300 m. Funding: USAMRMC. Authors’ views; not official US Army or DoD policy.