Treadmill Time-Trial Performance Of Unacclimatized Lowlanders Following Rapid Ascent To 3500 M Or 4050 M

Our group recently published a mathematical model depicting the relationship of the change in cycle ergometer time-trial (TT) performance duration as a function of increasing elevation for unacclimatized lowlanders within their first 8 hrs of exposure to elevations up to 4300 m (Beidleman et al., Med Sci Sports Exerc 2015). Whether the model is generalizable for TT performance assessments using a different mode of exercise (i.e., treadmill) and within the first 48 hrs of exposure is unknown. PURPOSE: Determine if the changes in treadmill TT performance durations of unacclimatized individuals measured both at sea level (SL, 50 m) and either 3500 m or 4050 m can be estimated accurately using the published cycle ergometer TT performance model. METHODS: Forty-three healthy volunteers (35 men and 8 women; mean ± SD; 22 ± 4 yrs, 74.5 ± 12.5 kg; 49.8± 7.3 ml·kg-1·min-1) completed a treadmill TT lasting 8.0-11.2 km both at SL and within the first 48 hr of arrival at either 3500 m (n = 16) or 4050 m (n = 27). The % increase in treadmill TT duration from SL to each elevation was the outcome variable which was, in turn, compared to the results estimated at the identical elevations using the cycle TT model. RESULTS: The % increase in duration for the treadmill TT versus that estimated using the cycle TT model did not differ either at 3500 m (26.7 ± 14.8% versus 28.4 ± 6.9%, p = 0.69) or 4050 m (44.1 ± 17.5% versus 46.8 ± 1.6%, p = 0.42). CONCLUSION: The findings indicate that our published cycle ergometer model accurately estimates % changes for treadmill TT performance of unacclimatized SL residents during their first 48 hrs of exposure to altitudes of 3500 m and 4050 m. Further, the lack of significant difference between the treadmill and cycle TT performance outcomes at these two elevations suggest that the published predictive model can be applied to treadmill exercise. Disclaimer: Author’s views are not official U.S. Army or DoD policy.