The influence of cardiorespiratory fitness on the decrement in maximal aerobic power at high altitude

Summary

There are conflicting reports in the literature which imply that the decrement in maximal aerobic power experienced by a sea-level (SL) resident sojourning at high altitude (HA) is either smaller or larger for the more aerobically “fit” person. In the present study, data collected during several investigations conducted at an altitude of 4300 m were analyzed to determine if the level of aerobic fitness influenced the decrement in maximal oxygen uptake $\dot V_{O_{2\max } }$ at HA. The $\dot V_{O_{2\max } }$ of 51 male SL residents was measured at an altitude of 50 m and again at 4300 m. The subjects' ages, heights, and weights (mean ± SE) were 22±1 yr, 177±7 cm and 78±2kg, respectively. The subjects' $\dot V_{O_{2\max } }$ ranged from 36 to 60 ml·kg⁻¹·min⁻¹ (mean ± SE=48±1) and the individual values were normally distributed within this range. Likewise, the decrement in $\dot V_{O_{2\max } }$ at HA was normally distributed from 3 ml·kg⁻¹·min⁻¹ (9% $\dot V_{O_{2\max } }$ at SL) to 29 ml·kg⁻¹·min⁻¹ (54% $\dot V_{O_{2\max } }$ at SL), and averaged 13±1 ml·kg⁻¹·min⁻¹ (27±1% $\dot V_{O_{2\max } }$ at SL). The linear correlation coefficient between aerobic fitness and the magnitude of the decrement in $\dot V_{O_{2\max } }$ at HA expressed in absolute terms was r=0.56, or expressed as % $\dot V_{O_{2\max } }$ at SL was r=0.30; both were statistically significant (p<0.05). Therefore, only 31 and 9%, respectively, of the variability in the decrement at HA could be attributed to the $\dot V_{O_{2\max } }$ at SL. Thus, while the more aerobically fit individuals do tend to suffer a larger decrement in maximal aerobic power at altitude, the level of aerobic fitness per se accounts for a relatively small amount of the variability between individuals in this decrement.