'Living high-training low': Effect of moderate-altitude acclimatization with low-altitude training on performance

The principal objective of this study was to test the hypothesis that acclimatization to moderate altitude (2,500 m) plus training at low altitude (1,250 m), 'living high-training low,' improves sea-level performance in well-trained runners more than an equivalent sea-level or altitude control. Thirty-nine competitive runners (27 men, 12 women) completed 1) a 2-wk lead- in phase, followed by 2) 4 wk of supervised training at sea level; and 3) 4 wk of field training camp randomized to three groups: 'high-low' (n = 13), living at moderate altitude (2,500 m) and training at low altitude (1,250 m); 'high-high' (n = 13), living and training at moderate altitude (2,500 m); or 'low-low' (n = 13), living and training in a mountain environment at sea level (150 m). A 5,000-m time trial was the primary measure of performance; laboratory outcomes included maximal O₂ uptake (V̇O(2max)), anaerobic capacity (accumulated O₂ deficit), maximal steady state (MSS; ventilatory threshold), running economy, velocity at V̇O(2max), and blood compartment volumes. Both altitude groups significantly increased V̇O(2max) (5%) in direct proportion to an increase in red cell mass volume (9%; r = 0.37, P < 0.05), neither of which changed in the control. Five-kilometer time was improved by the field training camp only in the high-low group (13.4 ± 10 s), in direct proportion to the increase in V̇O(2max) (r = 0.65, P < 0.01). Velocity at V̇O(2max) and MSS also improved only in the high-low group. Four weeks of living high-training low improves sea-level running performance in trained runners due to altitude acclimatization (increase in red cell mass volume and V̇O(2max)) and maintenance of sea- level training velocities, most likely accounting for the increase in velocity at V̇O(2max) and MSS.