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 al titude (1,250 m), ''living high-training low,'' improves sea-level per formance in well-trained runners more than an equivalent sea-level or altitude control. Thirty-nine competitive runners (27 men, 12 women) c ompleted 1) a 2-wk lead-in phase, followed by 2) 4 wk of supervised tr aining at sea level; and 3) 4 wk of field training camp randomized to three groups: ''high-low'' (n = 13), living at moderate altitude (2,50 0 m) and training at low altitude (1,250 m); ''high-high'' (n = 13), l iving 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; labora tory outcomes included maximal O-2 uptake ((V) over dot O-2 max), anae robic capacity (accumulated O-2 deficit), maximal steady state (MSS; v entilatory threshold), running economy, velocity at (V) over dot O-2 m ax and blood compartment volumes. Both altitude groups significantly i ncreased (V) over dot O-2 max (5%) in direct proportion to an increase in red cell mass volume (9%; r = 0.37, P < 0.05), neither of which ch anged in the control. Five-kilometer time was improved by the field tr aining camp only in the high-low group (13.4 +/- 10 s), in direct prop ortion to the increase in (V) over dot O-2 max (r = 0.65, P < 0.01). V elocity at (V) over dot O-2 max 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 (V) over dot O-2 max) and maint enance of sea-level training velocities, most likely accounting for th e increase in velocity at (V) over dot O-2 max and MSS.