An evaluation of the concept of living at moderate altitude and training at sea level

Despite equivocal findings about the benefit of altitude training, current theory dictates that the best approach is to spend several weeks living at greater than or equal to 2500 m but training near sea level. This paper summarizes six studies in which we used simulated altitude (normobaric hypoxia) to examine: (i) the assumption that moderate hypoxia compromises training intensity (two studies); and (ii) the nature of physiological adaptations to sleeping in moderate hypoxia (four studies). When submaximal exercise was >55% of sea level maximum oxygen uptake ((V) over dot o(2max)), 1800 m simulated altitude significantly increased heart rate, blood lactate and perceived exertion of skiers. In addition, cyclists self-selected lower workloads during high-intensity exercise in hypoxia (2100 m) than in normoxia, Consequently, our findings partially confirm the rationale for 'living high, training low'. In the remaining four studies, serum erythropoietin increased 80% in the early stages of hypoxic exposure, but the reticulocyte response did not significantly exceed that of control subjects. There was no significant increase in haemoglobin mass (Hb(mass)) and (V) over dot o(2max) tended to decrease. Performance in exercise tasks lasting similar to 4 min showed a non-significant trend toward improvement (1.0 +/- 0.4% vs. 0.1 +/- 0.4% for a control group; P = 0.13 for group X time interaction). We conclude that sleeping in moderate hypoxia (2650-3000 m) for up to 23 days may offer practical benefit to elite athletes, but that any effect is not likely due to increased Hb(mass) or (V) over dot o(2max). (C) 2001 Elsevier Science Inc. All rights reserved.