Prediction of physiological responses and performance at altitude using the 6-minute walk test in normoxia and hypoxia

The 6-minute walk test (6MWT) is a reliable and valid tool for determining an individual’s functional capacity, and has been used to predict summit success. The primary aim of the study was to evaluate whether a 6MWT in normobaric hypoxia could predict physiological responses and exercise performance at altitude. The secondary aim was to determine construct validity of the 6MWT for monitoring acclimatization to 3400m (Cuzco, Peru). Methods Twenty-nine participants performed six 6MWTs in four conditions: normoxic outdoor (NO), normoxic treadmill (NT), and hypoxic treadmill (HT) were each performed once, and hypoxic outdoor (HO) was performed three times, at 42 hours (HO1), 138 hours (HO2), and 210 hours (HO3) after arrival at Cuzco. Results. One-way analysis of variance revealed no difference (P > .05) between NO and HO1 for 6MWT distance. HT and HO protocols were comparable for the measurement of delta heart rate (HR) and posttest peripheral oxygen saturation (%SpO2; P > .05). Acclimatization was evidenced by reductions (P < .05) in resting HR and respiratory rate (RR) between HO1, HO2, and HO3, and preservation of SpO2 between HO1 and HO2. Postexercise HR and RR were not different (P > .05) with acclimatization. The duration to ascend to 4215 m on a trek was moderately correlated (P < .05) to HR during the trek Conclusions. The 6MWT is a simple, time-efficient tool for predicting physiological responses to simulated and actual altitude, which are comparable. The 6MWT is effective at monitoring elements of acclimatization to moderate altitude. Conclusions. The 6MWT is a simple, time-efficient tool for predicting physiological responses to simulated and actual altitude, which are comparable. The 6MWT is effective at monitoring elements of acclimatization to moderate altitude.