Greater maximal O2 uptakes and vital capacities in Tibetan than Han residents of Lhasa.

Maximal O2 uptake provides an index of the integrated functioning of the O2 transport system. Whether lifelong high altitude residents have greater maximal exercise capacities than acclimatized newcomers is of interest for determining whether years to generations of high altitude exposure influence maximal O2 uptake and, if so, what components of O2 transport are involved. We studied 16 Tibetan lifelong residents of Lhasa, Tibet, China (3658 m) and 20 Han ("Chinese") 8 +/- 1 year residents of the same altitude who were matched for age, height, weight and lack of exercise training. At maximal effort, the Tibetans compared to the Hans had greater O2 uptakes (51 +/- 1 vs 46 +/- 1 ml STPD.min-1.(kg bw)-1, P less than 0.05), exercise workloads (177 +/- 5 vs 155 +/- 6 watts, P less than 0.05), minute ventilations (149 +/- 6 vs 126 +/- 4 IBTPS/min, P less than 0.01) and O2 pulse (15.2 +/- 0.4 vs 13.3 +/- 0.5 ml O2 consumption/heart beat, P less than 0.05). Equally high heart rates were present at maximal effort (191 +/- 3 vs 187 +/- 3 beats/min, P = NS), supporting the likelihood that true maxima were achieved in both groups. The greater minute ventilation in the Tibetans resulted from greater tidal volume and the greater maximal tidal volume correlated positively with the resting vital capacity. We concluded that the Tibetans achieved a higher maximal O2 uptake than the Hans, implying an increased capacity for O2 transport to the working muscle.