抄録
After training at high altitude, the effect on an individual endurance performance is varied. The purpose of this study was to investigate the effect of artificially increased dead space on the value of maximal oxygen uptake. Healthy male students sat for 5 minutes at rest and performed the graded sub-maximal exercise testing for 14 minutes using a treadmill including resting for 2 minutes twice, with or without artificially dead space of 820ml. The values of maximal oxygen uptake were estimated using the heart rate - oxygen uptake relation with the heart rate at 200 beats/min. The estimated maximal oxygen uptake with artificially increased dead space ranged widely from 87 to 56 percent of the maximal oxygen uptake without dead space as a control. These decreased values with dead space of 820 ml were equivalent to the reported values that were obtained in the environment at an altitude of about 2,550 - 5,000 meters. The observed percent of maximal oxygen uptake correlated with the percent of oxygen uptake with dead space/ control at the heart rate of more than 165 beats/min. The percent of maximal oxygen uptake correlated negatively with the percent of expiratory gas volume at the oxygen uptake of more than 1.5 l/min, in particular from the lower oxygen uptake levels. Therefore, the individual decline in oxygen uptake with dead space is caused by the individual decrease in ventilatory efficiency, and this method can be useful to determine an individual's capacity to adapt to high altitudes. [Jpn J Physiol 54 Suppl:S238 (2004)]
