Abstract
We have reported an individual difference in exercise performance induced by artificially added dead space as a simulation method at high altitudes. The purpose of this study was to summarize the characteristics of circulation and respiration during repeated exercise testing with or without dead space. Healthy male students performed alternatively the graded sub-maximal exercise four times with or without additional horse, the volume of which was 820 ml to respiratory mask. The graded exercise testing using treadmill was started after interval for 30 minutes. The values of estimated maximal oxygen uptake with dead space were revision of wide range from 96 to 56 (mean: 80) 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 at an altitude of about 1,180–5,000 (mean: 3,340) meters. The observed individual percent of maximal oxygen uptake correlated negatively with the percent of ventilatory equivalent (expiratory gas volume / 100 mlO2) with dead space/ control at above the low intensity of exercise, except that at rest. The individual regression line of heart rate and oxygen uptake shifted to the right by the effects of added dead space and repeated exercise testing. However, each value in percent of ventilatory equivalent was fixed with or without dead space, and it was not affected by repeated exercise testing. Therefore, it is necessary to analyze the ventiratory efficiency during exercise at high altitudes. [Jpn J Physiol 55 Suppl:S224 (2005)]
