Postural Effect on Oxygen Intake and Heart Rate and Sex Difference in It

Abstract

Oxygen intake and heart rate during ten basic postures were measured in 13 young male adults. Significant difference for different postures were more frequently observed for mean heart rate levels than for oxygen intake (Tables 3 & 4). The analysis of covariance for both measurements disclosed that changes in heart rate level were, to a considerable extent, independent from the oxygen intake level (Table 5). The regression equation of heart rate on oxygen intake was calculated without the sum of squares for subject factor, and then the heart rate for each posture was adjusted by the differences in oxygen intake along the regression equation (Table 6). Adjusted heart rate for each posture was shown to have high rank correlation with the projected height of the postures, though the oxygen intake showed no significant correlation with the latter (Table 7). It was indicated that there was sex difference in heart rate level in general (Table 2) and especially in lying posture (Table S). This difference in heart rate between male and female was enlarged if the heart rate was adjusted by the difference in oxygen intake in each posture (Table 9). Significant differences were indicated in the elevation (Table 10) and slope (Table 11) of the regression lines of heart rate on oxygen intake between male and female adults. These results suggest that the heart rate plays more important role in the oxygen transportation during keeping postures for females than for males.