Comparison of equilibrium and extrapolation methods of CO2 rebreathing for determining the mixed venous CO2 pressure / 体力科学

The purpose of this study was to compare two methods of CO<SUB>2</SUB> rebreathing-equilibrium method (Collier, 1965) and extrapolation method (Defares, 1958) -for determining the mixed venous CO<SUB>2</SUB> pressure (PvCO<SUB>2</SUB>) during exercise. Following a sitting rest for 5 min, five healthy males performed upright bicycle ergometer exercises with work rate of 100 and 150W for 5 min. During both at rest and in exercise, PvCO<SUB>2</SUB> was measured twice to evaluate the reproducibility of both methods. The equilibrium method was performed according to that by Jones & Campbell (1982) . In the extrapolation method, instead of using the graphical analysis described by Klauaen (1965), PvCO<SUB>2</SUB> was directly calculated by applying the modified exponential equation (Defares, 1958) . In the duplicate tests, coefficient of variation was lower while correlation coefficient was higher, with increasing work rate in both methods. It was noted that these tendencies were more pronounced in the extrapolation method than in the equilibrium method. It was concluded that in contrast to the results of Auchincloss et al. (1980), the extrapolation method was more reproducible than the equilibrium method.

Altitude training for improving swimming performance at sea level / 体力科学

The present study was designed to investigate the effects of low altitude training on swimming performance with setting the same duration (3-wk) and the same level of altitude (2, 300m) . Eight male (Gm<SUB>1</SUB>) swimmers aged 13 to 19 years and four male (Gm<SUB>2</SUB>) and eight female (Gf<SUB>2</SUB>) swimmers aged 13 to 18 years sent to Mexico City, and they conducted swimming work outs. All of them were top Japanese swimmers of various events. They repeated the swimming training twice a day continuously for four days with one day rest. Hemoglobin concentration (Hb), red blood cell count (RBC) and hematocrit (Hct) were determined before, during and after the altitude training several times. The values of Hb, RBC and Hct of all three groups increased significantly from before training to after training except Hb in Gm<SUB>1</SUB>. On the other hand, these three variables did not necessarily increase during the altitude training. Gm<SUB>1</SUB> and Gf<SUB>2</SUB> tended to increase Hb and RBC during the training. As for swimming performance at sea level, the individual best swimming records were improved significantly in 200m events, but not in 100m events in Gm<SUB>1</SUB>. Therefore, it may be concluded that 3-wk altitude (2, 300m) training possibly improve swimming performance in the events equal to or longer than 200m at sea level.