ABSTRACT
The aim of this studv was to clarify the effects of water immersion on the cardiovascular recovery process following submaximal steady state exercise on land. Seven male subjects (23 yrs old) underwent experiments under four separate conditions on separate days (15 minutes of cycling exercise at 50% and 80% maximal oxygen consumption followed by 16 minutes of recovery in a sitting position in water and out of water) . Concerning conditions in water, mean water temperature was 29.4 degrees, and the immersion level was set at xiphoid. Mean room temperature in out of water conditions, and during all conditions of exercise, was 24.4 degrees. Oxygen consumption (VO<SUB>2</SUB>), heart rate (HR) and blood pressure (systolic: SBP, diastolic: DBP) were measured under each condi tion. Mean blood pressure was calculated from SBP and DBP (MBP=1/3× ( SBP-DBP) +DBP) . Stroke volume (SV) was measured by Doppler echocardiography, and then cardiac output (CO=SV×HR), total peripheral resistance (TPR=NIBP/CO) and arteriaVmixed venous oxygen difference (a-v O<SUB>2</SUB>diff=VO<SUB>2</SUB>/CO) were calculated. In comparison with the same exercise intensity condition, there were no significant differences between recovery processes of VO<SUB>2</SUB>, HR, SBP, DBP and MBP in and out of water. SV and CO were significantly higher (p<0.05) during the recovery process in water than out of water (SV: at 50 and 80% maximal oxygen consumption conditions, CO: at 80% condition) . The TPR and a-v O<SUB>2</SUB>diff were significantly lower (p<0.05) during the recovery process in water than out of water at 80% oxygen consumption condition. These results indicate that water immersion facilitates circulating blood volume during the recovery process without increasing blood pressure, especially during recovery after high intensity exercise. Therefore, we suggest that increased left ventricular preload with immersion would be an important factor in cardiovascular regulation not only at rest but also during recovery after exercise.
ABSTRACT
The purpose of this study was to determine the physiological responses, stroke rate and stroke length of front crawl leg kick and arm stroke of age-group and college swimmers and to elucidate the characteristics of male age-group swimmers, which have not been highlighted adequately. The subjects were ten 11.8-to 12.4-year-old well-trained male elementary school swimmers (group E) and nine 20.1-to 21.1-year-old well-trained male college swimmers (group C) . All the subjects were categorized into similar swimming levels for their ages. All the experiments were performed in a swimming flume (AQUAGYM made by IHI) . The water velocities during leg kicking and arm stroking were 60 and 70%, respectively, of the maximal velocity at maximal oxygen uptake (Vmax) . The oxygen uptake (VO<SUB>2</SUB>), heart rate (HR), pulmonary ventilation (V<SUB>E</SUB>), tidal volume (TV), respiratory rate (RR) and blood lactate (BL) level of each group were significantly higher during leg kicking than arm stroking at both velocities. VO2, V<SUB>E</SUB>; and TV were significantly higher in group C than group E during leg kicking and arm stroking at both velocities, but HR, RR and BL did not differ significantly. The leg kick to arm stroke VO<SUB>2</SUB> ratio at 70% Vmax was significantly higher in group E than group C. The stroke rate at the same velocity was significantly lower and the stroke length was significantly higher in group C than group E, but the kick rate and length did not differ significantly. VO<SUB>2</SUB>·SR<SUP>-1</SUP> and VO<SUB>2</SUB> KR<SUP>-1</SUP> at both velocities were significantly higher in group C than group E. VO<SUB>2</SUB> Wt<SUP>-1</SUP> SR<SUP>-1</SUP> at 70% Vmax was significantly higher in group C than group E, but VO<SUB>2</SUB> Wt<SUP>-1</SUP> KR<SUP>-1</SUP> at both velocities was significantly lower in group C than group E. These results clarified the differences between group E and group C, which must be considered carefully when designing a training program for age-group swimmers.