EFFECT OF FLUID INTAKE ON PLASMA VOLUME, OSMOLALITY, BODY TEMPERATURE AND PERFORMANCE DURING SWIMMING TRAINING 764

In this study, we examined the effect of fluid intake on plasma volume, osmolality, body temperature and performance during intense swimming training. Eight male college swimmers gave informed consent documents before participating in this study. Their age was 22.8 ± 1.0 yr, body weight was 66.72 ± 1.63 kg and standing height was 171.7 ± 0.7 cm. The subjects did a set of 20 repeated 50 m swims on a 1 minute interval in two fluid intake conditions (ad libitum, no fluid intake). Blood samples, body temperature (oral temperature), heart rate, RPE, and body weight were measured before and after interval training. The mean water temperature during training was 29.95 ± 0.05 °C. Heart rate and RPE after interval training at ad libitum was 187.5 ± 3.6 bpm, 16.2 ± 0.5 and those at no fluid intake was 188.3 ± 3.1 bpm, 17.0 ± 0.6. Plasma volume decreased by 9.4 ± 1.3 and 7.5 ± 1.7%, and plasma osmolality increased by 5.1 ± 1.3 and 5.9 ± 1.9 mosmol/kgH2O at ad libitum and no fluid intake, respectively. The difference of body temperature before and after training was 0.63 ± 0.15, 0.77 ± 0.11 °C, the sweat loss was 0.38 ± 0.06, 0.37 ± 0.04 kg, and fluid intake ratio(fluid intake / sweat loss × 100) was 26.7 ± 4.08, 0% at ad libitum and no fluid intake, respectively. The mean swimming time was significantly difference between ad libitum (35.10 ± 0.48 sec) and no fluid intake (35.35 ± 0.46 sec). In conclusion, fluid intake during interval swimming training may keep performance high and suppress body temperature, though there is no significant differences in plasma volume and osmolality changes between two fluid intake strategies.