BACKGROUND: The replacement required of water waste is recognized and established in an international consensus. However, the influence of the replacement in cardiorespiratory parameters, especially when administered during and after physical activity, remains poorly understood. OBJECTIVE: To analyze the effects of fluid replacement in heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), partial oxygen saturation (SpO2) and respiratory rate (f) of the youngsters during and after a long-term exercise. METHODS: 31 individuals (21.55 ± 1.89 years old) performed three visits in the laboratory (48 hours among them), at first an incremental test was applied to determine the load used during subsequent visits. In the last two, called control protocol (CP) and the experimental protocol (EP), the subjects were undergone to a 10 min of supine rest, 90 min of treadmill exercise (60% of VO2peak) and 60 min of supine rest. The difference between the protocols is that in the EP there was the intake isotonic solution and the CP there wasn't hydration. The parameters HR, SBP, DBP, SpO2 and f were measured at the end of the rest, in 30, 60 and 90 minutes of the activity, except the f parameter, and at 1, 3, 5, 7, 10, 20, 30, 40, 50 and 60 minute post-exercise. Student t test or Mann-Whitney, and ANOVA repeated measures or Friedman test followed by post hoc tests, were applied (p < 0.05). RESULTS: the intake isotonic solution provided SBP and DBP maintenance and smaller increment in HR during the exercise; promoted faster return of HR and kept SpO2, SBP (from the 5th minute) and f (from the 30th min) during recovery. CONCLUSION: the hydration protocol influenced the cardiorespiratory parameters for youngsters during and after submaximal physical exercise of constant intensity and long duration.
Aerobic exercise; Rehydration solutions; Heart rate; Blood pressure; Respiratory rate
