Effect of dehydration during a prolonged submaximal exercise, on lactate, cortisol and glucose concentration

Abstract

Objetive: To evaluate, in nine long distance runners, the effects of dehydration during a submaximal (80% of the maximal physical work capacity -PWCmax-) and prolonged exercise (90 minutes), on serum concentration of lactate and its relation with cortisol and glucose.

Methods: After a ten-minute warm-up on a treadmill, 1% grade and at 55% of PWCmax, followed by 90 min test in six stages, at 80% of PWCmax, there was a final 90 min passive recovery period. No water was replenished during the DH procedure (dehydration); during the RH procedure (rehydration) 51% of the body weight lost during the DH procedure was replaced.

Results: In dehydrated runners increments were observed, with respect to the basal values, in lactate serum concentration, at the end of the exercise (minute 90); in plasmatic cortisol concentration at the end of the exercise (minutes 75 and 90) and in the first hour of the recovery period; and in glucose plasmatic concentration throughout the procedure. With partial water replenishment lactate increment became significant during almost all stages of the exercise; cortisol increment was avoided; glucose increment was lower during the exercise and avoided during recovery.

Conclusion: During a submaximal and prolonged exercise performed by long distance runners, under