Influence of diuretic-induced dehydration on competitive running performance

Abstract

A diuretic drug (40 mg of furosemide) was utilized to study the effects of dehydration (D) on competitive running performance, without prior thermal or exercise stress. Eight men competed in randomized races of 1500, 5000 and 10,000 m, while normally hydrated (H) and with mean plasma volume reductions of 9.9, 12.3 and 9.9%, respectively. As a result of the reduced body water (change in body wt = -1.9, -1.6 and -2.1%), mean outdoor performance times on a running track increased 0.16 min, 1.31 min (P < 0.05) and 2.62 min (P < 0.05) in the 1500 m, 5000 m and 10,000 m trials. Running performance decrements due to dehydration were more strongly correlated with changes in body wt (r = -0.79, -0.65, and -0.40) than with urine volume or plasma volume differences. In addition, subjects were studied during submaximal and maximal treadmill exercise while H and D (mean change in plasma volume = -7.1%). Neither submaximal nor maximal O2 uptake was significantly altered (P > 0.05) as a consequence of D. Mean treadmill run time to volitional exhaustion was reduced by 41.4 s (P < 0.05) during the D treadmill trial. Competitive performance in trials of long duration (5000 and 10,000 m) apparently was affected to a greater extent by D than the shorter 1500 m event, even though submaximal and maximal O2 uptake was not altered.