Exercise-induced Dehydration Does not Alter Time Trial or Neuromuscular Performance

This study examined the effect of exercise-induced dehydration by similar to 4% body mass loss on 5-km cycling time trial (TT) performance and neuromuscular drive, independent of hyperthermia. 7 active males were dehydrated on 2 occasions, separated by 7 d. Participants remained dehydrated (DEH, -3.8 +/- 0.5%) or were rehydrated (REH, 0.2 +/- 0.6%) over 2 h before completing the TT at 18-25 degrees C, 20-30% relative humidity. Neuromuscular function was determined before dehydration and immediately prior the TT. The TT started at the same core temperature (DEH, 37.3 +/- 0.3 degrees C; REH, 37.0 +/- 0.2 degrees C (P > 0.05). Neither TT performance (DEH, 7.31 +/- 1.5 min; REH, 7.10 +/- 1.3 min (P > 0.05)) or % voluntary activation were affected by dehydration (DEH, 88.7 +/- 6.4 %; REH, 90.6 +/- 6.1 % (P > 0.05)). Quadriceps peak torque was significantly elevated in both trials prior to the TT (P < 0.05), while a 19 % increase in the rate of potentiated peak twitch torque development (P < 0.05) was observed in the DEH trial only. All other neuromuscular measures were similar between trials. Short duration TT performance and neuromuscular function are not reduced by dehydration, independent of hyperthermia.