The effect of rapid dehydration on repeated bouts of short-term, high-intensity cycling exercise in college wrestlers

Abstract

This study examined the effects of acute dehydration on repeated bouts of anaerobic cycling exercise. Eight college wrestlers performed 2 cycle ergometer trials before (hydrated, H) and 48 hrs after dehydration (D) via exercise, fluid restriction, and heat exposure. The trials consisted of a 4 min warm-up followed by 5, 10 s maximal bouts interspersed with 20 s rest intervals. The ergometer was preloaded with .1 kg/kg of H bodyweight. Peak power (PP,W), average power (AP,W), time to peak power (TTPP,s), power fatigue rate (PFR,W/s), and power fatigue index (PFI,%) were recorded by an integrated microcomputer. Pretrial plasma osmolality (PO), HTC, plasma electrolytes, and caloric intake (Kcal) were also measured. The wrestlers lost 4.5±1.0% (X±SD) bodyweight from H to D trials which increased PO and HTC (p<.01). There was a decline in plasma [K+] (p<.05) and no change in Kcal. PP values for H bouts 1-5 were 1004±54, 918±47, 809446, 727438, and 681±40 and for D bouts 1-5 were 937±52, 836±46, 766±40, 702±41, and 706±32 (X±SEM). AP results were similar to PP and thus not shown. There were no differences in H and D trials for TTPP, PFR, and PFI. After dehydration PP and AP were reduced during bouts 1-3 (p<.05) and appear to level in bouts 4 and 5 coinciding with H PP and AP. These results suggest that rapid dehydration by wrestlers causes a decrease in PP and AP production during initial bouts of repeated anaerobic exercise. With the onset of fatigue in later bouts PP and AP are unaffected.