Recovery of voluntary and evoked muscle performance following intermittent-sprint exercise in the heat.
OBJECTIVE
This study investigated the effects of hot conditions on the acute recovery of voluntary and evoked muscle performance and physiological responses following intermittent exercise.


METHODS
Seven youth male and six female team-sport athletes performed two sessions separated by 7 d, involving a 30-min exercise protocol and 60-min passive recovery in either 22 degrees C or 33 degrees C and 40% relative humidity. The exercise protocol involved a 20-s maximal sprint every 5 min, separated by constant-intensity exercise at 100 W on a cycle ergometer. Maximal voluntary contraction (MVC) and a resting evoked twitch (Pf) of the right knee extensors were assessed before and immediately following exercise and again 15, 30, and 60 min postexercise, and capillary blood was obtained at the same time points to measure lactate, pH, and HCO3. During and following exercise, core temperature, heart rate and rating of perceived exertion (RPE) were also measured.


RESULTS
No differences (P=0.73 to 0.95) in peak power during repeated sprints were present between conditions. Postexercise MVC was reduced (P<.05) in both conditions and a moderate effect size (d=0.60) indicated a slower percentage MVC recovered by 60 min in the heat (83+/-10 vs 74+/-11% recovered). Both heart rate and core temperature were significantly higher (P<.05) during recovery in the heat. Capillary blood values did not differ between conditions at any time point, whereas sessional RPE was higher 60 min postexercise in the heat.


CONCLUSIONS
The current data suggests that passive recovery in warm temperatures not only delays cardiovascular and thermal recovery, but may also slow the recovery of MVC and RPE.
Duffield
Rob
R
School of Human Movement Studies, Charles Sturt University, Bathurst, NSW, Australia.
King
Monique
M
Skein
Melissa
M
D000293:Adolescent; D054874:Athletic Performance; D001639:Bicarbonates / Q000097:blood; D001831:Body Temperature; D004558:Electric Stimulation; D005260:Female; D006339:Heart Rate; D006358:Hot Temperature; D006801:Humans; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000097:blood; D008297:Male; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000294:innervation / Q000502:physiology*; D010465:Perception; D005082:Physical Exertion; D020127:Recovery of Function; D012420:Running; D013647:Task Performance and Analysis; D013997:Time Factors; D014836:Volition; D055815:Young Adult
D001639:Bicarbonates; D019344:Lactic Acid