Partial heat acclimation in cricketers using a 4-day high intensity cycling protocol.
Cricketers are often required to play in hot/humid environments with little time for heat adaptation.


OBJECTIVE
We examined the effect of a short 4-d hot/humid acclimation program on classical physiological indicators of heat acclimation.


METHODS
Male club cricketers were randomly assigned into heat acclimation (ACC, n = 6) or control (CON, n = 6) groups, and 30 min treadmill trials (10 km/h, approx. 30 ± 1.0°C, approx. 65 ± 6% RH) were conducted at baseline and postacclimation. The ACC group completed four high intensity (30-45 min) acclimation sessions on consecutive days at approx. 30°C and approx. 60% RH using a cycle ergometer. The CON group completed matched cycle training in moderate conditions (approx. 20°C, approx. 60% RH). Physiological measures during each treadmill trial included heart rate; core and skin temperatures; sweat Na+, K+ and Cl- electrolyte concentrations; and sweat rate.


RESULTS
After the 4-d intervention, the ACC group had a moderate decrease of -11 (3 to -24 beats/min; mean and 90% CI) in the 30 min heart rate, and moderate to large reductions in electrolyte concentrations: Na+ -18% (-4 to -31%), K+ -15% (0 to -27%), Cl- -22% (-9 to -33%). Both ACC and CON groups had only trivial changes in core and skin temperatures and sweat rate. After the intervention, both groups perceived they were more comfortable exercising in the heat. The 4-d heat intervention had no detrimental effect on performance.


CONCLUSIONS
Four 30-45 min high intensity cycle sessions in hot/humid conditions elicited partial heat acclimation. For full heat acclimation a more intensive and extensive (and modality-specific) acclimation intervention is needed for cricket players.
Department of Physiology, Australian Institute of Sport, Australia.
Carl J
CJ
Petersen
Marc R
MR
Portus
David B
DB
Pyne
Brian T
BT
Dawson
Matthew N
MN
Cramer
Aaron D
AD
Kellett
D000222:Adaptation, Physiological; D000328:Adult; D056352:Athletes; D001831:Body Temperature / Q000502:physiology; D002712:Chlorides / Q000378:metabolism; D016552:Ergometry; D006339:Heart Rate / Q000502:physiology; D006358:Hot Temperature; D006801:Humans; D006813:Humidity; D008297:Male; D011188:Potassium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D013542:Sweat / Q000378:metabolism
D002712:Chlorides; D012964:Sodium; D011188:Potassium