Short duration heat acclimation in Australian football players

This study examined if five sessions of short duration (27 min),high intensity,interval training (hiit) in the heat over a nine day period would induce heat acclimation in australian football (af) players. fourteen professional af players were matched for vo2peak (ml∙kg-1∙min-1) and randomly allocated into either a heat acclimation (acc) (n = 7) or control (con) group (n = 7). the acc completed five cycle ergometer hiit sessions within a nine day period on a cycle ergometer in the heat (38.7 ± 0.5 °c; 34.4 ± 1.3 % rh),whereas con trained in thermo-neutral conditions (22.3 ± 0.2 °c; 35.8 ± 0. % rh). four days prior and two days post hiit participants undertook a 30 min constant load cycling test at 60% v̇o2peak in the heat (37.9 ± 0.1 °c; 28.5 ± 0.7 % rh) during which vo2,blood lactate concentration ([lac-]),heart rate (hr),rating of perceived exertion (rpe),thermal comfort,core and skin temperatures were measured. heat acclimation resulted in reduced rpe,thermal comfort and [lac-] (all p < 0.05) during the submaximal exercise test in the heat. heart rate was lower (p = 0.007) after hiit,in both groups. heat acclimation did not influence any other measured variables. in conclusion,five short duration hiit sessions in hot dry conditions induced limited heat acclimation responses in af players during the in-season competition phase. in practice,the heat acclimation protocol can be implemented in a professional team environment; however the physiological adaptations result-ing from such a protocol were limited. © journal of sports science and medicine