Cognitive and athletic performances in tropical climate: The effect of time of day.

We determined whether the time of day when students exercise in a tropical climate and the environmental conditions in which they attend theory classes (air conditioning vs. tropical climate) have an impact on athletic performance and physiological, psychological and perceptual parameters. Twenty-nine students took part in four experimental sessions consisting of outdoor exercises and theory classes from 7am-1pm, according to a randomized and counterbalanced order. Cognitive and exercise performances, perceptual responses, core temperature and heart rate were assessed in the air-conditioned and tropical climate conditions. Cognitive performance was lower in the tropical vs air-conditioned environment, including lower concentration, higher inattention and lower processing speed during the theory classes. During theory classes in a tropical climate, heart rate and core temperature were higher. Average concentration scores (i.e. mean: 107.0 vs. 234.0), and inattention (i.e. mean: 96.0 vs. 32.5) at end-morning (i.e. 11am-1pm) were negatively affected by tropical climate compared to air conditioning when it was preceded by physical exercise at 9am-11am, but not at 7am-9am. There was a momentary sensation of fatigue, with higher scores at 11am-1 pm than at 7am-9am, in both conditions. Core temperatures were higher during exercise performance at 9am-11 am (38.6°C ±4.9°C) than at 7am-9 am (38.3°C ±5.2°C), but there was no difference for exercise performance, heart rate. Climate conditions must be taken into account for (i) cognitive performance and physiological parameters in tropical climate, and (ii) the time of day for exercise when theory classes take place in late morning and young student-athletes must perform cognitively well.