When is warming-up a bad idea? Not often, but in a particular circumstance when your athletes will exercise in the heat, the opposite strategy might be more appropriate: pre-cooling.
Uckert et al. (2007) examined the effect of three pre-race strategies on endurance performance in the heat. Twenty males participated in the study and were asked to perform a treadmill test to exhaustion following any of the following pre-run preparations: 20min warm-up, 2omin pre-cooling with 0-5C ice-jacket, or no specific preparation. Measures taken during the experiment included heart rate (HR), blood lactate (BLa), skin temperature and core temperature.
The results demonstrate that a pre-cooling strategy v 20min warm-up resulted in a significantly greater endurance performance time. The pre-cooling strategy demonstrated a positive effect on both core and skin temperature which were they key variables in maintaining running time. The authors suggest that warming-up in the heat prior to endurance performance may actually be detrimental. Pre-cooling combined with regular endurance training (LSD and interval) is likely make your athletes perform very well in the heat! Areas suggested for pre-cooling include trunk and neck.