Heat Illness

Exercise and Environmental factors are the most common causes of heat related illness. However several other factors can play a part including medical illness (eg. infection), drugs/medication, dehydration, being overweight, lack of acclimatization and the extremities of age.  In race situations many environmental factors such as heat, wind, and cloud cover are simply unavoidable if you choose to exercise!

Preparation/Prevention

1. Acclimatization:  Proper acclimatization takes at least 2 weeks and aims to increase the amount of sweating (at a lower temperature) and reduce salt loss from the kidneys/urine.  This can be achieved by training under similar conditions to your planned adventure.  It is important to get some respite from the heat for/during recovery. 

2. Avoid Dehydration:  Hydration in endurance pursuits is a separate topic in itself. Briefly however it is important to note that both dehydration and overhydration (www.overhydration.org) can occur. Avoid ‘Blanket’ drinking/hydration guidelines that advise to drink x mls per hour before/during/after exercise as there are many variables that make these unreliable.  Know through experience how much fluid you may need in certain conditions.  Weigh yourself before and after training to estimate fluid loss/gain.  It is important to note that whilst there is a correlation between >3% dehydration and a rise in core body temperature (CBT) the biggest determinant in CBT is effort/workload.  Needless to say the ingestion of cold fluids can aid cooling.

3. Adequate clothing (light, loose fitting, breathable) and sun protection is vital

4. Pre-cooling: some high performance athletes propose pre-cooling before an event eg. cold showers, pools, slushies.