Cycling in Hot weather – Keep yourself hydrated

When we exercise in hot weather, we sweat more to help us control our body temperature. Our body operates optimally within a narrow temperature range and when our body loses it’s ability to control body temperature, people can feel faint, dizzy and nauseous. These are symptoms of heat stroke. If you are sweating more during the Ring of Kerry, then you need to be able to replace most of the body water that’s lost due to sweating.

However, this isn’t as easy as it sounds.

People sweat at different rates. One person might lose 1kg of body weight during a one hour cycle, another person might lose 2kg.
Taking some simple measurements when you go out for a cycle, you can calculate your individual sweat rate.

http://www.triharder.com/thm_swrate.aspx

You don’t need to replace all fluid losses 100% while you exercise, but it would be advisable to replace 90-95% of the fluid you sweat.
In order to calculate your sweat rate accurately, you should cycle on similar terrain and in similar weather conditions to what you will be cycling in during the Ring of Kerry (but who can predict the weather in Ireland!).

It is also advisable to add electrolytes (e.g. dioralytes) to your drinks to replace electrolyte losses when you sweat. Most commercial sports drinks and gels contain electrolytes. Fruits are also high in electrolytes. Adding electrolytes to drinks or drinking water when you eat food also helps your body to better absorb the fluid you drink.

Be careful of drinking too much fluid when you exercise. Excessive consumption of fluid can lead to hyponatraemia:

https://www.mayoclinic.org/diseases-conditions/hyponatremia/symptoms-causes/syc-20373711 

Calculating your own sweat rate and sticking to your drinking schedule, as well as consuming electrolytes will prevent you from over consumption of fluids leading and the symptoms of hyponatraemia.

Finally, weigh yourself before and after your cycle. Your post cycle weight should be lower than your pre-cycle weight. If it is, multiply the weight difference by 1.5 and this is the amount of fluid you need to consume to rehydrate yourself. If you weigh more after your cycle, this means you probably consumed too much fluid during your cycle.