Beginning a workout fully hydrated can delay dehydration during exercise, maintain exercise performance and decrease the risk of heat-related illnesses.
Pre-exercise fluid intake can enhance your ability to control body temperature and increase plasma volume to maintain cardiac output. You should drink enough fluids before exercising in the heat to begin every workout fully hydrated, and you should continue to drink during workouts longer than 1 hour. A good indicator of your hydration levels is urine colour. The lighter the urine colour, the better the level of hydration.
What should you drink?
Before exercise: Drink 500ml 2 hours before exercise.
During exercise: Drink about 200ml every 15-20 minutes, aiming to match fluid intake to sweat loss. Maintain 400-600ml of fluid in the stomach to optimize gastric emptying.
After exercise: Drink 1 litre per kilogram of weight lost during your workout
Sodium intake is necessary only if exercise lasts more than 60 minutes or if you have a sodium deficiency. Before, during and after exercise, consume 0.5-0.7 gram per litre of fluid.
Chronically exposing yourself to a hot and humid environment stimulates adaptions that lessen stress on your body. Cardiovascular adaptions to exercising in the heat are nearly complete within 3-6 days. Full acclimatisation becomes complete after 2 weeks as the increased sweating response catches up to the other adaptions. Therefore, take 2 weeks of slowly introducing yourself to the heat to be fully acclimatised and prepare for prolonged continuous exercise.