Whether you are a seasoned endurance athlete or taking on your first endurance event, having a personalised hydration strategy is crucial for optimal performance in both training and racing. When we sweat, we lose both fluid and electrolytes and this can have a negative impact on performance if the losses are excessive. For, example our exercise performance can be reduced if we lose 2-3% or more body weight through sweat(1, 2). Sweat rates during exercise can range from 0.3-2.4 L/h, depending on a number of factors, including, but not limited to: environmental conditions, exercise intensity & duration and equipment(1, 2).
Measuring Your Sweat Rate
The first stage in planning fluid intake around performance is to understand your personal sweat rate and hydration status. A combination of body weight changes during exercise and urine colour are simple tools that can be used to determine these factors.
The following calculation will provide a guide as to your personal sweat rate during exercise, in litres of fluid lost per hour; where body weight is measured in kilograms, fluid consumed is measured in litres and duration of exercise is measured in hours.
For example, an athlete weighing 70kg before exercise and 68kg after exercise, taking on 1 litre of fluid in a two-hour session would have a sweat rate of 1.5 litres per hour.
Once you have measured your sweat rate, this will form the base to build your personalised hydration strategy from. You should undertake this test a number of times, in a range of conditions in order to identify any personal variation in sweat rate. Knowing how heat, duration, intensity, clothing and altitude affect your sweat rate will then allow for more specific planning around training sessions and races.
Monitoring urine colour with a colour chart, provides a means of assessing your personal hydration level(3,4). This should match colours 1-3, indicating that you are in a hydrated state. A darker reading would indicate a greater degree of dehydration and daily fluid intake should be personalised to avoid seeing readings darker than 4.
Acute changes in urine colour can be affected by large volumes of water in a short period of time and dietary supplements such as B-vitamins, vitamin C and beetroot juice. Therefore, this method of assessing hydration status should be undertaken at the same time of day under the same conditions.
The goal of a pre-exercise hydration strategy would be to start exercise in a euhydrated state. This can be achieved through 5-10ml of fluid per kilo of body weight in the 2-4 hours before exercise(1). This often equates to 500-750ml of fluid. You should achieve urine that is pale yellow in colour, while allowing enough time for excess fluid to be voided(2, 3). Fruit juice, GO Hydro and GO Electrolyte can be utilised here to help hit these requirements.
A 70kg athlete could follow the below plan the morning of a race, to consume 700ml of fluid as their hydration strategy
- 200ml of fruit juice / water with breakfast
- 3-4 hours pre-race – 300ml of GO Electrolyte
- Final hour before the race – 200ml GO Hydro
During Exercise Performance
Your personal sweat rate should be used to inform your fluid intake during performance, with the goal of preventing greater than 2-3% body weight loss(2, 3).
During exercise, general fluid recommendations are:
- Fluid intake should prevent more than 3% body weight loss via sweat
- This normally equates to 500-750ml per hour for an individual
- Include 240-300mg of sodium to aid fluid absorption and retention
- GO Hydro can be used for exercise lasting generally <90 minutes (depending on intensity)
- GO Electrolyte can be used for longer durations to hit both hydration and energy requirements
A post-exercise rehydration strategy should be designed to replace fluids and electorates lost during exercise and start the recovery process from exercise. The volume of fluid required to achieve this would be 150% of fluid lost during performance(5), in the 1-4 hours following exercise. An athlete losing 1.5kg body weight, via fluid losses, would need to consume 2.25L in the 1-4 hours post-exercise to optimally rehydrate.
- Use REGO Rapid Recovery to provide: fluid, carbohydrate, protein and electrolytes
- Consume additional fluids to replace 150% of fluid lost during exercise
- Thomas, D. T., Erdman, K. A., & Burke, L. M. (2016). American College of Sports Medicine Joint Position Statement. Nutrition and Athletic Performance. Medicine and Science in Sports and Exercise, 48(3), 543.
- Sawka, M. N., Cheuvront, S. N., & Kenefick, R. W. (2015). Hypohydration and human performance: impact of environment and physiological mechanisms. Sports Medicine, 45(1), 51-60.
- Casa, D. J., DeMartini, J. K., Bergeron, M. F., Csillan, D., Eichner, E. R., Lopez, R. M., & Yeargin, S. W. (2015). National Athletic Trainers' Association position statement: exertional heat illnesses. Journal of Athletic Training, 50(9), 986-1000.
- Maughan, R. J., & Shirreffs, S. M. (2008). Development of individual hydration strategies for athletes. International journal of sport nutrition and exercise metabolism, 18(5), 457-472.
- Baker, L. B., & Jeukendrup, A. E. (2014). Optimal composition of fluid‐replacement beverages. Comprehensive Physiology, 4, 575-630.