Dehydration reduces blood volume, decreasing blood flow to skin and muscles. This leads to:
• Higher body temperature
• Reduced sweat rate
• Increased muscle glycogen use
• Increased perception of effort
•Higher heart rate
These effects impair concentration, skill, and performance. Starting exercise hydrated is essential to avoid these issues.
PRE-EXERCISE HYDRATION
Athletes should begin exercise hydrated to minimise fluid loss impacts. Use the ‘WUT’ method to assess dehydration:
Weight: Body mass loss >1% may indicate dehydration.
Urine Colour: Dark urine suggests dehydration.
Thirst: Thirst, combined with weight and urine checks, helps assess hydration.
If signs of dehydration are present, drink ~500 ml of water with 200-300 mg of sodium (or a GO Hydro tab) to start rehydration.
DURING-EXERCISE HYDRATION
Fluid losses vary, so intake should be personalised. To estimate how much you sweat, weigh yourself before and after exercise. For every gramme of weight you lose, you can assume you lost about 1 millilitre of sweat. Please use these equations:
Whole-Body Sweat Loss (WBSL) is calculated using this formula: WBSL (L) = [Body Weight Before Exercise – (Body Weight After Exercise – Fluid Consumed During Exercise + Urine Produced During Exercise)]
Whole-Body Sweating Rate (WBSR): WBSR (L/h) = WBSL / Exercise Duration
Try to drink enough fluids to prevent losing too much weight, as a 2-3% loss can negatively affect your efficiency. For example, a 60 kg runner who loses 2.4 litres (4%) of fluid should drink at least 1.2 litres while exercising. Adding electrolytes, like sodium and magnesium, through sports drinks such as Hydro helps recover what you lose and keeps your performance up.
POST-EXERCISE HYDRATION
It’s important to rehydrate after exercise, especially for players who train or compete multiple times. Two main things affect rehydration: the amount of fluid and the kind of fluid.
Midlife and older athletes should hydrate more because aging reduces thirst sensitivity, kidney efficiency, and sweat response, increasing the risk of dehydration and overheating
Drink 150% of the fluids you lose to make up for what you pee out. For example, if you lose 1 kg of weight (about the same as 1 litre of fluid), you will need about 1.5 litres of fluid to recover.
Fluid Type: Drinking water lowers sodium levels, which makes you less thirsty and causes you to urinate more. Drinks with salt, such as Hydro or GO Electrolyte, help the body keep fluids and stay hydrated.
