Everyday Hydration for Training
With warmer months approaching, ensuring adequate hydration is essential for athletic training.
Studies show athletic performance decreases if:
- >2% of body weight is lost due to dehydration in hot weather.
- 3-5% of body weight is lost due to dehydration in cool weather.
In cases of severe dehydration, where 6-10% of body weight is lost, more prominent effects on exercise tolerance, decreases in cardiac output, sweat production, and skin and muscle blood flow can occur.
How to know you are hydrated?
To estimate daily hydration status, tracking early morning body weights can provide good insight on shifts in body water from day-to-day. However, this strategy only applies during weight maintenance. During weight loss or gain cycles, exact water losses may be difficult to track. In this case, observing urine color, frequency, and quantity is a useful way to determine hydration status. With adequate hydration, urine should be pale yellow in color.
While adequate fluids are essential during exercise, athletes should avoid reaching the point of over-hydration. If an athlete is urinating every 30 minutes or has a “sloshing” stomach, these might be signs of consuming too much fluid. Ideally, urinating every 2-3 hours is a good indicator of adequate hydration.
Athletes should aim to consume 5-10 mL/kg body weight (or ~2-4 mL/lb.) in the 2-4 hours prior to exercising.
For example, a 120 lb. athlete would need around 240-480 mL (or 1-2 cups), while a 180 lb. athlete would need around 360-720 mL (or 1.5-3 cups) of fluids.
During exercise hydration
Athletes should aim to drink enough fluids during exercise to limit total body fluid losses to <2% body weight. Regular body weights taken prior to and after exercise can help athletes estimate their sweat losses during training.
For example, a 1 kg (2.2lbs) body weight loss equals approximately 1 liter (or 4 cups) of fluids.
For most athletes, drinking 0.4-0.8 liters (~2-3 cups) per hour of exercise is adequate, depending on tolerance and experience.
Post exercise hydration
As expected, most athletes will end their exercise with a fluid deficit. Again, taking a post-exercise body weight can help estimate the amount of fluid lost during the training session. In the presence of excess sweat loss or prolonged exercise >2 hours, re-hydrating with an electrolyte containing drink may be necessary. If an athlete experiences weight GAIN after exercise, this might indicate over-hydration.
To replace fluid losses and maintain hydration, the most effective hydration strategy involves consuming around 1.2-1.5 times greater than the final fluid deficit.
For example, 1 kg body weight loss requires approximately 1.25-1.5 liters (or 5-6 cups) fluid replacement post exercise.
Tips for everyday hydration