Notes from Daryl Reynolds lecture “Fluids and Foods for Exercise”

Fluids & Foods for Exercise

Intake PRIOR TO Exercise
• Consume 100-400 gm of carbohydrate 1-4 hours prior to your event. 1-4.5 gms/kg of body weight.
• Consume 400-600 ml of fluids 2-3 hours before exercise
o For events less than 1 hour water should be the beverage of choice.
o For events greater than 1 hour, a carbohydrate (sports, not meal replacement) beverage with <8% carbohydrate is the ideal choice.
• An additional 300-500 ml of fluid intake is recommend for endurance athletes 15-30 minutes prior to their event particularly if they are exercising in the heat.
• Fluids are absorbed more quickly when they are taken in moderate quantities of between 100-250ml and when cool/cold.

Food and fluid intake during exercise
• Exercise intensity above 75% of VO2max slows gastric emptying and may cause gastrointestinal upset. The higher your heart rate the lower the absorption of food/fluid when you are above 75% of your maximum heart rate.
Fluids
• Empty from the stomach quickest when they contain <2.5% carbohydrate and are cool/cold.
• Those who experience sloshing fluid in their stomachs during long periods of exercise may benefit from diluting normal sports drinks (6-8% carbohydrate concentration) to 2-4% or ½ of their normal concentration. This can allow the fluid to be absorbed more quickly. Note: it also reduces the amount of carbohydrate/salts provided, which can hasten glycogen and salt depletion.
• The average rate of gastrointestinal absorption of fluids is approximately 30 ml/min; however your sweat rate can be up to 50 ml/min.
• For events less than one hour 180-240 ml of water every 15 minutes is recommended.
• For endurance events or high intensity intermittent exercise of 1 – 4 hours in duration 150-300 ml of a sports beverage is recommended every 15-20 minutes.
Foods
• For endurance events research shows that consumption of 30-60 grams of carbohydrate/hour during exercise delays fatigue and improves performance.
• The maximum absorption rate of carbohydrate from the intestinal tract is roughly 1gm/min or 60 gm/hr.

How to figure out your numbers: Questions to self:

How long is your event? Water<1hour vs. Sports drink>1hour
How much do you weigh? Carb intake ~ 1gm/kg/hr before and ½ gm/kg/hr during

Source of Information: Advanced Exercise Nutrition, Human Kinetics ©2002