Before exercise the body needs glycogen stores (storage form of glucose) in order to supply active muscles with enough energy (or ATP) during exercise. Consuming carbohydrate rich foods before exercise helps maximize glycogen stores in athletic individuals. What to eat depends on how much time there is before beginning exercise, body weight, and the type of exercise. With less time before exercise, smaller quantities of food that digest quickly are important (e.g. fruit smoothie, sports drink, fruit, cereal, or plain crackers). Liquids high in carbohydrates but low in fat, fiber and protein can be beneficial when time is tight since fat, fiber and protein slow stomach emptying, delay availability of energy from carbohydrates, and may upset the stomach.
- If there is less than 1 hour before exercise: try 1-2 servings (15-30g) carbohydrate + 8-12oz fluid
- 1/4 cup dried fruit + water
- 1 fruit + water
- 1 granola bar + 1 cup milk or water
- smoothie made with fruit, yogurt and water or milk
- 3/4 cup cereal or oats in milk + 1/2 banana
- If there are 1-2 hours before exercise: try 2-3 servings (30-45g) carbohydrate + small amount protein + 16-24oz fluid
- nut butter and banana sandwich + 1 cup milk + water
- egg sandwich + 1 fruit + water
- smoothie with fruit, yogurt, and milk or water + 4-6 crackers with protein + water
- If there are 2-4 hours before exercise: try a meal with 3-4 servings (45-60g) carbohydrates + 1 serving (8-20g) protein + vegetables + dairy + 16-24oz fluid
- 1 cup rice + 1/2 cup potatoes + 1 small chicken breast + 1/2 cup vegetables + 1 fruit + water
- tuna/egg/chicken/nut butter sandwich + 1/2 cup raw vegetables + 1 fruit + 1 cup milk + water
- 1 large hummus and vegetable wrap + 1/4 cup almonds + 1 fruit + water
For those who are strength training or involved in weight bearing interval training, the addition of a small amount of protein + 15-30g carbohydrates before exercise may improve muscle accretion and extend time to exhaustion. However clear guidelines regarding protein needs before strength training are not yet available.
Those who are physically active for general health likely do not require excess nutrition if balanced meals and snacks are being consumed. If you fatigue quickly when beginning to exercise, the addition of a small carbohydrate snack (like a banana) 15-65 minutes before exercising may be helpful.
For information about serving sizes, refer to http://www.hc-sc.gc.ca/fn-an/food-guide-aliment/basics-base/serving-portion-eng.php
References
http://www.ncbi.nlm.nih.gov/pubmed/23668654
http://www.dietitians.ca/Nutrition-Resources-A-Z/Factsheets/Sports-Nutrition/What-should-I-eat-and-drink-before,-during-and-aft.aspx
http://ceaccp.oxfordjournals.org/content/4/6/185.full.pdf+html
http://www.eatrightontario.ca/en/Articles/Frequently-Asked-Questions/Nutrition-and-Active-Living-FAQs.aspx#.VL2hOEfF8ps
http://www.motivenutrition.com/2013/01/20/grab-n-go-pre-workout-snacks/