In general, the recommendations for fueling during exercise are:
- If you are exercising for less than 45 minutes, no need for fuel during exercise. (As always, enjoy a pre-exercise snack.)
- For 1 to 2 hours of exercise, target about 30 grams of carbs/hour (120 calories).
- For 2 to 3 hours of exercise, target about 60 grams of carbs/hr (240 calories).
- For more than 2.5 hours of exercise, target about 90 grams of mixed carbs (i.e. 360 calories of sports drink, candy, dried fruit or pretzels).
Some serious athletes train first thing in the morning without eating before/during exercise. While doing this may teach the body to burn more fat (hence spare limited glycogen stores), it's grueling and the verdict is unclear if this will enhance competitive performance. Stay tuned!
What happens if fueling during exercise creates intestinal distress?
You might want to swish and spit. When research subjects just swished and then spat out a sports drink, they improved their performance as compared to swishing and spitting just plain water. How could that be? Receptors in the mouth are linked to the brain. When the mouth gets a swish of sports drink, the brain gets the signal energy is on the way; it's OK to work harder.
Protein Update
Protein requirements are hard to define because the amount of protein your body needs depends on how many calories you consume. That is, if you are restricting calories, you require more protein than when you eat adequate calories; the protein gets burned for fuel. Dieting athletes should target at least 1 gram of protein/lb. (2 grams protein/kg).
Note: If you are dieting to lose undesired body fat, you are unlikely to lose only body fat and build muscle simultaneously. Building muscle takes energy; dieting restricts energy.
The protein recommendations for non-dieters who consume adequate calories are:
Healthy adults: 0.4 grams of protein/lb (0.8 gm protein/kg)
Strength athletes: 0.5 to 0.8 grams of protein/lb (1.2 to 1.7 grams of protein/kg)
Endurance athletes: 0.5 to 0.6 grams of protein/lb (1.2 to 1.4 grams of protein/kg)
Because the typical athlete's diet contains more than enough protein, most athletes do not need protein supplements. A protein-rich food with each meal and snack can do the job.
During endurance exercise, should you choose a sports drink with protein?
Not unless you prefer the taste; it does not offer performance advantages over a standard sports drink. The better time to consume protein is after exercise. That is, carbs combined with protein (as in chocolate milk, fruit yogurt, or spaghetti and meatballs) enhances muscle repair.
Consuming some carb/protein combos before you workout, as a part of your pre-exercise meal (cereal and milk, fruit and yogurt) is another option to bolster the supply of protein that will be available both during and after exercise for recovery. (Note: Athletes generally don't burn much protein for fuel during exercise unless their glycogen (carb) stores are depleted.) The bottom line: Meals and snacks with carbs as the foundation and protein on the side offer the right balance for endurance performance.