Friday, March 11, 2011

Refueling the Machine: Nutrition for Exercise

By Sarah Waybright, MS, Dietetic Intern, Penn State Extension, Adams County

Ever get that lethargic, drained feeling after exercising? Plagued by stiffness and exhaustion the day after being very active? Your reaction may be to blame your aerobic teacher, whine about the weights, or shake your fist in the general direction of the gym, but it could be what you aren’t doing that contributes to the way you feel as much as what you did in exercise. Eating (and drinking) strategically can help you recover, refuel, and push to the next level of fitness.

Many people think that by abstaining from eating before or after physical activity, they are boosting metabolism or burning more calories, but this overlooks an important concept: refueling your body is important to promote healing and rejuvenation of muscles. Your body will actually burn calories less efficiently with extended periods of undernourishment, which is why eating smaller meals more frequently can help with weight loss and to increase energy.

The trick is to strike a balance between energy expended and what you take in. During exercise, the first energy used is the quick-release glucose stored in your liver and muscle cells. Eating some carbohydrate within 30 minutes of finishing physical activity replenishes this store, and having a snack that contains carbohydrate before working out will help to maintain energy. Aim for about 20g of carbohydrate for a 130 lb. woman and 25g of carbohydrate for a 155 lb. man for each half hour of exercise1. See the table for suggestions for your recovery snack. The other important component of recovery nutrition is protein. As your muscles stretch and contract during exercise, tiny tears can form between the fibers. To build muscles back up, which makes you stronger and leads to even more effective exercise potential, a snack should contain both carbohydrate and high quality protein, like nuts, beans, lean meat, milk or yogurt. Don’t let the 30-minute window close before you’ve refueled! (Click table to enlarge.)

For the average person doing moderate exercise, and especially those trying to lose weight, it will not be necessary to eat additional calories in the form of carbohydrate and protein as a recovery snack. Just factor them into your daily needs and restructure the meals and snacks you eat around your workouts to optimize nutrition, healing, and performance. Eating a small meal about 2-2 ½ hours after exercise should be part of your schedule, as well as the initial recovery snack. Remember: a small amount of carbohydrate before physical activity, carbohydrates and protein within 30 minutes after, and a small meal a few hours after that.

Last but not least – remember to replenish fluids! In general, water is the best choice, but if you do strenuous work for more than an hour, supplements such as sports drinks may be a good choice to replace electrolytes. Weigh yourself before and after exercising to determine how much water your body needs: for each pound lost, have 2-3 cups of water2. For more food suggestions, tips and ideas, visit the websites listed below.

1. Richard B Kreider et al. ISSN exercise & sport nutrition review: research & recommendations. Journal of the International Society of Sports Nutrition 2010, 7:7doi:10.1186/1550-2783-7-7

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