Carbs, Protein & Performance

The Athlete’s Kitchen
Copyright: Nancy Clark MS RD CSSD April 2011

Carbs, Protein & Performance
(first of a two part series)

What percentage of my diet should come from carbohydrates? … Should I exercise on empty? … How much protein should I eat after I lift weights? … Is whey the best source of protein?

These are just a few of the questions addressed at the 27th annual meeting of SCAN, the Sports And Cardiovascular Nutritionist’s practice group of the American Dietetic Association (www.SCANdpg.org). Over 400 sports dietitians gathered to learn the latest news from prominent sports nutrition researchers. I hope this information will help you choose a winning sports diet.

Carbohydrate Update
Louise Burke, PhD, Director of Sports Nutrition at the Australian Institute of Sport, addressed the following questions:

What are the best percentages of carbohydrates, protein, and fat for a sports diet: 40-30-30 or 60-25-15?

Neither! A better approach is to define nutrient needs in terms of grams per kilogram (or pound) body weight. For example, the International Olympic Committee developed these guidelines:

Intensity of exercise                    g carb/kg body wt                     gm carb/lb body wt
Low intensity                                       3-5 g                                       1.5-2.5
Moderate (~1 hour/day):                      5-7 g                                       2.3-3.2
Endurance (1-3 hours/d):                     6-10 g                                     2.5-4.5
Extreme (>4-5 hours/d):                      8-12 g                                     3.5-5.5

How much should I eat during long runs?

During long runs that last 1 to 2.5 hours, you want to target 30 to 60 grams of carbohydrate (120 to 240 calories) per hour. That’s about 1 to 2 gels or 16 to 32 ounces of a sports drink per hour (after the first hour, if you ate a pre-run meal or snack).

During runs longer than 2.5 hours, consuming 60 to 90 grams of different sources of carbohydrates (such as sports drink, banana, gummy candy) per hour is appropriate, as tolerated. Consuming the higher end of the range (90 g, as compared to 60 g) is associated with greater stamina and endurance.

How long does it take to refuel from a long, hard training run?

If you eat a carb-rich sports diet, you can replenish depleted glycogen stores in 24 to 36 hours post-exercise (with no running during that time). While it's important to pay attention to your recovery diet, most runners do not need to eat immediately after exercise unless they are doing double workouts. (Soon after exercise, yes; immediately, no.)

What can I do if I cannot tolerate any food during a long run?

Try mouth swishing with a sports drink. This sends a message to the brain that energy is forthcoming and you’ll feel more energetic. Swishing can enhance performance by 2% to 3% if you are exercising on empty and have not eaten pre-exercise—as often happens with morning runners. (Swishing seems to be less beneficial after a pre-run meal; more research is needed to verify these findings.)

Nancy Clark, MS, RD, CSSD (Board Certified Specialist in Sports Dietetics) helps both casual and competitive athletes win with nutrition. Her private practice is at Healthworks, the premier fitness center in Chestnut Hill MA (617-383-6100). Nancy Clark’s Sports Nutrition Guidebook and her food guides for new runners and marathoners offer additional information. They are available at www.nancyclarkrd.com. See also sportsnutritionworkshop.com.
 

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Bennett Cohen (the Savvy Runner) and Gail Gould are the Founders and Presidents of the International Association of Women Runners (IAWR). To learn more about this global community of women who share a passion for running, visit www.iawr-connect.com.

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