Carbs, Protein & Performance Part Two

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

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

Train low, compete high?

Should I train with poorly fueled muscles, as a means to teach my body to burn more fat, so it spares the limited glycogen stores?

Training with low glycogen stores (“train low”) drives up the metabolic adaptations to burn more fat. By burning fat instead of glycogen, you’ll spare the limited glycogen stores. Theoretically, this should enhance stamina and endurance because glycogen depletion is associated with fatigue.

To date, “training low” has been most effective in research with untrained individuals. Training with low glycogen during low intensity workouts might be one way to stimulate the muscle adaptations to burn more fat (and thus spare the limited glycogen stores). But athletes should do their high intensity workouts when they are fully glycogen-loaded. Runners who exercise with depleted glycogen are unable to exercise at high intensity and that may hinder performance.

Exercise physiologist and researcher John Hawley, PhD of Melbourne, Australia acknowledged that training low and competing high (i.e. with high muscle glycogen availability) is receiving a lot of attention among serious endurance and ultra-distance athletes. Hawley suggests “train low” should be defined as “train at 50% of resting muscle glycogen, 50% of the time”—and only for selected sessions.

Training with low carbohydrate availability can be achieved by exercising with 1) low blood glucose, or 2) low muscle glycogen stores. Both generate adaptations that promote the training response and might be advantageous to competitive endurance athletes. Hawley cautions serious runners who “train low” that this compromises training intensity and may lead to inferior performance during an event, particularly if the athlete needs to do a competitive sprint to the finish. That final sprint often determines who wins the race…

Protein Update
Stuart Phillips, PhD, professor of kinesiology, McMaster University in Ontario, Canada presented an update on protein, answering these questions—

Do runners need more protein than non-athletes?

While the recommended protein intake for the average American is 0.4 gram protein per pound body weight (0.8 gram protein per kg), most exercise scientists agree that athletes need a more to optimize muscular development: 0.5 to 0.8 grams protein per pound (1.2 to 1.7 grams of protein per kilogram) body weight per day. However, most active women and men generally consume about 0.55 to 0.65 g protein/lb (1.2 g and 1.4 g protein/kg) body weight per day, respectively. They can appropriately meet their higher need without supplements.

How much protein do I need after I lift weights?

Consuming 20 grams of protein-rich food (Greek yogurt, tuna sandwich, 16 oz. chocolate milk) after resistance exercise is plenty to optimize the rate of muscle synthesis. Runners should then continue to eat protein and carbs at meals and snacks throughout the day. The highest rate of protein synthesis is 3 to 5 hours post-exercise. This raises the question: Should runners who work out twice a day plan to avoid exercising during that time frame? Remember: The “good stuff” (building muscle) happens during rest and recovery and the “bad stuff” (muscle damage) happens during exercise. Hence, rest is an essential part of a strength training program.

Should I buy whey protein supplements?

Probably not unless you are a frail, elderly person with a limited food intake. Drinking milk (20% whey, 80% casein) and eating a balanced sports diet can be as effective as whey supplements. Hard, hard work is the basic trigger for stronger muscles!

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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