Sports nutrition tidbits

Consuming carbs during endurance exercise can delay fatigue by 30 to 60 minutes.
If you're eager to learn more about how to fuel your body for top performance, you might enjoy muscling through three pounds and 557 pages of Sports Nutrition: A Practice Manual for Professionals. The new fourth edition of this in-depth resource was recently released by SCAN, the sports nutrition practice group of the American Dietetic Association. (It's available at www.eatright.org; click on Shop Online.)

Although this resource book is written for primarily sports dietitians, strength coaches, athletic trainers and other health professionals who influence an athlete's eating practices, serious athletes might also like to feast on this hard-core (but well written and relatively easy to read) book that will answer all sports nutrition questions from A to Z, including alcohol, carbs, calories, fats, fluids, protein, vegetarian diet, weight gain, zinc and more.

To give you a taste of the information in the book, here are a few sports nutrition nuggets that might be of interest.

  • The average 150-pound athlete has only 1,000 to 2,000 calories of stored carbohydrates (glycogen), but over 80,000 to 120,000 calories of stored fat. Most of the fat is deposited in adipose tissue under the skin, but a little is also stored directly in the muscles and is an important source of fuel, especially during prolonged exercise.
  • Don't try to eat a fat-free diet! The recommended intake for athletes is about 0.5 grams fat/lb body weight/day. This equates to 60 to 80 grams per day of dietary fat for athletes who weigh 120 to 160 pounds. That's 15 to 20 teaspoons of butter! Preferably, the fat comes from healthful sources like nuts, peanut butter, olive and canola oils and avocado.
  • While some fat is good, excess calories of fat are fattening. Your body easily stores excess dietary fat as body fat. That's why you want to carefully carbo-load on pasta and breads, not fat-load on Alfredo sauce, butter, cheese or chips.
  • Your body stores carbohydrates in the muscles in the form of glycogen (1,200 to 1,600 calories) and also in the liver (300 to 400 calories); this feeds into the bloodstream (100 calories) and fuels your brain. During hard training that depletes your muscle glycogen, you enhance your body's ability to store even more glycogen; this enhances your ability to exercise for longer before "hitting the wall."
  • Athletes should eat at least 2 grams carb/lb. body weight per day. That's a minimum of 240 grams carb (about 1,000 calories) per day for a 120-pound woman and equates to 10 pieces of fruit or 5 cups of cooked pasta. Athletes in hard training actually should eat 4 to 5 grams carb/lb. No Atkins diet here!
  • Adult athletes require about 0.5 to 0.75 grams protein per pound (1.2 to 1.7 g pro/kg). Scientific evidence suggests if you eat more than 0.8g protein/lb (1.8g protein/kg), you'll burn the excess protein for energy. In other words, eating a very high-protein diet doesn't result in greater muscle gain, even with intense resistance training. To bulk up, eat more overall calories so you'll have abundant energy to build muscles.
  • Because eating before exercise can enhance performance, you should target:
  • 0.5g carb/lb body weight 1 hour pre-exercise
    1.0g carb/lb 2 hours pre-exercise
    1.5g carb/lb 3 hours pre-exercise
    2.0g carb/lb 4 hours pre-exercise






    This means, if you weigh 150 pounds, you need about 75 grams carbohydrates -- about 300 calories -- of carbs one hour pre-exercise, and 1,200 calories four hours out. This tends to be far more than most athletes consume. Experiment to learn how much your body can tolerate, and try to build up to this target if you currently eat less than this.

  • Consuming carbs during endurance exercise can delay fatigue by 30 to 60 minutes. Target about 1 gram carb per minute of exercise -- equivalent to 240 calories of carbs per hour if you weigh about 150 pounds. That's about 1 quart of Powerade per hour.
  • Consuming carbs as soon as tolerable after hard exercise enhances muscle glycogen replacement because: 1. Blood flow to the muscles is faster immediately after exercise, so carbs can get carried to the muscles faster;

    2. Muscles are better able to take up the carbs because of increased sensitivity to insulin, the hormone that helps transport carbs into muscles. Plan to have banana, fruit yogurt, fruit smoothie, and/or fig bars readily available.
  • Both liquid and solid carbs refuel the muscles equally well, so take your choice: chocolate milk or a pasta dinner.
  • While many athletes believe "thinner is better," don't try to get your body fat below five percent (men) or 12 percent (women). Each athlete has a fat percentage and body weight at which he or she performs best. Hence, you should listen to your body, and take note of how you feel and perform, as opposed to force your body to achieve a self-selected number.
  • Warning: Body-fat measurements -- even under research conditions -- can be plus or minus three to four percent. If you're told your body fat is 16 percent, it might be 13 percent or 19 percent. Just having a different person measure your body fat can significantly alter the measurement. Use body-fat measurements only as a guide and give yourself a body-fat range.
  • At rest, your body burns approximately 0.45 calories per pound per hour. If you weigh 150 pounds, you burn about:
    - 70 calories per hour of bed rest, or about 1,700 calories per 24 hours of doing nothing except staying alive.

    - about 375 calories per hour of moderate exercise, such as brisk walking at a pace of 15 minutes per mile.

    - about 1,200 calories per hour of high-intensity exercise, such as running at a pace of 5.5 minutes per mile.
  • Clearly, the harder you exercise, the more you can eat!

    But take heed: hard workouts followed by naps reduce your daily calorie needs. Athletes who turn into post-exercise couch potatoes commonly reward themselves with too much food and don't meet their desired weight goals.


    Sports nutritionist Nancy Clark, M.S., R.D., counsels both casual and competitive athletes in her private practice at Healthworks (617-383-6100), the premier fitness center in Chestnut Hill, MA. Her best-selling Sports Nutrition Guidebook ($23), Food Guide for Marathoners ($20) and The Cyclist's Food Guide ($20) are available at www.nancyclarkrd.com or www.sportsnutritionworkshop.com or by sending a check to PO Box 650124, W. Newton MA 02465.

    Copyright 2006 Nancy Clark


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