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Copyright: Nancy Clark MS RD CSSD July 2009
Sports Nutrtion News from the American College of Sports Medicine
The American College of Sports Medicine (ACSM) is the world’s largest sports medicine and exercise science organization. At ACSM’s annual meeting in Seattle, May 27-30, 2009, over 5,000 exercise scientists, sports dietitians, physicians and health professionals gathered to share their research. Here are a few of the nutrition highlights. More highlights are available at www.acsm.org (click on “news releases”).
• Many athletes believe protein supplements are needed for building muscle. Yet, a study with college football players indicated no performance or muscle-building advantages from taking recovery protein in the form of a commercial supplement instead of standard food.
• Fruits and berries, including tart cherries, have anti-oxidant and anti-inflammatory properties. Runners who drank two 10.5 ounce bottles of tart cherry juice for one week before the 192 mile Mt. Hood to Oregon Coast relay race reported less post-race muscle pain than the placebo group.
• Black currants may also help reduce oxidative stress. Cyclists who consumed a pre-hard ride dose of black currant extract (the equivalent of about 1.2 cups of currants), experienced less oxidative stress.
• Research suggests food tends to be more health-protective than supplements. Taking high doses of C (2000 mg), E (800 IU), A (3000 IU), and selenium (200 micro-g) for six weeks offered no benefits to trained cyclists in terms of antioxidant effects and suppressing oxidative damage.
• Almonds (and all nuts, for that matter) are a positive addition to a sports diet. For four weeks, elite cyclists enjoyed about 60 almonds a day (~450 calories) prior to meals. They increased their anti-oxidant capacity 43% after a time trial as compared to the group who ate an equal number of calories from cookies. They also improved their time trial distance by 5% compared to the cookie group.
• Just rinsing your mouth with a sports drink may help you run faster! After an overnight fast (13-15 hours without food) and before and during a one hour time trial, 10 trained runners rinsed their mouth for five seconds with a sports drink or a placebo, and then spit it out. With the sports drink mouth rinse, they were able to run 365 meters longer in the time trial.
• An effective sports drink needs to be rapidly absorbed. Adding sodium (40-165 mg) to the beverage does not significantly slow absorption. (1973)
• Athletes who exercise in the heat might wonder if they can “hyper-hydrate.” Yes; more fluid is retained when a sports drink has a higher sodium content. Drinking a sports drink with double and triple the standard amount of sodium contributed to retaining 25% and 35% more water (12 and 17 ounces; 340 and 480 ml) than the standard sports drink.
• About 25% of athletic trainers use pickle juice to treat muscle cramps. Some report 1 to 2 ounces of pickle juice relieves cramps within 35 seconds. The mechanism is illusive because rapid relief must mean that pickle juice empties from the stomach very quickly. Yet, research indicates pickle juice empties very slowly from the stomach.
• “LactAway” is a sports supplement that claims to reduce blood lactate. A study with highly trained kayakers does not support that manufacture’s claim.
• Chocolate milk is a good recovery choice. Cyclists did an exhaustive bike ride, recovered with equal amounts of carbs in chocolate milk or a commercial recovery drink, and then the next day did a time trial. The commercial drink offered no additional benefits. Save your money!
• Glutamine is reported to enhance recovery by reducing post-exercise inflammatory responses. A study that compared a carbohydrate+essential amino acids beverage with or without glutamine taken during and after exercise offered no additional recovery benefits.
• Of 153 female soldiers starting basic training, 37% were iron deficient (serum ferritin <12 ng/mL). The women who took an iron supplement (100 mg ferrous sulfate) improved their two-mile run-times by 86 seconds as compared to the iron deficient women who were given no iron pills. Low ferritin is associated with feelings of depression and fatigue.
• During endurance exercise, consuming carbs in the form of an energy bar, a gel or a sports drink are all equally effective. That is, they all get used for energy at a similar rate.
• Many youth swimmers spend hours training for relatively short competitive events. A six-week study with 9 to 12 year olds suggests high intensity/low volume training offers the same benefits as lower intensity/high volume training (27 vs. 57 km/six weeks)—but in far less training time.
• How may calories are burned when lifting weights? Female subjects burned ~100 calories and the males ~ 210 in the half-hour session with two sets of 10 reps and 8 different exercises. But, if you subtract the calories for the resting metabolic rate that they would have burned just sitting quietly, they burned only ~70 (females) and ~160 (males) additional calories.
• Participants in the Western States 100 Mile Run burned about 15,850 calories in about 27 hours. This averaged about 600 calories/hour. That’s a lot of food!
• Severely obese people may need about 1800 calories just to be alive, and about 3,200 total calories a day. They don’t gain weight just smelling cookies…
• Exercise improves learning. Movement and physical activity in third graders has been linked with higher scores on tests involving problem solving. Among college students, those who spend more than three hours/day studying or have a grade point average of at last 3.5 are more likely to be physically active than students who study less and get lower grades.
• While American college students tend to exercise for weight control, fitness and physical attractiveness, Chinese college students tend to exercise for health and enjoyment—sustainable reasons to exercise!
• The Female Athlete Triad refers to the common problem of inadequate calorie intake, loss of menses, and stress fractures. The first line of treatment is to increase calorie intake or reduce expenditure by exercising a little less.
Strength training can help reduce the risk of stress fractures. Athletes with more muscle mass tend to have higher bone density. Dense bones are healthy bones!
• Fitness is more important than fatness. Unfortunately, only about 9% of Americans are “fit but fat” as compared to 30% who are “fit and not fat”.
What is your favorite work out food? Comment Below!
Nancy Clark, MS, RD, CSSD (Board Certified Specialist in Sports Dietetics) counsels both casual and competitive athletes in her private practice at Healthworks, the premier fitness center in Chestnut Hill MA (617-383-6100). Her Sports Nutrition Guidebook, and food guides for new runners, marathoners, or cyclists are available via www.nancyclarkrd.com. See also sportsnutritionworkshop.com.
(image: flikr, fotonics)
Hot off the press from three prominent nutrition and exercise associations—the American Dietetic Association, American College of Sports Medicine, and Dietitians of Canada—is the 2009 Joint Position Stand on Nutrition for Athletic Performance. While there is little earth-shattering news in this comprehensive document (available on http://www.eatright.org; on the left side of the screen, click on Position stands), the authors comprehensively reviewed the research to determine which sports nutrition practices effectively enhance performance. Here are a few key points, and the reminder that what and when you eat powerfully impacts how well you can perform. I hope this information entices you to “think again” if nutrition is your missing link.
• Don’t weigh yourself daily! What you weigh and how much body fat you have should not be the sole criterion for judging how well you are able to perform in sports. That is, don’t think that if you get to XX% body fat, you will run faster. For one, all techniques to measure body fat have inherent errors. (Even BodPod can underestimate percent fat by 2 to 3%.) Two, optimal body fat levels depend on genetics and what is optimal for your unique body. Pay more attention to how you feel and perform than to a number on the scale.
• Protein recommendations for both endurance and strength-trained athletes range from 0.5 to 0.8 grams per pound (1.2-1.7 g/kg) body weight. For a 150 lb. athlete, this comes to about 75 to 120 g protein per day, an amount most athletes easily consume through their standard diet without the use of protein supplements or amino acid supplements. Vegetarian athletes should target 10% more, because some plant proteins (not soy but legumes) are less well digested than animal proteins.
If you are just starting a weight-lifting program, you’ll want to target the higher protein amount. Once you have built-up your muscles, the lower end of the range is fine.
• Athletes in power sports need to pay attention to carbohydrates, and not just protein. That’s because strength training depletes muscle glycogen stores. You can deplete about 25% to 35% of total muscle glycogen stores during a single 30-second bout of resistance exercise.
• Athletes who eat enough calories to support their athletic performance are unlikely to need vitamin supplements. But athletes who severely limit their food intake to lose weight (such as wrestlers, lightweight rowers, gymnasts), eliminate a food group (such as dairy, if they are lactose intolerant), or train indoors and get very little sunlight (skaters, gymnasts, swimmers) may require supplements.
• If you are vegetarian, a blood donor, and or a woman with heavy menstrual periods, you should pay special attention to your iron intake. If you consume too little iron, you can easily become deficient and be unable to exercise energetically due to anemia. Because reversing iron deficiency can take 3 to 6 months, your best bet is to prevent anemia by regularly eating iron-rich foods (lean beef, chicken thighs, enriched breakfast cereals such as Wheaties and Total) and including in each meal a source of vitamin C (fruits, vegetables).
• Eating before hard exercise, as opposed to exercising in a fasted state, has been shown to improve performance. If you choose to not eat before a hard workout, at least consume a sports drink (or some source of energy) during exercise.
• When you exercise hard for more than one hour, target 30 to 60 grams (120 to 240 calories) of carbohydrate per hour to maintain normal blood glucose levels and enhance your stamina and enjoyment of exercise. Fueling during exercise is especially important if you have not eaten a pre-exercise snack. Popular choices include gummi candy, jelly beans, dried fruits, as well as gels and sports drinks. More research is needed to determine if choosing a sports drink with protein will enhance endurance performance.
• For optimal recovery, an athlete who weighs about 150 pounds should target 300 to 400 calories of carbs within a half-hour after finishing a hard workout. More precisely, target 0.5-0.7 g carb/lb (1.0-1.5 g carb/kg). You then want to repeat that dose every 2 hours for the next four to six hours. For example, if you have done a rigorous, exhaustive morning workout and need to do another session that afternoon, you could enjoy a large banana and a vanilla yogurt as soon as tolerable post-exercise; then, two hours later, a pasta-based meal; and then, another two hours later, another snack, such as pretzels and orange juice.
• Whether or not you urgently need to refuel depends on when you will next be exercising. While a triathlete who runs for 90 minutes in the morning needs to rapidly refuel for a 3-hour cycling workout in the afternoon, the fitness exerciser who works out every other day has little need to obsess about refueling.
•Including a little protein in the recovery meals and snacks enhances muscle repair and growth. Popular carb+protein combinations include chocolate milk, yogurt, cereal+milk, pita+hummus, beans+rice, pasta+meat sauce.
•Muscle cramps are associated with dehydration, electrolyte deficits, and fatigue. Cramps are most common in athletes who sweat profusely and are “salty sweaters.” They need more sodium than the standard recommendation of 2,400 mg/day. Losing about 2 pounds of sweat during a workout equates to losing about 1,000 mg sodium. (Note: 8 ounces of sport drink may offer only 110 mg sodium.) Salty sweaters (as observed by a salty crust on the skin of some athletes) lose even more sodium. If that’s your case, don’t hesitate to consume salt before, during and after extended exercise. For example, enjoy broth, pretzels, cheese & crackers, pickles and other sodium-rich foods. The majority of active people can easily replace sweat losses via a normal intake of food and fluids.
Final words of advice: If you can make time to train, you can also make time to eat well and get the most out of your training. Optimal sports performance starts with good nutrition!
Nancy Clark, MS, RD, CSSD (Board Certified Specialist in Sports Dietetics) counsels both casual and competitive athletes in her private practice at Healthworks, the premier fitness center in Chestnut Hill MA (617-383-6100). Her Sports Nutrition Guidebook, and food guides for new runners, marathoners, or cyclists are available via http://www.nancyclarkrd.com. See also sportsnutritionworkshop.com.
Copyright March 2009: Nancy Clark MS RD CSSD
2009 Sports Nutrition Guidelines