Give your nutrition skills a workout

Dietary needs vary from sport to sport, but one fact remains constant: What you feed your body is as important as how you train it

By LESLIE BECK

Wednesday, June 1, 2005 Page A17

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If you're serious about exercise, you probably know that fuelling your body is as important as training it. It's well established that eating the right foods, at the right times, can enhance physical performance during training and competition.

And you don't have to be a world class athlete to reap the benefits of nutrition. Whether your fitness regime includes cycling to and from work, 30 minutes on a treadmill or building up to marathon mileage, you need to eat right if you want your body to perform its best.

Though dietary needs vary from sport to sport, a certain formula holds true for athletes at all levels. A fitness-friendly diet must contain carbohydrates for fuel, protein to build and repair muscles, vitamins and minerals to support muscle-building and energy metabolism, and fluids to cool the body.

Carbohydrates are the body's preferred energy source for daily physical activities and high-intensity exercise. Once digested, carbohydrate-rich foods are absorbed into the bloodstream as glucose.

Glucose that's not used immediately for energy is stored in muscles as glycogen -- the primary fuel for all types of exercise.

The more glycogen your muscles tuck away, the longer you'll be able to continue exercising before feeling tired. That's why carbohydrate loading, the practice of scarfing down large portions of pasta or other starchy foods, is common among endurance athletes.

Those extra carbs can power an athlete through a 26-mile marathon or the stages of a triathlon.

To keep muscle glycogen stores primed for exercise, 55 to 65 per cent of your daily calories should come from nutrient-packed carbohydrate-rich foods such as whole-grain breads and cereals, fruits, legumes, soy beverages, milk and yogurt.

Protein needs increase with exercise, but not dramatically. Protein is used to repair muscle tissues that break down during exercise, and to maintain the immune system.

Most active people don't need protein powders and protein bars to meet their needs. Studies show that most athletes can easily get their daily protein requirements from a mixed diet.

Nutrition before exercise

A pre-exercise meal is needed to prevent early fatigue caused by low blood-sugar levels, to ward off feelings of hunger, and to guarantee optimal hydration. The ideal preworkout meal contains mainly carbohydrates and fluids, plus a little protein. Research suggests that consuming six grams of protein before strength training can enhance postexercise muscle repair.

A pre-exercise meal should also be low in fat and fibre so that it empties from the stomach faster.

Good preworkout snacks include whole grain cereals, such as Cheerios and Shreddies, with low-fat milk, whole-grain toast with jam, a small turkey sandwich, yogurt and a piece of fruit, or an energy bar.

Liquid meals are good alternatives for athletes who require fuel immediately prior to exercise, who have a sensitive stomach, or when schedules do not allow time for meals. Homemade smoothies prepared with low-fat milk and fruit, or commercial products such as Ensure HP (High Protein), provide carbohydrates, protein and fluid in an easily digestible form.

Pre-exercise meals should be smaller the closer they are eaten to the time of exercise.

Eating too much food before a workout can cause stomach cramps. Allow three to four hours for a large meal to digest, two to three hours for a smaller meal, and one to two hours for a small snack.

Nutrition during exercise

Consuming carbohydrates during exercise that lasts longer than one hour helps maintain blood-sugar levels at a time when muscle glycogen stores are diminishing. Studies have found that carbohydrate feedings improve performance in endurance sports, such as running, cycling and triathlons, and reduce fatigue during stop-and-go sports, such as basketball, football and rugby.

In general, athletes should consume 30 to 60 grams of carbohydrates per hour of exercise. Good choices include sports drinks (e.g. Gatorade, PowerAde, All Sport), energy gel packets (e.g. PowerGel, Clif Shot), energy bars, bananas, fig bars, low-fat granola bars and dried fruit snacks. Most energy gels provide 25 grams of carbohydrates from pure sugar.

The snack you choose will depend on the type of exercise you're doing. Runners prefer carbohydrates in a portable and compact form that's easy to consume -- energy gels, energy bars and sports drinks are popular. Snacks like bananas, dried fruit, yogurt tubes (pack them frozen) and energy bars work well for cyclists.

Nutrition after exercise

A postexercise meal that's high in carbohydrates will help replenish muscle glycogen and will keep you from feeling tired after a hard workout. Research suggests that consuming a little protein along with carbohydrate can optimize glycogen replacement and muscle-tissue repair.

Timing is important, too. If you delay consuming carbohydrates for too long after exercise, muscle recovery can be impaired. Muscles are most receptive to food soon after exercise, when blood flow to them is high and glycogen-building enzymes are most active. Recovery foods should be eaten within 15 to 30 minutes after stopping exercise.

It's recommended that athletes consume 50 to 100 grams of carbohydrates, along with 10 to 20 grams of protein, every two hours after exercise, until the next meal is eaten.

Remember to drink up

Drinking adequate fluids is essential for top athletic performance. Dehydration, even in small doses, can cause early fatigue during exercise. Athletes should consume at least nine to 12 cups (2.2. to three litres) of fluid each day.

During exercise, it's important to drink 125 to 175 millilitres of water every 10 to 15 minutes. Sports drinks are recommended during exercise that lasts longer than one hour.

After exercise, replenish lost fluids by consuming 500 ml of fluid for every pound of body weight lost.

Leslie Beck, a Toronto-based dietitian at the Medcan Clinic, is on CTV's Canada AM every Wednesday. Visit her website at lesliebeck.com.