Going With the Grain: Sports nutritionist Beth Mansfield explains the crucial link between carbs and injury prevention

PLUS: How to snack for optimal performance

Carbohydrates have suffered from poor publicity since the recent low carb diet craze that swept across North America. Perhaps not coincidentally, we are also seeing increased rates of injury among calorie-conscious runners. What many athletes may not realize is that following a carbohydrate-rich diet doesn't just improve your performance on any given training or racing day - it also helps minimize the risk of injury.

What's the connection between injury and carbohydrate intake?

Eating carbohydrate-rich foods before, during and after your workout helps fight off the fatigue that comes with low muscle glycogen (stored carbohydrate). Keeping both blood sugar and muscle glycogen stores topped up will minimize those injuries that happen due to the exhaustion and muscle soreness caused by a lack of energy.

There is ample evidence in the scientific community that links a well-stocked muscle with a decreased likelihood of injury. That is because muscles with low muscle glycogen stores are primed for fatigue - they lose their strength and thus their ability to protect the joints from injury. Ever wonder why so many injuries occur in the last 10 minutes of training and competition situations?

Who is most vulnerable to glycogen depletion-related injury?

Runners training at moderate intensities for over an hour - that's anyone getting ready for a marathon or half marathon race - are the most vulnerable. It's all too easy to gradually drain your glycogen stores if you're training without eating a diet high enough in carbohydrates.

Working on your running technique, adding in hill training or a new component of training in an already fatigued muscle exposes those muscles to an unexpected demand, which makes joint injury even more likely. As a runner, you may be focusing in on specific exercises to make yourself stronger and fitter, but your diet is a crucial factor. If you neglect your diet, no matter how fit you are, you still may get injured.

So, what can you do to minimize injury?

The stress of trying to sustain a higher level of work output without sufficient fuel is thought to contribute to muscle damage. Eat a carbohydrate rich diet to ensure that you muscles are stocked up with energy BEFORE training - for example, eat a small carbohydrate rich snack or a liquid carbohydrate meal one hour before a training session. This ensures that you will be able to do more running before you run out of fuel.

While carbohydrate rich foods are every athlete's best energy foods, this does not mean slurping away on soft drinks, stuffing in plates of pasta or wolfing down brownies with ice cream in the middle of the night. It means choosing just enough nutrient-rich carbohydrate rich foods to meet training needs. Follow the guidelines below for proper food and fluid consumption before, during, and after exercise.

Before the workout:

Exercise intensity will dictate how much you will be able to eat and when in relation to your workout. The higher the intensity, the more time you want to give yourself to digest before the workout, eating at least a few hours prior.

If you are someone who has to eat something right before you exercise, that's okay. Just make sure you choose something rich in complex carbohydrate, low in fibre, fat and protein, and preferably liquid if it is within the hour before exercising. Using Canada's Food Guide, emphasize carbohydrate-rich selections from within each food group.

• White bread, bagels, wheat crackers, scones
• Low fibre cereals e.g. cheerios, cream of wheat with milk or yogurt
• Vegetable and fruit juices, fruit cocktail, fruit drink
• Low fat milk, flavoured milk/soy milk and yogurt/yogurt drinks

During the workout:

If the activity is vigorous and for longer than 90 minutes, take in some carbohydrate with your fluids - for example, sport drink or diluted fruit juice. For prolonged endurance events or activities (2 hours or more), eat small carbohydrate rich snacks (approx 15-20 gms/60-80 kcal of carbohydrate) every 20 minutes or so. This ingestion of carbohydrate during exercise should delay fatigue and enhance exercise performance. However, do remember that everyone is different and that what works for you is not necessarily the best choice for one of your training buddies!

Some good choices to consume during prolonged activity:

• Dried fruits
• Fig newtons
• Oatmeal cookies
• Energy or sport gels

After the workout:

Muscle glycogen may be measurably reduced after 45 minutes of moderate intensity exercise. The more glycogen you burn off the greater and more receptive your muscles will be to re-fueling. That means that the tougher a workout is (a function of intensity and duration), the more important it is for you to refuel...ASAP!

To maximize muscle glycogen stores, carbohydrate-rich foods should be consumed immediately after exercising. Timing is critical to restore muscle glycogen. Research shows that athletes who want to store maximal amounts of muscle glycogen for optimal training and peak performance should shift their intake of carbohydrate-rich foods to immediately after workouts. In fact, the best way to rapidly replenish muscle glycogen is to eat or drink carbohydrate immediately after exercise. When carbohydrate is combined with protein, this muscle glycogen storage is enhanced post exercise. Skim milk, fruit yogurt or chocolate skim milk are ways to encourage post workout refueling with carbohydrate-protein combinations. Make your own power punch for recovery nutrition by combining fruit and/or fruit juices with milk or plant based beverages.

Some good choices to consume after a workout:

• Latte with skim or 1% milk
• Carton of chocolate milk
• Small granola bar + water
• Piece of fruit (banana, orange, grapes)
• cup dried fruit + water
• Handful of salted pretzels + water
• 1-2 cups of sport drink
• GORP - easy on the peanuts - add some cereal instead + water
• bagel with jam + cup of tea

Snacking helps to bridge the gap between each meal so that you have a steady supply of energy for your run training and your physically-active lifestyle.

SOME HEALTHY SNACKING SUGGESTIONS

GREAT CHOICES -whole fresh fruit; apple banana, grapes... -frozen fruit, canned fruits in its own juice -raw vegetables; carrot sticks, broccoli florets, pepper sticks -3/4 cup (175g) yogurt, try low-fat versions -low-fat cheese or tofu based cheese -natural nut butters -melba toasts or whole-grain, low-fat unsalted crackers, crisp-breads, flatbreads -whole grain breads, bagels, English muffins, tortillas, pitas -whole-grain cereal -popcorn without fat or salt -fruit juices (unsweetened) -vegetable juices or cocktails (low-sodium)

GOOD CHOICES -dried fruits; raisins, prunes, apricots -canned or frozen fruits sweetened -dry-roasted unsalted nuts and seeds -low-fat microwave popcorn -Pretzels (low salt) -commercial muffins (read labels, can be high in fat) -graham crackers,  ginger snaps, low-fat arrowroot biscuits, social teas, fig bars, homemade muffins -sherbet, low-fat frozen yogurt, fruit ice, frozen juice bar

CHOOSE RARELY -sugar coated fruits -salted nuts and seeds -potato chips, corn chips, nacho chips, tortilla chips chocolate, chocolate bars, candies containing chocolate, butter, toffee or cream -soda pop; regular colas, orange drinks... -full fat ice cream -cakes, pies, pastries, croissant, doughnuts -cream sandwich cookies, commercial cookies