Last month's nutrition article addressed nutrition before the workout. This piece will focus on nutrition for activity lasting more than one hour - when glycogen, fluid and electrolytes need repletion. Fine tuning nutrition during your training runs will allow you to reach peak performance on race day and continue to improve on your natural abilities.
Runner's Nutrition Toolkit:
Fluid:
Sweat evaporation is the primary avenue for heat loss in the body. Blood carries heat away from the exercising muscle to the skin where sweat evaporates on the skins surface. Dehydration increases muscle strain and the athlete's perceived effort to perform the same task. For any water deficit, there are alterations in physiologic function and consequences on performance. Therefore, drinking should be routine during any-high intensity exercise.
What we loose: fluid, salt, chloride, potassium and magnesium
Goals: Prevent <2% reduction in body weight
What to do out on the roads:
-4-8 ounces every 10-20 minutes (more fluid, more often for larger size and higher temperature)
- 13-26 oz per hour (if you are relying on a 28 oz fuel belt or squeeze bottle, you should be looking to refill at the local coffee shop one hour into your long run) This is the range your stomach can likely handle, without inducing sloshing of contents or possible nausea.
Hydration assessment: You can weigh yourself before and after exercise to get an idea of your individual fluid losses per hour which can range from 0.4 liters to 1 liter per hour (translates to about 0.9 pounds to 2.2 pounds on the scale) dependent on temperature, intensity of exercise and your size.
Sodium:
Sodium regulates fluid balance in the body and stimulates thirsts. Drinking a sports beverage or gu/gel/bar should do the trick. Sodium tablets should be reserved for those competing in ultra endurance events.
Carbohydrate loss and replacement during the run:
Proven to sustain high intensity exercise over one hour. If carbohydrate sources run low (from glycogen stores in the liver and muscle) the body will begin to rely on protein (AKA - you working muscles!) as a last resort for energy. The recommendation is 30-60 grams per hour.
- 500 – 1000mL of 6-8% carbohydrate sports drink
- minimum 1 packet gel
- ½ packet of Cliff Shot blocks (as a runner with a weak stomach, these are my personal favorite!)
- 1 bar
Benefit of Carbohydrate and Protein during exercise:
Recent studies have shown that ingestion of carbohydrate + protein (whey protein which is a complete protein vs. single amino acids found in other drinks) may further improve the athlete’s time to fatigue vs. a carbohydrate only beverage. Such a mixture will also reduce muscle damage. If your stomach can tolerate it, it may be worth a shot.
- ‘Accelerade’ is the only sports drink to fit this profile and has been used in the studies
- Energy bar with whey protein, washed down with appropriate fluid will do the trick if well tolerated
Benefits of Sports Drinks:
- Formulated to be easily digested during high intensity exercise.
- Salt (sodium, Na)
- Carbohydrate for immediate energy and less muscle damage
- fluid for hydration
- Prevents hyponatremia (water intoxication where blood becomes diluted)
Sports drinks are not created equally. The most effective sports drinks contain 6-8% carbohydrate for optimal stomach emptying and electrolytes including sodium, chloride, potassium and magnesium. Listed below are some of the better sports drinks recommended for during training.
- Gatorade
- Cytomax
- Powerade
Caffeine:
Caffeine consumption might help sustain exercise and will likely not alter hydration. Caffeine actually stimulates the release of free fatty acids, which are used during prolonged exercise and are the main source of energy when exercising at 65% or less of your VO2 max.
Why runners attempt a completely different regimen the day of the race continues to be a mystery to me. You should attempt using these guidelines for training runs over one hour in duration so you can apply what works on the day of the event.
Boston Running Center Nutritionists
