Too many of today’s runners believe carbohydrates are “bad.” If that’s true, what does the latest sports nutrition research say? The following studies, presented at the American College of Sports Medicine’s 66th Annual Meeting indicate sports scientists agree that carbohydrates (grains, fruits, veggies; sugars, starches) can be health- and performance-enhancing sport foods. As you may (or may not) know, ACSM is a professional organization for sport science researchers, exercise physiologists, dietitians, doctors, and health-care providers for athletes (www.ACSM.org). Here are some answers to questions posed by ACSM researchers.
- Is fruit juice a healthful choice for athletes?
Yes, fruit juice can be an excellent source of carbohydrate to fuel muscles. Colorful juices (such as grape, cherry, blueberry, orange) also offer anti-inflammatory phytochemicals called polyphenols. In a study, subjects did muscle-damaging exercise and then consumed a post-exercise and a pre-bedtime protein recovery drink that included either pomegranate juice, tart cherry juice, or just sugar. The protein-polyphenol beverages boosted muscle recovery better than the sugar beverage.
- Does carbohydrate intake trigger intestinal distress for ultra-marathoners?
Not always. During a 37 mile (60-kilometer) ultra-marathon, 33 runners reported their food and fluid intake. They consumed between 150 to 360 calories (37-90 g carb) per hour, with an average of 240 calories (60 g) per hour. This meets the recommendation for carbohydrate intake during extended exercise (240-360 calories; 60-90 g carb/hour). The majority (73%) of runners reported some type of gut issues. Of those, 20% of the complaints were ranked serious.
Interestingly, the GI complaints were not linked to carbohydrate intake or to gut damage. In fact, a higher carbohydrate intake potentially reduced the risk of gut injury. (More research is needed to confirm this.) Unfortunately, runners cannot avoid all factors (such as jostling, dehydration, and nerves) that can trigger intestinal problems.
- We know that consuming carb during extended exercise enhances performance, but does it matter if marathoners consume a slow-digesting or a fast-digesting carbohydrate prior to a long run?
Likely not, but this can depend on how long you are exercising, and how often you want to consume carbohydrate. Well-trained runners consumed 200 calories of carbohydrate in UCAN (slow-digesting) vs. Cytocarb (fast-digesting) prior to a 3-hour moderately-hard run during which they consumed just water. At the end of the run, they did an intense sprint to fatigue. The sprint times were similar, regardless of the type of pre-run fuel.
That said, the slow digesting carb provided a more stable and consistent fuel source that maintained blood glucose concentration during the long run. Hence, endurance athletes want to experiment with a variety of beverages to determine which ones settle best and help them feel good during long runs. A slow-digesting carb can help maintain stable blood glucose levels without consuming fuel during the run. Fast-digesting carbs need carbohydrate supplementation throughout the exercise to maintain normal blood glucose.
Concluding comments: These studies indicate carbohydrate can help runners perform well. To be sure your muscles are fully fueled, include some starchy food (wholesome cereal, grain, bread, etc.) as the foundation of each meal. Consuming carbs from just fruit or veggies will likely leave you with inadequate muscle glycogen. Think twice before having just a chicken Caesar salad for a recovery meal.