Carbohydrates and Physical Activity

Because physical activity dramatically increases the rate of energy expenditure, athletes must strategize in order to best supply the needed energy to achieve success. It is critical for athletes to obtain sufficient total energy intake to support total energy requirements, including those for normal tissue maintenance, growth (in children and adolescents), tissue repair, and the energy requirements of the activity itself. It is impossible to discuss the ideal distribution of energy substrates without first conceptualizing how to best meet total energy needs. Although this may seem a logical and simple act, virtually all surveys have found that athletes fail to consume sufficient energy to fully satisfy their needs. This is much like planning to take a Ferrari on a 100-mile trip, and you appropriately put high-octane gas in the fuel tank-but only enough of it to go 80 miles. The Ferrari just won't get there, and poorly fueled athletes will also have difficulties doing what's required to be optimally competitive. Once a strategy has been established for obtaining sufficient energy, then athletes can reasonably consider how to parse the energy into the optimal distribution of energy substrates: carbohydrate, protein, and fat. It is generally accepted that athletes should consume sufficient carbohydrate to meet the majority of their exercise-related energy needs, plus enough carbohydrate to restore muscle glycogen stores between exercise sessions.¹⁶

Ideally, athletes should consume complex carbohydrates when possible but should consume simple carbohydrates during and immediately after exercise. Other energy substrates (protein and fat) should also be consumed to fulfill total nutrient requirements, but carbohydrate should remain the predominant energy source. It is difficult for athletes to take in sufficient energy and carbohydrate unless there is a well- established plan to do so. Athletes would do well to remember that training alone, without a sound nutrition plan to support the training, will be self-limiting.