Information About Carbohydrates
Carbohydrates are the body’s primary source of metabolic energy fuel. They are the exclusive fuel source for red blood cells and the primary fuel for nerve cells. Consuming an adequate amount of carbohydrates before intense exercise will prevent the breakdown of muscle, sparing it from the metabolic process of fueling the body.
The different types of carbs play different roles in the context of sport and exercise nutrition. Monosaccharides (single-molecule unit) and disaccharides (double-molecule unit) are commonly referred to as sugars, while larger chains of monosaccharide molecules (polysaccharides) are known as complex carbohydrates or starch, fiber, and glycogen. The three monosaccharides are glucose, galactose and fructose which then pair up to make up the disaccharides, maltose, sucrose, and lactose.
Starch and Fiber are both sourced from plants. Glucose is stored as starch within plants and fiber is the remaining non-starch polysaccharides. Our bodies store carbohydrates (glucose) as glycogen in the liver and skeletal muscle.
Having muscles fully stocked with glycogen is important for exercise and sport performance as the body relies on it to fuel muscles. While a low-carb diet is also typically lower in calories resulting in weight loss, it is not a diet conducive to anything but low intensity exercise. The body’s liver and muscle glycogen stores are rapidly depleted once a low-carb diet is started. When muscle glycogen stores are depleted the athlete experiences fatigue and will be forced to stop or significantly reduce the intensity of exercise, allowing the body time to replenish muscle glycogen. This is particularly important in aerobic endurance athletes as their bodies are under constant stress, with no recovery periods, for extended periods of time. However, that is not to say carbs are not important during anaerobic exercise. During exercise sets consisting of many high-intensity repetitions with short recovery periods, such as sprints, the muscle glycogen stores must provide a constant supply of fuel. During strength training, the consumption of carbohydrates increases insulin secretion. Insulin acts as an anabolic hormone, promoting muscle growth and preventing muscle breakdown. The recommended daily consumption of carbs varies between these athletes with endurance athletes requiring more and anaerobic athletes fewer but a general rule of thumb for athletes in training is 5 to 7 g of carbs/kg body weight. For perspective, a nonactive adult requires about 5 g carbs/kg body weight.
Eating the proper foods at the proper times will mitigate glycogen depletion by ensuring the athlete begins the activity with their muscles fully stocked with fuel and maintains them throughout the exercising bout. Choose carbohydrates with low glycemic index (GI) scores for meals between work outs for prolonged recovery. Low GI foods provide a low-level of glucose exposure to muscles over an extended amount of time, giving muscle a chance to replenish their glycogen supplies without an unnecessary insulin spike.
Foods with higher GI ratings are also an important player in proper exercise nutrition. High GI carbs are vital in maintaining proper blood glucose levels during prolonged exercise and for the rapid recovery of muscle glycogen stores. These foods can be eaten just before, during, or after, activity for a quick boost.