Nutrition

May 26, 2010

Post-Workout Nutrition

Make no mistake, what you eat following exercise can have a major impact on your results. After an intense workout, your body is in a catabolic state. It has spent a good deal of its stored fuels (including glycogen and amino acids) and in most cases sustained damage to its muscle fibers. The good news is that this presents a window of opportunity for anabolism. By consuming the proper ratio of nutrients during this time, not only do you initiate the rebuilding of damaged tissue and energy reserves, but you do so in a supercompensated fashion that fosters improvements in both body composition and exercise performance.

One of the primary goals post-exercise is to replenish glycogen (stored carbohydrate). Because glucose is depleted during training, your muscles and liver are literally starved for carbohydrate. In response, several adaptations take place. For one, the transporters responsible for bringing glucose into muscle cells (called GLUT4) become much more active. For another, your body stimulates the activity of glycogen synthase—the principle enzyme involved in promoting glycogen storage. The combination of these factors facilitates the rapid uptake of glucose into muscles, allowing glycogen to be replenished at an accelerated rate.

Carbohydrates are best taken in liquid form and should come from simple, high-glycemic sources. This is one instance where it is beneficial to spike insulin levels. You see, insulin has both anabolic and anti-catabolic functions, helping to increase protein synthesis, decrease protein breakdown, and shuttle glycogen into cells. And this is one instance where elevated insulin won’t promote increases in body fat. Because your muscles are in a depleted state, nutrients will tend to be used for lean tissue purposes rather than fat storage.

A combination of glucose and fructose is ideal, here. In addition to eliciting an insulin response, glucose is the primary source of muscle glycogen. Fructose, on the other hand, preferentially replenishes liver glycogen (glucose is of limited utility to the liver, a phenomenon called the “glucose paradox”). Thus, the two types of sugar work synergistically to restock the body’s glycogen stores.

Grape, apple, and cranberry juices are generally good choices since they have a high ratio of glucose to fructose. A good starting point is to consume ½ gram of carbs per pound of “ideal” bodyweight. Thus, if your goal weight is 120 pounds, then you’d consume 60 grams of carbs. For those who are “carb sensitive,” cut this amount back to ¼ gram of carbs per pound of body weight. Over time, assess how your body responds and modify the amount based on individual response.

The other main nutritional objective post-workout is to supply sufficient protein for tissue repair. If protein intake is inadequate following training, recuperation is shortchanged and results are comprised.

Protein should preferably be in the form of a high-quality protein powder. The idea is to saturate your muscles in amino acids, providing them with the raw materials to facilitate recovery. When amino acids are consumed following training, protein synthesis is increased more than threefold over fasting conditions, optimizing the development of lean muscle tissue.

A fast-acting protein such as whey works best. Because it is rapidly assimilated, whey reaches your muscles quickly, thereby expediting repair. And since your muscles are primed for anabolism, virtually all of the protein will be utilized for rebuilding with little wastage. Recent evidence suggests that combining whey with some casein can have even greater effects on protein synthesis, but this needs further study. Aim for ¼ gram of protein per pound of body weight, mixing the powder directly into your post-workout drink.

Refrain from consuming fats following your workout. Dietary fat slows gastric emptying, delaying the time that glucose and amino acids can enter the bloodstream and be used by the body. And if nutrients don’t reach your muscles in a timely fashion, results will suffer.

Caffeinated beverages should also be avoided during the post-workout period. Caffeine interferes with post-exercise insulin action, thereby impairing your body’s ability to replenish glycogen stores and utilize protein for muscular repair. Hence, wait at least a couple of hours after your workout before indulging in that cup of coffee or tea.

Ideally, you should consume your post-workout meal as soon as possible after training. The quicker you feed your body, the more it sops up nutrients and utilizes them for repair. Since blood flow is increased from the exercise bout, the delivery of protein and carbs is enhanced, resulting in greater muscle protein synthesis. But even if you are unable to consume your post-workout meal immediately upon cessation of training, all is not lost. The window of opportunity lasts for at least a couple of hours following exercise so just make sure you take in the specified nutrients as soon as you can.

Stay Fit!

Brad