P90X, which stands for power 90 extreme, is a home exercise program that combines rigorous strength training with a proper nutrition and dietary supplement plan. The program is made up of segmented training routines designed to prevent your body from adapting to the heavy weights -- this is known as reaching a "plateau" -- by changing the exercises and incorporating new movements. This allows you to experience bigger and faster gains than you might otherwise achieve. P90X, more than most programs, requires a strict and regimented routine, so the timing of nutrient consumption is critical.
Workout shakes contain a mixture of proteins, carbohydrates, vitamins and minerals. The purpose of the shake is to assist with muscle anabolism, a constructive metabolic process that uses small precursor molecules -- amino-acid building blocks from your diet -- to assemble large fibers which create bigger and stronger muscles. The simple sugars within the shake also speed up muscle recovery and restore depleted carbohydrate stores. The company behind P90X, Beach Body, sells a shake that combines major nutrients with antioxidants and nonessential nutrients that help protect cells, but you can also buy a number of shake brands from the store.
Immediately following a workout, the muscles are especially receptive to taking up nutrients. Since there is a delay between the time you drink the shake and the time that it becomes available to the cells, consuming the shake right before the workout will make the nutrients available when your muscles need them. These nutrients will reduce the presence of cortisol, a stress hormone that breaks down muscles, and stimulate the release of insulin without causing fat storage. In fact, the shake, when taken within the workout window, should increase insulin sensitivity, which means that your body responds well to the presence of carbohydrates. The opposite, insulin resistance, is the cause of diabetes.
A study published in 2001 in the "American Journal of Physiology, Endocrinology and Metabolism" suggests that the consumption of a protein and carbohydrate supplement before a workout produces a greater anabolic response in the muscles than the same supplement consumed after a workout. The researchers, from the University of Texas, found that the delivery of amino acids to the leg increased significantly and remained elevate for two hours following the exercise session.
According to Michelle Murphy Zive, a registered dietician, you should drink a protein shake within 30 minutes of your workout. You can also consume other fast-acting carbohydrates, such as rice, pasta, whole-grain bread or quinoa 45 minutes to 60 minutes after the workout. However, in the early stages of the P90X training, you will likely focus more on protein consumption than on carbohydrate consumption.