For bodybuilders, it is especially important to consume a diet with adequate amounts of protein to allow for the rebuilding and repair of muscle tissues. Milk is unique in that it contains two types of high-quality protein, which each possess different characteristics. The combined proteins in milk make it an ideal drink for bodybuilders, particularly when used after workouts.
Milk: Two Types of Protein
The protein in milk is 20 percent whey and 80 percent casein. Whey protein is a fast-acting form of protein used as a main ingredient in many muscle-building drinks and powders. Casein protein is a slower-digesting protein that is also used in muscle-building supplements. According to certified sports dietitian Debra Wein and registered dietitian Megan Miraglia, the combination of whey and casein protein present in cow’s milk can help restock the body's energy reserves, known as glycogen stores, while also triggering the growth of new muscles and the repair of damaged muscle tissue.
Milk Proteins Outperform Others
When compared to many other proteins, the proteins in milk are superior for muscle-building purposes. According to a 2009 paper published in the "Journal of the American College of Nutrition," when different types of protein, such as casein and whey, are combined, their effects on muscle protein synthesis can be amplified. When compared to other high-quality proteins, such as soy, they have a greater ability to support gains in muscle mass, particularly when combined with resistance exercises, such as those completed in a bodybuilding workout.
Milk After Workouts
Milk, and whole milk in particular, is an ideal drink for post-resistance exercise nutrition. A study published in 2006 in "Medicine and Science in Sports and Exercise" administered fat-free or whole milk to volunteers one hour after resistance exercise. The authors concluded that the amino acids in whole milk may be used more efficiently by the body, which can allow for a higher rate of protein synthesis.
For bodybuilders with a sweet tooth, there is more good news about milk. According to an article published on the U.S. Department of Agriculture website by Henry C. Lukaski, Ph.D., low-fat chocolate milk offers additional benefits because it's higher in carbohydrates than regular milk, with a greater than 3-1 carb-to-protein ratio -- which is the ideal ratio for refueling muscles after heavy exercise, according to Lukaski.