Having milk before exercising aerobically may be good for you, depending on your personal preferences, digestive capacities and planned intensity. A pre-workout milk snack is not inherently good or bad.
Milk supplies nutrition benefits that help with muscle, bone and cellular health. Many people can relate back to the "Got Milk?" slogans, connecting popular athletes and celebrities with drinking milk. For many people, milk doesn't sit well before or during activity, but if you're OK with it, it's fine to have milk as a part of your pre-workout regimen.
Benefits of Milk
Milk is a good source of protein, which is what the body demands for repairing and rebuilding the muscles you damage during exercise. Milk also supplies simple carbohydrates that are beneficial for your glycogen energy storage, as well as a substantial amount of calcium, which maintains significant bone integrity and density.
Combine the nutrition benefits of milk with resistance training, and your bones can have optimal integrity and density. While milk is most often recommended as a post-workout drink, a study in the 2013 issue of the Journal of Sports Sciences reports that, when consumed with a carbohydrate, a protein beverage may improve aerobic exercise performance.
Skim vs. Whole Milk
The position statement of the American College of Sports Medicine, published in the 2009 issue of Medicine and Science in Sports and Exercise, recommends that any pre-workout snacks be low in fat to facilitate digestion, so choose skim milk over whole milk.
Skim milk supplies approximately 1 percent of your recommended fat intake, and can be digested at a quicker rate. Skim milk contains about 65 calories fewer per cup compared to whole milk, which might be a boon if you're trying to lose weight, but could compromise muscle gain.
Negatives of Milk Before Exercise
The dairy and fat content of milk may cause problems during moderate to intense exercise because it's digested slowly. This can result in nausea, cramping and vomiting. Milk coats the mouth and throat with a thin film. Though it does not increase phlegm or mucus, the texture can cause a psychological effect that makes you cough or spit more.
Lactose intolerance is a common problem, too. Approximately 65 percent of people have a diminished ability to digest this sugar that's present in milk once they've passed infancy, notes the U.S. National Library of Medicine. Some people can tolerate small servings of milk or cultured dairy products, but combining a milk and a workout puts them over the edge of digestive comfort. Results of pre-workout milk could be cramping, nausea and loose stool.
Timing of Pre-Workout Milk
Correct timing supplies the key to balancing the ups and downs of having milk before exercise. If you do choose dairy products such as milk, consume it three to four hours before physical activity. This allows for the milk to be fully digested, limits the onset of nausea and allows your muscles to use the proteins optimally. A sample pre-workout snack could be oatmeal with skim milk or skim milk with a banana.