During your workout your muscles use carbohydrate stores (called glycogen) for energy. As glycogen levels deplete, so does your ability to perform at your peak. Drinking flavoured milk immediately after working out replenishes your muscles’ energy stores and sets you up to perform better in your next exercise session.
In fact, research shows that people who drink milk straight after training are able to exercise longer in their next session than those who drink sports drinks or plain water.* And the harder you can train, the quicker you achieve your goals.
*Thomas KP et al. Appl Physiol Nutr Metab 2009; 34(1):78-82