Water and sports drink don't hold a patch to milk when it comes to replacing the fluid and salts lost through sweat after exercising.
Milk is rich in sodium, potassium and other salts that are vital for health but lost in large quantities through sweat.
Physiologist Susan Shirreffs at Loughborough University's school of sport found that drinking a glass of milk is what people should be doing after a workout, for it keeps the body rehydrated four times longer than either water or sports drinks.
Dr Shirreffs, as a part of her study, analysed the effects of different drinks a group of young men and women in their early 20s after they had trained on exercise bikes in a hot room.
She found that not only did milk keep the subjects rehydrated for four hours as compared to the one hour with Water and Powerade, a sports drink by Coca-Cola, but that the combination of sugar, fat and protein in milk is removed from the body less slowl.
Dr Shirreffs said that the study showed that milk was a good alternative to water and costly sports drinks for people, especially athletes.
"It will give them a little bit of protein and a little bit of carbohydrate and is cheaper as well," the Daily Mail quoted her, as saying.
Dr Carole Lowis, of the Dairy Council for Northern Ireland, said: 'As a means of getting fluid back into your system, milk offers a wide range of essential vitamins and minerals. It is an excellent drink for anyone who is serious about their health and wellbeing.'
The study is published in the British Journal of Nutrition.