A prefix is a series of letters, or a word, that is added to the  beginning of a word and changes the meaning. For example, in the  word midnight, mid is the prefix.
The more vigorous an activity, however, the more calories youâll burn. Changes in body weight are related to both the duration and intensity of play. Playing singles tennis at average intensity expends 300-600 kcal/h, while high intensity tennis training expends 450-900 kcal/h. Diabetes. The incidence of diabetes worldwide of persons aged 20 or above in 1995 was 4% (approx. 135 million), a figure that will increase to approx. 5.4% (300 million people) by 2025.
And a 160-pound person will burn 580 net calories in the same session. A 190-pound person will burn 692 excess calories playing doubles tennis for two hours. A 230-pound person will increase his calorie burn to 836 calories in two hours of tennis. In two hours, a 270-pound doubles tennis player will burn off an extra 980 calories.