Exercise is difficult to be precise about-it perhaps should be related as Kilocalories used per day as a function of Calorie intake and body weight.

Each exercise - swimming, walking, running can be given a caloric equivalent per unit of time e.g Swimming 500 kilocalories per hour for a 70 kg.man swimming at 1-2 miles per hour whose daily intake is 2,500 kilocalories………….but rarely is exercise so quantified.

In general terms exercise should be regular - every day if possible.

Exercise should be time limited-a minimum of half an hour.

Almost any exercise will do-walking, shopping, dancing as well as swimming, tennis, cycling.

It is suggested that depending on age, sex and fitness the aim should be to raise the resting pulse to a certain level, break sweat thus producing an appropriate stress on cardiovascular and respiratory system. This may be appropriate but there is little decisive evidence.