Sit-Up

Sit-ups, or abdominal crunches, are best done as part of a balanced exercise program to enhance your fitness for other activities, such as riding and squash, but can also be regarded as an exercise activity in their own right. Some experts believe that muscle weakness in the abdomen is one of the main reasons for back pain and injury. The abdominal muscles should act as a support for the lower back. However, if those muscles are weak, too much strain may be exerted on the muscles of the lower back. Doing sit ups strengthens these muscles. FACTFILE

Calories burnt per minute: 4.8

Benefits: abdominal strength and endurance

Works on: heart, lungs, arms, shoulders and leg

Lie with both feet placed on the floor, hands behind your head or by your sides. Your knees should be bent to avoid stress to your back. Tuck your chin down into your chest and at the same time slowly raise your upper body to meet your knees. Now slowly resume your lying position. Avoid arching your back as you lie down.

Women should aim to build up to sets of between 15 and 35 while men should be able to build up to 30-75.