An inexpensively priced plastic ball with a sand filling behaves very differently from a steel ball or one made of wood.

Ball games are great for training coordination and dexterity but they also help your concentration.

'Of all sports you cannot say these types of ball games are the most healthy. But if your back is in good shape they are well worth trying out,' says Michaela Hombrecher from Germany's Techniker health insurance company. After all, a little exercise is better than none at all.

Sports where an object is thrown such as the discus or boomerang are all about coordination. More ambitious players will find they also provide the chance to run a lot, improving stamina and strength.

A traditional discus is made of plastic. 'An ordinary discus has a diameter of about 21 or 22 centimetres and weighs about 140 grams,' says Brodowski. Lighter disks are better for training but react very quickly to wind while heavy disks require more strength.

A lot slower than a discus is a soft nylon disk with a lead rim for stability. 'But if you play it on a hard surface such as asphalt the rim will become scratched and worn very quickly,' warns