Hamburg, Aug 3 (DPA) Summer is the season of lawn games and activities like indiaca, petanque, skittles, badminton, Frisbee or boomerang throwing. They all have two things in common: they are participant sports and they are very entertaining. They are also excellent at keeping the body fit.

'Those sports are played outdoors, they all involve intensive movement and help your bodily coordination,' says Theodor Stemper, a sports doctor at the University of Wuppertal in western Germany.

Softball, badminton and table tennis are about hitting a ball with a bat or racquet in a precise direction. 'That helps to train your coordination faculties,' says Stemper.

If you play those games at a slow pace the strain on the heart and joints will be moderate. But if you play competitively, you will need to be in good condition. A prerequisite for outdoor games played with a bat or racquet is a level playing field that has as few hazards to trip over as possible.

Among the traditional ball games played outside is boccia. Variations on the game include petanque and skittles.

The common factor is that a ball is rolled along a compacted surface of sand or grass with the aim of hitting a target. 'When you're buying one of those games keep in mind the material the balls are made of,' recommends Ulrich Brodowski, product manager at the German-based online sports equipment trader Sport-Thieme.