Drop plasticine shapes down long tubes filled with wallpaper paste to investigate links between shapes and speed of movement, then watch how swimmers (especially butterfly events) and cyclists keep their bodies in the best shape for speed. See how weightlifters, pole-vaulters and gymnasts protect their hands (and also increase friction) by using bandages and talc. Investigate the way heartbeat and breathing rate vary according to body position and exercise. You could extend this to finding out how drugs, like caffeine in coffee and cola drinks affect the heart beat too. Look at the chemistry of respiration, especially the anaerobic phase and production of lactic acid (this might be seen in action if the marathon athletes hit "the wall").