As many of us try to get fitter in this Olympic summer *squats*, Panorama investigates the sports products that promise to boost your performance. Are those pricey trainers worth the money? Can sports drinks really help you work out for longer? Are protein shakes any more effective at honing the physique than ordinary food? With exclusive access to the findings from a unique study by the British Medical Journal and Oxford University, reporter Shelley Jofre tests the science behind the bold advertising claims made by some of sport's biggest brands.