Do sports products really work?
The ads say they'll make you faster, but do sports products like energy drinks and fancy trainers really work?
An investigation into claims made by some popular sports products has found little evidence to back them up.
Lucozade is the UK's best-selling sports drink. But University of Oxford scientists couldn't find enough evidence to show it improves people's performance.
But the company that makes the drink, GlaxoSmithKline, disagrees.
It said: "All our claims are based on scientific evidence that have been reviewed and substantiated by the European Food Safety Authority."