19 July 2012 Last updated at 07:44

Do sports energy drinks and expensive trainers 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."

Trainers

The researchers also found no proof to back up Puma's claims that their trainers are "designed to... minimise injury, optimise comfort and maximise speed".

Puma, backed by Olympic champion Usain Bolt, did not offer a response.

The University of Oxford team looked at 431 claims in 104 sports product adverts for the joint BBC Panorama and British Medical Journal investigation.