One of the hottest areas in sportswear right now is compression clothing and performance underwear.

Short sleeve, long sleeve and sleeve-less compression shirts as well as undershorts are all designed to enhance muscular performance and efficiency when taking part in all types of sporting activity.

Compression garments like New Zealand manufacturer Canterbury’s '‘Ionx' shirts allow muscles to perform efficiently and powerfully, meaning you expel less energy through the movement of the muscle. The Ionx technology uses Ionisation to create a Negative Ion field around the body which is known to enahnce well being and when worn against the skin, will increase blood flow and transport vital oxygen to muscles during activity!

Professor Mike Caine, head of sports technology and innovation at Loughborough University, compared the performance of athletes wearing IonX garments with those in normal gear and saw a difference. 'There seems to be a small-2.7 per cent- but significant improvement to repeated power output during high intensity exercise,' he said. Although Caine wants to carry out more research, he believes the technology could enhance athletic performance.

Ionized shirts have been dubbed 'wearable steroids' by the marketing bods. They were the talk of the Rugby World Cup and the eventual champions South Africa were one of the rugby countries to use them. However, this was only after The International Rugby Board asked the World Anti-Doping Agency (WADA) for a ruling. They are happy for now and WADA spokesman Frederic Donze said, 'Since there is no scientific publication supporting claims that changes in the body ion charges or magnetic field distribution enhance performance, and since such technologies do not contain prohibited substances, these technologies should not be considered as a banned method to date.'

High flying Premiership football team Portsmouth are so keen on the technology that they have done a deal preventing other sides in the division from using Canterbury's IonX for 'the immediate future' — thought to be several seasons. Bruce Vandenberg, the club's chief executive, said: 'It was very important to us that we were the only football club that could wear IonX so we sought to create an exclusive window.'

AIthough it has taken football a long time to catch on, this science has been known for centuries. The Japanese long ago realised that standing next to a waterfall, where ionisation also occurs, makes people feel better and German scientists in the 1930s used ionisation chambers to train bomber pilots to stay awake longer and be more alert. That technology was then applied to athletes in the former East Germany and Soviet Union.

It took an American textile company, who made protective suits for the Chernobyl clean-up operation as well as Ian Thorpe's 'shark-skin' swimming outfit, to work out how to incorporate the technology into fabric. Canterbury now have a 25-year agreement with that same firm. Joe Middleton , chief executive of Canterbury UK, said, 'With this kit elite athletes can recover quicker between training sessions and probably train half a day earlier. That's the feedback we're getting from these guys.'

Even Harry Redknapp is said to be a convert. Those negative ions must be a powerful force if they can win over a traditionalist like the Portsmouth manager.