It sounds like an activity designed for masochists, but a triathlon is not as hard as it first appears, given the right training. And according to the British Triathlon Federation it has never been more popular, attracting devotees faster than any other sport in Britain.

Triathlon is a three-part race that requires participants to swim, cycle and run over set distances. It started with an event called “les trois sports” in France during the 1920s where competitors had to complete a 3km run, 12km ride and finish by swimming across the River Marne.

Today races are held over a range of distances to suit both amateurs and professionals. There are four main types: sprint (0.75 km swim, 20km bike ride, 5km run) Olympic (1.5km swim, 40km ride, 10km run), half Ironman (1.9km swim, 90km ride, 21km run) and Ironman (3.8km swim, 180km ride, 42.2km — a marathon — run).

More than 400 events have been sanctioned this year by the British Triathlon Federation, including the London Triathlon in August, which is contested over the Olympic distance and which boasted 11,000 participants last year.

Steve Heywood, a triathlete who has finished numerous Ironmans, believes a moderately fit person who prepares sensibly can take on a triathlon and finish it. You can devise your own training regime, but the federation recommends you join a club — there are more than 300 in the UK (see taking it further).

A club can hold many advantages over the doit-yourself training regime. It offers diet coaching and teaches you various techniques, such as the proper method of swimming (see illustration). This will help you cope with the “washing machine” conditions of mass swimming in open water. A club should also be able to lend bikes and wetsuits to beginners unsure of whether they want to take up the sport seriously.

Triathletes are suckers for gadgets too. Many competitors spend thousands on ultra-light bikes, heart-rate monitors, GPS watches, wetsuits and running shoes. But nobody can buy the most important requirement: fitness.

TAKING IT FURTHER

www.britishtriathlon.org The British Triathlon Federation site should be the first port of call for any aspiring triathlete

www.tritalk.co.uk Immerse yourself in the triathlon community. Read training blogs and advice

www.ultramarathonman.com If triathlon sounds too easy, learn from the American Dean Karnazes. He recently completed 50 marathons in 50 days

Triathlon tips

1 Don’t overdo it in the swimming stage. Find your own space in the water and swim at an even, relaxed pace to conserve energy

2 For a fast start to the cycling stage push the bike by holding the saddle, then transfer both hands to the handlebars. Swing your leg over the saddle, then find the pedals

3 To dismount for the final marathon stage swing both legs over the side of the bike while still moving and hit the ground running