Olly Freeman is the rising star of British triathlon, with two top five World Cup finishes at the start of this season before a foot injury put him out of action. Like all serious triathletes, the 21-year-old treats his training as a virtual full-time job.

'I swim 25km, run 70 miles and ride on and off-road every training week, and I also hit the gym four times too,' he says. Although the challenge of swimming for 1.5km, cycling 40km and running for 10km obviously requires endurance, the best competitors recognise the need for occasional explosive power during races.

'Most people look at a triathlon course and just think about the two- to three-hour duration, but sometimes the first five swimming strokes can be the most important effort of the whole race,' says Freeman. 'If you miss getting into the pack on the swim, you miss the bunch on the bike, and by the run you're three minutes behind and out of contention.'

But working your tri muscles in the gym doesn't just give you an extra bit of oomph. 'There are loads of injury risks because you're doing three different sports,' says Freeman. Specifically designed stability exercises will strengthen joints and protect against injury.

Do the following workout two to three times a week to supplement your triathlon training and improve your performance.

Workout for triathlon strength:

• Clean to squat
• Medicine ball press-up
• Barbell calf raise.

Workout for triathlon stability:

• Swiss ball jackknife
• Side plank star
• Wobble cushion single-legged squat
• Stork hold.