On the bike leg, there is a trade-off between comfort and aerodynamics. "In simple terms, the flatter your back, the more aerodynamic you are," says Lumley.
"You do lose power, because your lower body isn't in the optimum position, but you are more efficient through the air. Find a balance that suits you, and ensure you are comfortable - over longer distances you'll move around in the saddle more if you're not settled."
A good fit
The setup of your bike is more important than what it's made of. "Get a bike that fits you correctly - for triathlon, not for a time trial," says Sturdy. "And get an expert to adjust the saddle and handlebars so they are in the optimum position. The best wheels - I use Strada - and frame do make a difference at the top level but they cost a lot of money."
Aero bars don't make you pedal faster, but they do encourage you to adopt the most efficient riding position for cutting through the air with minimum resistance. "They work by allowing you to present a 'point' around which airflow spreads, much like water over the tip of a torpedo," says coach David Tilbury-Davis (physfarm.com).
"Tri bars or aero bars start from as little as £30 and getting into a more aerodynamic position that still allows you to pedal fast is far more important than whether you spend £50 or £500.
"Eighty per cent of the drag on a cyclist comes from body position. At the sharp end, those wanting to gain precious seconds may pursue more expensive all-in-one aero bars that clean up the cable routing."
You need good core strength to maintain perfect position on the bike."Use a Swiss ball as you would for swimming-related exercises," says Lumley. "Also, go on an indoor bike, get your chin as low as possible and cycle with both your hands off the bars. This really works the core."
You can also take advantage of a technique used in another form of motor racing. In NASCAR (the US stock-car racing that features in the Tom Cruise film Days of Thunder), two cars work together by slipstreaming each other down the straights and running side by side through corners as they swap places on an oval circuit. This makes them faster than one car on its own. You can apply this, to some extent, to triathlon.
"Most races below the ITU World Series ban drafting," says Sturdy. "But there are still psychological benefits to be had from working as a group so it's worth practising."
"Drafting is a very inflammatory topic with triathletes," agrees Tilbury-Davis (physfarm.com). "Sitting in behind another competitor can reduce the work required by the person following by up to 20 per cent.
"You need to ride relatively close - that is, as close as you feel comfortable while still being able to brake if the person in front does so. Adopting this in a race is usually accompaniedby expletives from the competitor in front, at best, and a disqualification from race organisers at worst, because it is illegal in pretty much all age-group races."
But that doesn't mean you can't use it as part of your training to help boost speed endurance.
"Taking it in turns to draft with friends is a good way to practise riding faster than you normally could because you and your friends can take turns on the front riding hard while those behind recover a bit before their turn. Cyclists refer to this type of training as a 'chain gang'," says Tilbury-Davis.
The overall effect of being more aerodynamic is a smoother passage through the air, which helps whether you want to go faster or just conserve energy for the run.