Just imagine a world without aerodynamics - there would be no flight, cars would be square and humans would fall over in a gust of wind. Formula One races would take days.
That got us thinking. Racing cars have evolved to optimise speed in every conceivable way, but just because they're machines doesn't mean we can't learn from them.
"Improved streamlining will make you more efficient in each discipline and you'll gain 'free speed'," says coach Steve Lumley (steve-lumley.net). "That is, you'll be going faster for no extra effort. And many small gains can be made from improving your technique and training."
Triathlon kit has evolved, too; the hi-tech fabrics and materials in your trisuit, and on your bike and running shoes, have been developed to maximise the performance of the one variable that kit makers can't control - you.
OK, you can't head off to a wind tunnel and manufacture a new, faster body, but you can
use aerodynamics to improve your form and kit selection, and get that new PB. Click through our slideshow to find out how.
Your body position is key during the swim if you want to be fast and efficient in the water.
"The main problem for triathletes - in fact, most nonspecialist swimmers - is that the hips and legs sink," says Lumley.
"People often overemphasise a long, smooth stroke, which looks impressive but means there is a dead point in the stroke where there's no forward propulsion. Improving your kick will help that."
Try leg and core exercises (crunches, jack-knifes, raises) that require you to lie prone on a Swiss ball, which mimics your swimming position.
Improving your stroke is easier when you can recognise flaws. "Tie a band around your ankles and swim without kicking," says Lumley. "This makes you more aware of what your legs and hips are doing."
Try to avoid lateral movement, and keep your entire body as streamlined as possible.If you're from a running background, you are likely to have stiff ankles.
"An effective stroke requires flexible ankles," says Lumley. "Train with fins, as these will help increase flexibility over time."
Don't get stuck in a crowd, especially if you are still perfecting your stroke. "Stay out wide but also think about how the course is laid out," says pro triathlete Tom Sturdy, who also has a master's in biomechanics.
"I once decided to stay left during the swim, only for the whole field around me to turn left into me at the buoy, so I learned to stay on the outside of the pack. You also need a position that makes sighting easy, so use the shore if you can't see ahead."
Taking care of your trisuit is vital, too. "I only wear mine for racing, unless it's new and I want to try it out," says Sturdy. "Don't wear it in a pool because the chlorine will affect it; hand wash only, even if the label says it's machine washable, and don't hang it out in direct sunlight."
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.
Like a Formula One driver, you should cover the minimum distance possible. "Take the racing line," says Lumley.
Think about how a racing car swings in to a bend from out wide to hit the apex before it drifts out again under acceleration. This is the fastest way for humans, too.
"Numerous studies have shown it's best to run at an even pace, or aim for a slight negative split, where the second half is faster than the first," says Lumley. "Metabolically, this is the most efficient way to run." It also means you have energy in reserve for a duel with a rival," he says.
"How to run properly is a contentious subject," says biomechanics expert Sturdy. "There is an efficient way to run, but there are infinite variations because of our different body shapes.
"You want to be travelling forward, not vertically, so I run in a pair of shorts with a heavy weight in the back pocket. That way I can feel if it's going up and down too much and correct it so I have a lower centre of gravity."
Refuelling has been banned in F1 - but not in triathlon. And you need to make your own pit stops as fast as possible.
"I use Clif Bar Shot Bloks, which are electrolyte jellies that dissolve in your mouth," says Sturdy. "I don't like too much water in my stomach, so will only take small sips, but I always have the jelly in my mouth - without chewing - even if I don't necessarily need it."
Your shoes are like F1 car tyres, and will affect your performance. "Experts may tell you different things, and it pays to experiment," says Sturdy. "I used to run in motion-control shoes because that's what all the experts told me I needed, but when I studied biomechanics I tried different things out for myself, and now I run in flats with no support."
"Make sure your shoes are as light as possible," says Sturdy. "Every few grams on the end of your leg can make a difference to how much energy you use."
Some other add-ons are crucial. "You need as much 'free' speed as possible," says Lumley. "Loose-fitting or wet clothing will weigh you down, so wear fitted, technical fabrics.
Wear sunglasses in summer, because they help relax your facial muscles - squinting can tense your face, which spreads to your neck and shoulders. Wear a hat with an elasticated rim so it doesn't pinch.
And beware jewellery - watches and rings can vibrate through your pedals and distract you. That can get a bit wearing in a long race."
The individual gains may be small but if you add them up, you'll find that a new PB is on the cards the next time you toe the line, even if you don't add go-faster stripes to your kit.