By Sarah Holt

"There is no other sport as physically demanding as Formula One," says Renault driver Heikki Kovalainen.

Really? Isn't it the multi-million pound car that does all the hard work with its 700bhp engine and state-of-the-art aerodynamics, while the driver simply guides it round the track like a jockey?

Kovalainen and Fisichella at a pre-season training session

"A lot of people think all the drivers do is sit in the car, put the throttle down and whichever car has more power that's who wins," says the Finn, 25.

But it is not quite as simple as that.

Formula One drivers need a unique combination of power, aerobic fitness and mental strength to handle speeds of more than 200mph and forces of more than 5G for 90 minutes at a time.

BBC Sport joined Kovalainen and his personal trainer Gabriele Polcari for a training session to find out why the anatomy of an F1 driver is as precisely engineered as the tools of their trade.

"My neck is too big for my body, isn't it?" Kovalainen, who is 1.70m (5ft 7in) tall, asks half-jokingly. "It measures 16-and-a-half inches so if I bought a normal shirt the sleeves would be near my fingers!"

Despite developing outsize proportions, building up the neck muscles is one of the most important aspects of an F1 driver's training.

When they hurtle into corners, the G-force makes their heads weigh around five times their normal weight - meaning the crash helmet alone weighs 7kg.

RACE WEEK ROUTINE Monday: Neck training Tuesday: Aerobic training Wednesday: Travel day Thursday: Stretching or treatment Friday: Rest day or hotel gym Saturday: Breathing exercises Sunday: Recovery massage and stretching

"That puts a big stress on your neck," says Kovalainen. "Lap after lap of that weight and your neck starts to wear out."

Supporting the head and stopping it lurching from side to side requires beefed up neck and back muscles.

McLaren drivers can train using a helmet attached to pulleys which pull the neck from different angles.

Renault use manual resistance techniques specifically designed for each circuit - Kovalainen will sit in his helmet and Polcari will push his head in the same sequence of directions as the track.

"We sit for an hour-and-a-half and go through each turn," says Polcari.

"The neck and the aerobic condition are the two main facets for any F1 driver, so that is what we concentrate on."

"A good way to describe how fit we need to be is to say that each race we run a marathon but we cannot afford to get tired," explains Kovalainen.

The Finn has a resting heart beat of 58 beats per minute but his average rate during the race rises to 170 - the same as a marathon runner - before the adrenaline pushes it even higher.

"At the start, when I'm looking at the lights, I'm not moving a single muscle, but my heart rate is 185-90, which is close to my maximum," adds Kovalainen.

Drivers operate in cramped and constricted conditions, strapped in around the crotch and chest, amid sweltering temperatures and deafening engine noise.

"The body is constantly sweating and sometimes it's difficult to breathe," says Kovalainen. "But it's something we are all used to."

Kovalainen shows our reporter how to improve her wrist strength though not with the same weights

At this season's Malaysian Grand Prix, where it was 40C heat and 80% humidity, "some of the drivers jumped out of their cars and almost passed out," Polcari recalls.

Drivers prepare for these rigours with intensive training during the close season from November to March.

Then Kovalainen trains six days a week, twice a day; weights in the morning and aerobic exercise in the afternoon.

The aerobic conditioning is focused on running, cross-training and cycling where Kovalainen either maintains a specific heart rate for 90 minutes or pushes it through peaks and troughs.

"There is no other sport, apart from the marathon, where an athlete has their heart rate so high for such a long time," says Polcari.

Kovalainen will get to make a true comparison for himself in November when he runs the New York Marathon, as part of his winter training.

"Balance is extremely important in F1," says Kovalainen. "You feel everything through your ass."

Steering such a powerful machine through the twists and turns of a track uses the core of the body; the abdomen, arms and back.

The whole upper body is tuned using free weights and chest presses so that it is stable enough to cope with the physical stress of the g-forces.

"We don't use heavy weights just pure power work as we are focused on building up strength and resistance," says Kovalainen.

"Drivers do need strong arms, but not as muscley as boxers as then they would have too much bulk weight," explains Polcari. "They need light, strong muscles."

A picture of concentration - Kovalainen works his core and arms in the gym

To get his arms used to the stress of holding a steering wheel for long periods during a race, Kovalainen strengthens them by balancing on top of an exercise ball and holding a 5kg weight in front of him.

Polcari then at intervals directs him to turn the weight left, right or back to the middle; he says: "I'm asking him for effort, concentration and reaction."

Kovalainen also works on improving his grip by lifting 3kg weights using slight turns of his wrist.

"Can you see the veins?" the Finn asks as the lactic acid starts to burn. "I'm preparing my forearms so in the race they know they need to be this strong again."

"My legs are very slim," says Kovalainen. "Maybe they need to be a little bit stronger but not too muscley.

"The pedals in F1 cars are quite stiff, they're not easy like a road car, and the braking power is generated through the entire leg."

Kovalainen builds up his leg strength by holding up 90kg weights on a press machine with his legs and then quickly releasing and returning either the left or right foot depending on Polcari's command.

"I can't let the weights fall," explains Kovalainen. "I'm pushing and holding and combining reaction with strength."

"We always try and involve the brain in training because in F1 we have to keep the brain running until the last straight," says Kovalainen.

"We cannot lose concentration, we have to talk to the team on the radio and, if you are well prepared physically, then there will a bit left in reserve for your brain to cope.

You have to be ready for something that is coming but you don't know when or where Heikki Kovalainen

"The most important job for an F1 driver is to drive your pants off in the car, 110%, but you also need a good memory and awareness to communicate to the mechanics and engineers what the car is doing."

Kovalainen practises keeping his brain alert, and honing his hand-eye coordination, by using a batak reaction board, where the aim is to hit as many randomly-lit lights in 60 seconds as possible.

He tells me 60 lights for a first go is OK - I manage 47. His friend, a fighter pilot in the Finnish air force, hits 101. Kovalainen hits 121. Why is he so good?

"You have be alert for different situations in F1," says Kovalainen. "You have to be ready for something that is coming but you don't know when or where.

"Our job is to drive on average one-and-a-half days a week throughout the year, but the rest of the time is spent preparing for that.

"If we were not athletes, we'd just turn up and race, but if you are not physically and mentally prepared you cannot be successful in Formula One."