Sainz endures "toughest winter of his life" preparing for F1 2017

The 2017 cars will have significantly more downforce and will be much faster than the previous generation of single-seaters, making it much more demanding for the drivers, who have needed to gain muscle in order to prepare for the challenge.

Sainz says he has started using crossfit as part of his training programme, carrying out two-hour sessions before swimming for at least another 60 minutes.

The Toro Rosso driver admits he had never worked so hard before.

"In 2017 Formula 1 is taking a step forward," said Sainz. "They want cars to be much harder to drive physically so us drivers have to be up for it, and what we had in 2016 in terms of fitness is not good enough for 2017, so it's going to be a very tough year.

"I think without a doubt this has been the toughest winter since I'm in F1 and in my whole life actually, because I have never been in the physical shape I'll be in March for the first race.

"I discovered crossfit this year. It's more than crossfit, really, because I make it last the same as a Formula 1 race, so it's one-a-half/two hours with your heart rate at 180/190 and you don't stop doing things," he added.

Sainz says karting has also been an integral part of his training routine.

The Spaniard drives with a special helmet on, with an extra two kilos of lead attached to it in order to increase the g-forces generated in the corners.

Sainz, 22, reckons that while his age plays to his advantage, other drivers' experience with higher amounts of downforce will give them an edge.

"On the one hand I think that you are at your physical peak at 21-22 and so I think that's an advantage," he said. "But, on the other hand, drivers like Hamilton, Alonso or Raikkonen have the advantage that they have experienced similar g-forces during 2005, 2006 or 2007."

Neck the biggest challenge

Meanwhile, McLaren's rookie Stoffel Vandoorne conceded that strengthening the neck is one of the key aspects of 2017, given the much higher cornering speeds expected.

"I think the biggest challenge for the drivers in 2017 will be the g-forces on the neck," said Vandoorne. "Cornering speeds are predicted to be a lot higher – at least, they certainly feel a lot higher in the simulator.

"But for us to actually know how that will feel on the body is extremely difficult, because we can't accurately replicate those forces in the sim.

"That just means we have to do a lot of training over the winter to prepare for what we anticipate them to be.

"Actually, the neck is one of the hardest muscles on the body to train – it's fragile and easy to over-stress, so there's no one specific activity you can do to properly train it."