Carlos Sainz claims Formula 1's current technical regulations are bad for the health of the drivers.
The Ferrari driver says he and some of his rivals are worried about the long-term effect severe 'porpoising' caused by the new ground effect cars will have on their bodies.
"I don't need expert advice to know that ten years like this will be difficult and you will have to work a lot on mobility and flexibility," the Spaniard is quoted by La Gazzetta dello Sport.
"I did my usual checks - on the back, around the neck - and this year I'm stiffer everywhere."
He says it is now up to F1's authorities to investigate the extent of the problem.
"It's about understanding how much a driver has to pay for his Formula 1 car with his back and his health with this kind of automotive philosophy," said Sainz, the 27-year-old son of the world rallying great.
"We have to open up the debate on that. I think the regulations are great - they are doing what we needed to race. But is it necessary to run so stiff for our necks and our back?"
