Top fitness expert John Brewer, who has given advice to such stars as Alan Shearer and Darren Gough, says sportsmen and women cannot expect to fire on all cylinders if their body is not in the best possible shape.

"There is no substitute for talent and skill but if you don't underpin that ability, you can't produce it repeatedly," said Brewer. "It makes sense to look after your fitness."

Golfer Westwood and cricketer Flintoff have been criticised for being fat and not paying enough attention to fitness and diet.

Ability

Both men have bags of ability but there is a widespread feeling that they have yet to make the most of their talent.

"The role of fitness will change from one sport to another," said Brewer, who is head of Human Performance at the National Sports Centre at Lilleshall.

"It would be totally wrong to suggest that fitness is as important to golfers as it is to marathon runners.

"But anyone who has got to the top and stayed there must be fit. No sporting individual that I have come across has been poorer for being fitter."

Brewer certainly thinks Westwood would stand a better chance of winning his first Major if he devoted more time to his physical condition.

"Nick Faldo, who takes his fitness very seriously, maybe going through a bad patch at the moment but he has won more Majors than any other British player in modern times," said Brewer.

Perform

"Lee Westwood is a successful golfer but he hasn't won a Major yet. That is not to say that he cannot perform at a high level, but the difference between winning - and not winning - a Major is very, very small.

"If you look at cricket, the days where you can get away with being overweight and unfit are long gone.

"The current South African team have developed their fitness to such a degree that it is now comparable to that of the South African rugby players and footballers."

The fitter you are, the less injuries you are likely to have as well, says Brewer.

He thinks Flintoff's persistent back problems are more than likely connected to his weight.

"The root of the problem may be staring him in the face and has been well-documented recently," said Brewer. "If you are overweight you put extra stress on your body.

Wickets

"What Andrew Flintoff needs to be doing is not just making runs with the bat but taking wickets and being able to bowl regularly for his captain."

But, according to Brewer, there is more to fitness than just being in trim. Diet is also important.

"It is a bit like a Grand Prix car. If you don't put the right fuel in the tank, it won't perform," he said.