By Robin Hodgetts

England all-rounder Flintoff will be required to put his body on the line

England's tour of India is just the start of a gruelling schedule ahead of the Ashes and 2007 World Cup.

The side can expect to play in every one of the next 20 months and coach Duncan Fletcher is worried about "player burnout".

But what does this well-worn sporting phrase really mean?

And how much of a threat is burnout anyway?

BBC Sport asked former England cricket physio Wayne Morton to run through the issues.

Professional sport is all about balancing the three Ps and burnout occurs when deficiencies in an athlete's physical, physiological or psychological state prevents them from performing to the level which everybody expects.

It's too simplistic to just attribute burnout to the physical side.

International cricket has become a continuous year-round game. On tour, schedules often only allow for playing days, practice days or travel days with only a short turnaround in between.

England fixtures in 2006

Players are expected to perform at the highest level and roll from one competition to the next without a suitable respite, both physical and mental.

It's important for players to recharge all of their batteries so they get a sensation of looking forward to what's happening next, otherwise competitions like the Ashes and the World Cup tend to roll into one.

Rugby or football is an hour-and-a-half of intensity and then you are off, while Olympic athletes, for example, train and enter various competitions to build up for the big event.

The problem with cricket is there is no real cyclical schedule.

A game of cricket also lasts for seven-and-a-half hours. A fast bowler might have a seven-over spell which is incredibly demanding and takes an awful lot out of your body and powers of concentration.

Then they might be called back to bowl several more spells, maybe 35 overs a day. It might have been true 30 years ago that bowlers only concentrate when they bowl but now they have to be fantastic fielders and can't switch off.

An all-rounder such as Andrew Flintoff can be on the pitch for 90% of the game, depending on how well he bats and bowls.

If you keep playing, travelling and preparing for matches it tends to be a downward slope.

To get better you require technical practice and you require rest and if you take either of those out of the equation you weaken the sport.

It's a known fact that physical and mental fatigue does leave you open to more injuries.

So the fear is that you can be as fit as you want but the more you play, the more likely you are to get injured.

But it's not as simple as scrapping back-to-back Tests, for example.

If somebody is at their absolute peak of fitness and on top of their game, back-to-back Tests or even three in a row, although physically demanding, are not the overall drain that Duncan Fletcher is referring to.

Cricket as a sport has no real switch off period and that's why Fletcher is trying to get some longer gaps between series.