Is football bad for your health? An absurd question, on the face of it. Surely youthful muscle and sinew, hearts and lung can only benefit from chasing a ball around. And as for those happy few who make it to the Premier League of the professional game, they would appear to be cosseted like racehorses. Their exercise regimes are scientifically controlled, their diet prescribed - high in carbohydrates, low in fat and even lower in alcohol. Water rather than beer is now the traditional after-match tipple.

But how will they fare later in life? The latest evidence suggests that many will pay a price for their inflated salaries in the form of inflamed joints. Almost half of former top-flight pros are suffering from arthritis. One in three has had surgery and one in six is registered disabled, according to a Coventry University survey into the long-term health impact of professional football in the UK.

The Football Association is carrying out its own audit into the physical toll on players. By February next year, every injury which has kept a player out of training for 48 hours or more should have been registered. "Once the facts are known, we will be better able to develop prevention strategies," says Alan Hodson, head of the FA's medical education centre."

But surely today's professionals are fitter and better informed than their forerunners in the 60s, 70s and 80s? "That's true," says Hodson. "And if everything had stood still, the prevalence of injuries should have gone down. Unfortunately, though, the demands of the game at the top level have gone up."

Nobody is more aware of those demands than managers, under pressure from fans and chairmen to get results at all costs. They want their best players out on the park, whether they are carrying injuries or not.

"I know of one player who took two painkilling injections every match between the end of December and the end of the season last May," says sports researcher Martin Roderick of Leicester University. "Others take anti-inflammatory and painkilling tablets as if they were Smarties. Professional sport isn't conducive to good health, and the career of a footballer is usually a catalogue of injuries."

Roderick is co-author, with Dr Ivan Waddington, of Managing Injuries in Professional Football - a report on the role of club doctors and physiotherapists, commissioned by the Professional Footballers' Association. "There are more chartered physios and full-time doctors than there used to be," he says. "But half the physios in football aren't qualified for a job in the NHS. Their appointment is a gift of the manager."

Indeed, the great Liverpool sides of the 70s and 80s were run by a dynasty that might have been known as the Order of the Magic Sponge. Bill Shankly's successor was his physiotherapist, Bob Paisley. He in turn was succeeded by his physio, Joe Fagin. Only comparatively recently did Liverpool appoint a chartered physiotherapist, Mark Leather. He has since moved on to Blackburn Rovers, allegedly after an argument over the state of Michael Owen's hamstring with the manager, Gerard Houllier.

Houllier, though, appears mild-mannered compared to some of the tyrants of the touchline who have controlled English clubs in the past. Perhaps the most abrasive of all was Brian Clough - to many the greatest manager England never had, but not a man to offer sympathy to the injured. "If you weren't fit enough to be in the side, you might as well have been in Australia as far as he was concerned," recalls Alan Durban, a member of Cloughie's Derby County side which, incredibly, won the championship in 1972 with a squad of just 16 players.

Now 59, Durban is relaxing after playing tennis at Telford Racquet Centre in Shropshire, where he was general manager until recently. Although he retains a good eye for a ball and excellent positional sense, he moves around the court with evident discomfort.

Two years ago, he had a hip replacement operation. "I need to hang on to the banisters to get downstairs in the morning because my joints aren't too good," he says.

Reluctantly, he concedes that football took its toll. "I had a few cortisone injections because I was fearful of losing my place. In those days you could only earn a decent wage through appearance money in a successful team."

Derby's quagmire of a pitch made twists and strains more likely. Regular tanglings with uncompromising opponents like Norman Hunter of Leeds, Chelsea's Ron "Chopper" Harris and Tommy Smith of Liverpool put at risk any bone from the knee down.

Smith was arguably the craggiest defender of his generation. Now in his mid-50s, he became the most high-profile footballing victim of arthritis when his disability benefit was drastically reduced after he took a demonstration penalty before the 1996 FA Cup Final. "I was drugged to the eyeballs," he later admitted, this proud former "iron man" who had to go before a DSS tribunal and tell how he could no longer get dressed, tie his shoelaces or even get on and off the toilet without the help of his wife.

In Smith's day, cortisone was the routine way of masking pain before a match. "Some players had over 20 injections in the same joint," says Andy Turner, who did the survey of 284 former professionals in the Coventry University study. Turner, 38, had to give up playing local football nine years ago after developing osteoarthritis in one of his knees.

Reasearch from Scandinavia, he says, suggests that amateur footballers are even more at risk. They are less fit to start with, have lower skill levels and hence less awareness of how to avoid crude tackles. What's more, as Turner puts it, "They don't fancy spending Saturday night in casualty getting immediate treatment while their mates are out having a few pints."

He is now engaged in follow-up qualitative research with the old pros who responded to his initial survey. "One of them told me that if he could get hold of the doctor who administered cortisone, he'd strangle him." Why? Because the hormone damages tissue if taken to excess. The FA now has guidelines on the number of injections that can be administered: no more than three.

But do the clubs take any notice? Dr Roger Wolman, consultant in rheumatology and sports medicine at the Royal National Orthopaedic Hospital in Stanmore, Middlesex, is doubtful. "I have a feeling that the attitude of the clubs hasn't really changed," he says.

He sees at least one former professional footballer every month. "It's a sport that involves twisting on a weight-bearing joint. So there is always a risk of ligament or meniscus (cartilage) damage which makes them more prone to osteoarthritis in later life."

So how can the risks be reduced? "Lots of conditioning exercises to strengthen the muscles that support the knee - leg presses, exercise bikes, swimming. And take the advice of an experienced clinician after an injury."

Leicester University's researchers praise Sheffield Wednesday as the most enlightened club when it came to giving its players time to recover. At the end of last season, alas, Wednesday were relegated from the Premier League.