What did Lillee, Botham and Trueman have in common? Answer: They were all chuckers

Angus Fraser reports from Dubai, where he was initiated into the strange science of biomechanics as part of an ICC committee on illegal bowling

What do Fred Trueman, Dennis Lillee, Curtly Ambrose, Imran Khan, Richard Hadlee, and Ian Botham - not to mention an old has-been called Angus Fraser - have in common? Apparently, we all spent our entire cricket careers breaking one of cricket's most fundamental laws: what constitutes a legal delivery. We were all, to use the language of the game, chuckers.

What do Fred Trueman, Dennis Lillee, Curtly Ambrose, Imran Khan, Richard Hadlee, and Ian Botham - not to mention an old has-been called Angus Fraser - have in common? Apparently, we all spent our entire cricket careers breaking one of cricket's most fundamental laws: what constitutes a legal delivery. We were all, to use the language of the game, chuckers.

If the conclusion was a bit surreal, so were the surroundings when I came to it. I was sitting in a conference room at the Emirates Tower Hotel in Dubai. With me were five other former international cricketers - Michael Holding, Aravinda de Silva, Tim May, David Richardson and Tony Lewis - along with three boffins who are experts in biomechanics: Dr Marc Portus, Professor Bruce Elliott and Dr Paul Hurrion.

We had each been invited by the International Cricket Council to sit on a committee looking into the most contentious issue in the game today, that of illegal bowling actions. It was our job to make some sense of this controversial and complicated issue and make recommendations of what should be regarded as a legal delivery. On the screen in front of us we were watching the likes of Glenn McGrath, Shaun Pollock, Stephen Harmison and Allan Donald, and I have to say the first response of all six former players was one of admiration.

What could possibly be wrong with the actions of these wonderful bowlers? Each was high at the crease, and their arms appeared to be ramrod straight as they moved through the all-important 90-degree sector between the upper arm reaching horizontal and the moment of release. As we soon learned, there was quite a lot wrong.

Chucking, or throwing, has always been one of the most controversial issues in cricket. Traditionally, the laws stipulated that the bowling arm should not straighten - extend - while passing through the vital 90 degrees. And until technology allowed television cameras to highlight almost every movement of a bowler's arm, it was believed that most did not throw. Occasionally someone would be reported for chucking - Geoff Cope, Harold Rhodes and Ian Meckiff - but instances were rare.

But interest in the subject increased hugely in 1999 and 2000 when Muttiah Muralitharan, Shoaib Akhtar and Brett Lee were all reported by officials. Research followed, but the results startled everyone when the scientists showed there to be movement in the elbow of almost every bowler as his arm came over. This stung the ICC into action and levels of tolerance - acceptable levels of straightening - were introduced. These were set at five degrees for spinners, seven and a half for medium pacers, and 10 for fast bowlers.

However, while we watched the likes of McGrath, Pollock, Harmison and Donald, we quickly realised that the levels were far too low. All those bowlers possessed actions any youngster would be wise to copy, we thought, yet their bowling arms were nowhere near as straight as we anticipated. Sitting mesmerised, we listened to an expert in biomechanics state the results of his research. "On this delivery the bowler's arm has straightened by 11 degrees," Dr Portus said. "On this one it straightened by eight; and on this it was 10."

We looked at each other in disbelief. Holding asked me whether I could see 10 degrees of movement after one delivery? I shrugged my shoulders, shook my head and said: "No".

We were then taken from a match situation, where there can be a three- or four-degree chance of error in the readings - it is difficult to identify the exact centre of a player's shoulder, elbow and wrist when he is wearing a long-sleeved shirt - to the laboratory, where biomechanics is accurate to within one degree. Here a group of first-class bowlers bowled with their shirts off, and with their arms, shoulders and torso covered with strategically placed reflective markers.

Bowlers have to take one of these tests if they are reported by an official and they have to pass it to continue with their career. In a laboratory the cricketer is filmed from every angle and coaches with international experience are present to ensure that the bowler is performing at the same intensity as he does in a game. For a fast bowler this means that he has to bowl at 95 per cent of the speed he has recorded in a match.

One would have thought a near perfect analysis of a bowler's arm would clarify the situation. It did not. If anything it made life more confusing. It would be easy if the elbow of a bowler moved in just one plane. But it does not. Loose elbows, and there seem an awful lot in bowlers, allow the joint to hyper-extend - move backwards past 180 degrees - as well as adduct and abduct - move sideways. Once again we sat flabbergasted, watching a projector screen as the results of these tests were relayed to us.

After watching one bowler's action, and noticing that something was not quite right, we asked Dr Portus to explain what was going on? He said: "This bowler straightens his arm by 11 degrees, hyper-extends by seven degrees and adducts by eight." Scratching our heads, we all burst out laughing.

It is this sort of movement which makes the action of Pakistan's Shoaib Akhtar appear far more suspect than it actually is. After a lengthy chat we decided it would be wrong to ban a bowler if his elbow hyper-extended, abducted or adducted. These are in voluntary movements, caused by the force of the arm as it comes over, and suspending a player for something like this - even though it gives him an advantage - would be hard to defend if the player took legal action.

Information on spin bowling was presented by Dr Hurrion, a scientist from England, who had been asked by the ICC to study his subject during September's Champions Trophy. The results again took us by surprise even though spinners generally kept their elbows straighter than pacemen. But they were still way above the five-degree level previously set by the ICC.

Harbhajan Singh, the Indian off-spinner, was found to have 12 degrees of movement in his elbow whilst Ashley Giles was around the five-degree mark. But the most remarkable fact was that Dr Hurrion's research found just one bowler who did not straighten his arm at all. Ramnaresh Sarwan's occasional leg-spin could hardly be described as front-line but the West Indian's right arm remained set at around 166/167 degrees throughout his action.

The bowling arms of most spinners are under less stress than the fast men, but it was agreed that the tolerance level should be the same for every type of bowler. To differentiate would over-complicate matters. For instance, which tolerance level would apply for a fast bowler bowling cutters - spinners.

We delayed the biggest decision until last but after a great deal of deliberation it was decided that an acceptable level of elbow extension for a bowler should be set at 15 degrees. Many will feel that by allowing this the ICC are legalising throwing. They are not. All the information and opinion collected, along with the fact that it is almost impossible to see the arm straighten with the naked eye until it reaches this angle, points to 15 degrees.

Policing it will be difficult, and this is why the ICC will occasionally send appointed bowling experts to matches to identify bowlers with suspected illegal actions. But there is little anyone can do about a bowler who throws in the odd delivery, which might have 20-25 degrees of extension. If he is reported, the chances are he will then be able to go back to his stock action and pass the laboratory test. Thankfully, these bowlers are rare and most honestly go about their business with an arm that is not and never will be straight.