Michael Owen's problem with a recurrent hamstring injury is reflected in a research paper published yesterday which shows that muscle strain is the most common injury experienced by professional soccer players. The study confirms that professional footballers are at high risk of occupational injury compared to other sports.

The Liverpool and England player has had five separate hamstring strains since April 1999 - the new study found that 66 per cent of recurrent injuries involved muscle strains, of which most were in the muscles of the thigh, including the hamstring.

The research, published in the British Journal of Sports Medicine, looked at the number and type of injuries sustained by players at 91 professional football clubs in England during the period July 1997 to May 1999.

A total of 6030 injuries were audited over the two seasons, giving an average of 1.3 injuries per player per season. Injuries caused an average of 24 days absence from play. Eighty per cent of injuries caused players to miss at least one match, while the average number of matches missed was four.

Four out of every 10 injuries were caused by tackling and collisions. A third occurred during training and these gradually decreased as the season progressed.

Competitive injuries were at their highest in August and fell dramatically at the end of the season in April and May.

The authors of the study, who included representatives of the FA Medical Education Centre at Lilleshall, suggest that this is because players have not reached optimal levels of fitness at the beginning of the season. They recommend that the content of pre-season training and fitness maintenance during the closed season be revised to avoid this.

The study results confirm previous reports of the high risk of injury in professional football, which is greater than that seen in many other sports.

About 90 per cent of the injuries reported in the study were located in the lower limb, with thigh injuries more common than ankle or knee problems.

The possibility that fatigue - to both brain and muscle - is a factor in injuries is supported by the finding that the greatest number of injuries occurred in the two 15-minute periods towards the end of both halves.

Muscle fatigue has been identified as a factor in football injuries which at least partly explains the greater injury incidence seen in the second half of competitive matches.

A worrying aspect of the research is the finding that major injuries are preceded by minor injuries of the same type and same location. On the positive side, only one per cent of injuries were to the head, which correlates exactly with the one per cent of injuries caused by use of the elbow.

The authors recommend that further studies look at the factors contributing to the pattern of injuries relative to the time they occur in a match and that clubs re-examine their rehabilitation protocols.