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Over half of ACL injuries in rugby in our analysis resulted from a contact mechanism. For non-contact injuries, lower knee flexion angles and heel-first ground contact in a side-stepping manoeuvre were associated with ACL injury.

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Objective: In this study, the injury incidence and association with type and volume of training in international rowers were described. Design: A prospective cohort design was used over a 12-month period. Patients: 20 international rowers who were competing as part of the Irish Amateur Rowing Union squad system. Methods: The rowers were interviewed monthly, and data were collected regarding their training and competition exposure as well as their injury experience. Results: A mean injury rate of 3.67 per 1000 exposure hours was reported with a total of 44 injuries reported in a 12-month period. The mean number of injuries sustained per athlete was 2.2 (1.24) over the 12-month period. The area where the greatest number of injuries were reported was the lumbar spine (31.82% of total injuries, 95% CI 20 to 50) ( fig 2) followed by the knee (15.91% of total injuries, 95% CI 10 to 30) and the cervical spine (11.36% of total injuries, 95% CI 5 to 24). Half of the injuries (22 injuries, 50% of total reported injuries) were to the spine (x 2 = 30.8, df = 9, p = 0.0003). Ergometer training load was the most significantly associated with injury risk (r = 0.68, p = 0.01). Conclusion: International rowers are at higher risk of injury than most non-contact sports and some contact sports. The high risk of lumbar spine injury and the significant association of high volume of ergometer training merit further research to reduce time and competition lost to injury.

Fracture toughness is important for any material, but to date there have been few investigations of this mechanical property in soft mammalian tissues. This paper presents new data on porcine muscle tissue and a detailed analysis of all previous work. The conclusion is that, in most cases, fracture toughness has not in fact been measured for these tissues. Reanalysis of the previous work shows that failure of the test specimens generally occurred at the material's ultimate strength, implying that no information about toughness can be obtained from the results. This finding applied to work on cartilage, artificial neocartilage, muscle and the TMJ disc. Our own data, which was also found to be invalid, gave measured fracture toughness values which were highly variable and showed a strong dependence on the crack growth increment. The net-section failure stress and failure energy were relatively constant in large specimens, independent of crack length, whilst for smaller specimens they showed a strong size effect. These findings are explained by the fact that the process zone size, estimated here using the critical distance parameter L, was similar to, or larger than, critical specimen dimensions (crack length and specimen width). Whilst this analysis casts doubt on much of the published literature, a useful finding is that soft tissues are highly tolerant of defects, able to withstand the presence of cracks several millimetres in length without significant loss of strength.