Is bowling workload a risk factor for injury to Australian junior cricket fast bowlers?

Objectives: To examine whether bowling workload is a risk factor for overuse injury to Australian junior cricket fast bowlers and to evaluate the appropriateness of current bowling workload guidelines. Methods: Forty four male fast bowlers ( mean ( standard deviation) age 14.7 (1.4) years) were monitored prospectively over the 2002 - 2003 season. Bowlers completed a daily diary to record bowling workloads and self reported injuries, which were validated by a physiotherapist. Bowling workload prior to the first injury ( for those bowlers who were injured) was compared to workload across the whole season for uninjured bowlers. Results: Eleven (25%) bowlers reported an overuse-type injury, with seven of these sustaining a back injury. Injured bowlers had been bowling significantly more frequently than uninjured bowlers ( median number of days since the previous bowling day: 3.2 v 3.9 days, Mann-Whitney U = 105.0, p = 0.038). Compared with bowlers with an average of >= 3.5 rest days between bowling, bowlers with an average of,3.5 rest days were at a significantly increased risk of injury ( risk ratio (RR) = 3.1, 95% confidence interval (CI) 1.1 to 8.9). There were also trends towards an increased risk of injury for those who bowled an average of >= 2.5 days per week ( RR = 2.5, 95% CI 0.9 to 7.4) or >= 50 deliveries per day ( RR = 2.0, 95% CI 0.7 to 5.4). Conclusions: This study has identified high bowling workload as a risk factor for overuse injury to junior fast bowlers. Continued research is required to provide scientific evidence for bowling workload guidelines that are age-specific for junior fast bowlers.