Prediction and prevention of lower limb injuries and attrition in army recruits

Research output: ThesisDoctoral Thesis

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Abstract

Two cluster-randornised controlled trials and three cohort studies nested within those trials were conducted to investigate the effects of pre-exercise stretching on risk of injury, and to identify predictors of injury and attrition risk in arrny recruits. Based on the results of the latter two cohort studies, a study of the predictive validity of aerobic fitness scores for predicting injury and attrition was also conducted, followed by a study of the cost-effectiveness of screening applicants on the basis of these fitness scores. The effect of pre-exercise calf muscle stretching on risk of selected injuries was investigated in 1093 male army recruits undertaking 12 weeks of intensive training (Study I). Prior to training, ankle dorsiflexion range was measured and subjects were randomly allocated to stretch and control groups in clusters of approximately 40 recruits. The stretch group stretched calf muscles under supervision prior to all intense exercise. The control group stretched upper limb muscles instead. The incidence of five types of lower limb injury was monitored. 48 injuries were recorded during the training period. No effect of stretching on injury risk was found (Hazard Ratio [HR] = 0.92, 95% CI 0.52 to 1.61) and there was no significant interaction between stretching and ankle dorsiflexion range in determining injury risk (Wald statistic = 2.82; df = 1; p = 0.09). Ankle dorsiflexion range was a significant predictor of injury (p = 0.03), particularly ankle sprain (p < 0.01). The relative injury risk (RIR) associated with the lowest ankle dorsiflexion range (34 degrees) compared to that associated with the highest ankle dorsiflexion range (58 degrees) was 7.6 (95% CI 1.2 to 46.9). The relative ankle sprain risk associated with the lowest ankle dorsiflexion range compared to that associated with the highest ankle dorsiflexion range was 31.2 (95% CI 2.5 to 386.4). Ankle dorsiflexion range explained 0.4% of the observed variability among subjects in injury risk, and 1.4% of the observed variability in risk of ankle sprain. A second cluster-randomised trial was conducted to determine whether stretching of a range of key muscle groups could reduce the risk of suffering a broader range of injuries, during subsequent exercise (Study II). For this purpose, 1538 male armyrecruits were randomly allocated to stretch or control groups in clusters of approximately 40 recruits. During 12 weeks of training, both groups performed active warm-up exercises prior to physical training sessions. In addition, the stretch group performed one 20-second static stretch under supervision for each of six major leg muscle groups during every warm-up. The control group did not stretch. 333 lower limb injuries were recorded during the training period, including 214 soft-tissue injuries.
Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • Charles Sturt University
Supervisors/Advisors
  • Herbert, Rob, Co-Supervisor, External person
  • Towers, Philip, Principal Supervisor
  • Graham, Bruce, Principal Supervisor
Award date01 Jun 2002
Place of PublicationAustralia
Publisher
Publication statusPublished - 2002

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