An investigation into the spinal kinematics and lower limb impacts during cricket fast bowling and their association with lower back pain.

Abstract

Cricket fast bowlers have been highlighted as having increased risk of injury when compared to the rest of the team. Lower back injury and more specifically, pain results in more time away from cricket than any other injury in the fast bowling population, with juniors displaying even greater risk compared with senior fast bowlers. Whilst lower back injury (confirmed musculoskeletal diagnoses, usually radiographically) in fast bowlers has been repeatedly investigated. Lower back pain (LBP), defined as pain resulting in time away from matchplay or training with or without a formal diagnosis, (highlighted to display a different relationship to injury) has received little attention in fast bowling literature. High bowling workloads (usually recorded in overs or days bowled) and the immature spine of junior fast bowlers have been highlighted as significantly increasing risk of injury. However, research regarding specific kinematic and kinetic risk factors requires further attention. Therefore, this study aimed to address current methodological limitations to investigate the association between spinal kinematics and lower limb impacts during fast bowling and risk of LBP in junior and senior fast bowlers. This study compares bowling kinematics and lower limb impacts in junior and senior fast bowlers and retrospective and prospective LBP risk, to provide additional insight into the clinical biomechanics of fast bowling. This study has shown inertial sensors and accelerometers are a valid (r>0.8 for 79% of variables, RMSEP = 0.3-1.5°) and reliable (ICC’s >0.8 and SEM<3.4g and 9°) method of analysing fast bowling lower limb impacts and spinal kinematics and may therefore be an acceptable alternative to current methodologies. Analysis of tibial impacts on different playing surfaces displayed larger impacts on outdoor artificial surfaces (26.6g) compared with grass (24.7g) and indoor rubber (22.0g) and wood (17.8g). Highlighting, large workloads on outdoor artificial surfaces may increase injury risk, with a wooden indoor surface more favourable. Retrospective and prospective LBP and injury data highlighted that senior fast bowlers with known spinal pathologies displayed four times greater risk of future LBP. However, this was not necessarily the case in junior bowlers. Results highlighted that peak accelerations at back-foot impact were higher in bowlers with no history of LBP, as well as bowlers that did not develop LBP in the follow-up season with differences between 8-10g seen in peak tibial acceleration. This may be a potential mechanism of reducing load at front-foot impact (which showed few notable differences between groups). Junior bowlers with a history of LBP displayed less contralateral thoracic rotation at back-foot impact and consequently a lower overall range. However, this trend was not displayed in senior bowlers. Senior bowlers, with either a history of LBP or that went on to develop LBP bowled with almost double lumbar extension (9° to 16°) resulting in a 12° increase in thoracolumbar extension at back-foot impact. Therefore, this study suggests that higher magnitudes of fast bowling impacts may not be synonymous with increased risk of LBP, however spinal kinematics at back-foot impact may provide some insight into bowlers’ risk of developing LBP. The effect of these recommendations on fast bowling performance was analysed through a correlation of impact and spinal kinematics with ball release speed. This highlighted that the recommendations to reduced risk of LBP are not likely to affect ball release speed, as only sacral loading rate at back foot impact and thoracic lateral flexion at FFI showed significant correlations with ball release speed (r=.521 and .629 respectively). Overall this study has demonstrated the application of novel technology applied to the live cricket fast bowling situation, overcoming limitations of previous methods. The method was valid, reliable and sensitive enough to determine significant differences in the spinal kinematics which were associated with LBP history or with developing LBP in the follow-up season and these were specific to junior and senior bowlers. These new insights will help to inform surveillance and coaching practices in the quest to reduce the injurious nature of fast bowling.