Lumbar Bone Mineral Adaptation: The Effect of Fast Bowling Technique in Adolescent Cricketers

Abstract

Introduction: Localized bone mineral density (BMD) adaptation of the lumbar spine, particularly on the contralateral side to the bowling arm, has been observed in elite male cricket fast bowlers. No study has investigated this in adolescents, or the role of fast bowling technique on lumbar BMD adaptation. This study aims to investigate lumbar BMD adaptation in adolescent cricket fast bowlers, and its relationship with fast bowling technique. Methods: Thirty-nine adolescent fast bowlers underwent anteroposterior dual x-ray absorptiometry scan of their lumbar spine. Hip, lumbopelvic and thoracolumbar joint kinematics, and vertical ground reaction kinetics were determined using three-dimensional motion capture and force plates. Significant partial (covariate: fat-free mass) and bivariate correlations of the technique parameters with whole lumbar (L1-L4) BMD and BMD asymmetry (L3 and L4) were advanced as candidate variables for multiple stepwise linear regression. Results: Adolescent fast bowlers demonstrated high lumbar Z-Scores (+1.0; 95% confidence interval [CI], 0.7-1.4) and significantly greater BMD on the contralateral side of L3 (9.0%; 95% CI, 5.8%-12.1%) and L4 (8.2%; 95% CI, 4.9%-11.5%). Maximum contralateral thoracolumbar rotation and maximum ipsilateral lumbopelvic rotation in the period between back foot contact and ball release (BR), as well as contralateral pelvic drop at front foot contact, were identified as predictors of L1 to L4 BMD, explaining 65% of the variation. Maximum ipsilateral lumbopelvic rotation between back foot contact and BR, as well as ipsilateral lumbopelvic rotation and contralateral thoracolumbar side flexion at BR, were predictors of lumbar asymmetry within L3 and L4. Conclusions: Thoracolumbar and lumbopelvic motion are implicated in the etiology of the unique lumbar bone adaptation observed in fast bowlers whereas vertical ground reaction force, independent of body mass, was not. This may further implicate the osteogenic potential of torsional rather than impact loading in exercise-induced adaptation.

Lumbar spine bone mineral adaptation: cricket fast bowlers versus controls

“… 9 This movement likely imparts a torsional force and high bone strain in the posterior elements of the vertebrae, 28 resulting in the osteogenic adaptation identified. Although external loads such as ground reaction forces showed no significant relationship to BMD, 9 it is possible that they contribute to the adaptation by influencing the internal loading of the lumbar spine. The unique adaptation of fast bowlers compared with other sporting and non-sporting controls was established previously in senior populations 8 29 and adolescents 9 and has been assessed longitudinally in this study for the first time.…”

“…The adaptation of the lumbar spine to fast bowling is driven by the forceful rotations of the thoracic and lumbar spine between back foot contact and ball release of the bowling action. 9 This movement likely imparts a torsional force and high bone strain in the posterior elements of the vertebrae, 28 resulting in the osteogenic adaptation identified. Although external loads such as ground reaction forces showed no significant relationship to BMD, 9 it is possible that they contribute to the adaptation by influencing the internal loading of the 8 29 and adolescents 9 and has been assessed longitudinally in this study for the first time.…”

“…Additionally, fast bowlers show substantial vertebral asymmetry with up to 15% and 18% greater BMD and BMC, respectively, found on the contralateral side to the bowling arm 8. This reflects the asymmetrical bowling action which involves extreme multi-planar trunk movements 9…”

“… 8 This reflects the asymmetrical bowling action which involves extreme multi-planar trunk movements. 9 …”

“…8 This reflects the asymmetrical bowling action which involves extreme multi-planar trunk movements. 9 Fast bowlers have the greatest prevalence of injury of all the playing roles in cricket, 10 with lumbar stress fracture (LSF), which occurs almost exclusively to fast bowlers, being the most prevalent injury in cricket. 10 Chronological age has been considered a lumbar bone stress injury (LBSI) risk factor, with studies identifying that younger bowlers are more likely to suffer LSF between 15 and 22 years of age.…”