OBJECTIVE: To describe the functional cross-sectional area (FCSA) of the lumbar paraspinal muscles of professional fast bowlers in cricket and to investigate the nature of any muscle asymmetry. DESIGN: Descriptive cross-sectional between-groups study. SETTING: The England and Wales Cricket Board. PARTICIPANTS: Forty-six asymptomatic professional fast bowlers and 17 athletic controls. MAIN OUTCOME MEASUREMENTS: The magnetic resonance imaging of functional cross-sectional area (FCSA) of the lumbar paraspinal muscles, and the prevalence of asymmetry (greater than 10% difference in the FCSA between the dominant and nondominant side muscles). RESULTS: A relatively high percentage of fast bowlers had asymmetrically larger dominant side quadratus lumborum FCSAs at L1 (47%), L3 (41%), and L4 (47%). The nondominant side psoas FCSA was larger in fast bowlers at L5, and the dominant side multifidus FCSA was larger in both the fast bowlers at L3 to S1 and in the control subjects at L4 and L5. CONCLUSIONS: There was a higher prevalence of lumbar muscle asymmetry in the fast bowler group. Paraspinal muscle asymmetry was most prevalent in the quadratus lumborum of fast bowlers, and it was also evident in the lumbar multifidus in both groups of subjects. In both muscle groups, this was consistent with hypertrophy of the dominant side muscle. This study may be used to inform prospective studies of risk factors for low back injury in athletic males and enhance the development of more accurate models of stress production in the lumbar spine during fast bowling and other asymmetrical sports.
OBJECTIVE: To describe the functional cross-sectional area (FCSA) of the lumbar paraspinal muscles of professional fast bowlers in cricket and to investigate the nature of any muscle asymmetry. DESIGN: Descriptive cross-sectional between-groups study. SETTING: The England and Wales Cricket Board. PARTICIPANTS: Forty-six asymptomatic professional fast bowlers and 17 athletic controls. MAIN OUTCOME MEASUREMENTS: The magnetic resonance imaging of functional cross-sectional area (FCSA) of the lumbar paraspinal muscles, and the prevalence of asymmetry (greater than 10% difference in the FCSA between the dominant and nondominant side muscles). RESULTS: A relatively high percentage of fast bowlers had asymmetrically larger dominant side quadratus lumborum FCSAs at L1 (47%), L3 (41%), and L4 (47%). The nondominant side psoas FCSA was larger in fast bowlers at L5, and the dominant side multifidus FCSA was larger in both the fast bowlers at L3 to S1 and in the control subjects at L4 and L5. CONCLUSIONS: There was a higher prevalence of lumbar muscle asymmetry in the fast bowler group. Paraspinal muscle asymmetry was most prevalent in the quadratus lumborum of fast bowlers, and it was also evident in the lumbar multifidus in both groups of subjects. In both muscle groups, this was consistent with hypertrophy of the dominant side muscle. This study may be used to inform prospective studies of risk factors for low back injury in athletic males and enhance the development of more accurate models of stress production in the lumbar spine during fast bowling and other asymmetrical sports.