Reduced nondominant lumbar multifidi cross-sectional area is a precursor of low back injury in cricket fast bowlers.

Asymmetry in the lumbar multifidi muscle (LM) cross-sectional area (CSA) is associated with low back injury. The aim of this prospective cohort study was to investigate the symmetry of the CSA of LM at L3, L4, and L5, in the context of simultaneous injury monitoring. Injury free, male, right-handed cricket fast bowlers playing at a nonprofessional level participated in this study. LM CSA at L3, L4, and L5 vertebral levels was measured through the use of ultrasound imaging in prone. The primary outcome measure of the study was the incidence of an injury during a cricket season of eight-month duration. Twenty-six fast bowlers (aged 21.8 ± 1.8 years) participated. No difference was found between the nondominant and the dominant LM CSA among injury free bowlers (P>.05). However, in bowlers who sustained a lower back injury during the cricket season, the nondominant CSA at L3 (nondominant median 5.80 cm2 , range 3.69 cm2 ; dominant median 7.38 cm2 , range 2.61 cm2 ; P=.04) and L5 (nondominant median 6.94 cm2 , range 2.10 cm2 ; dominant median 7.38 cm2 , range 3.54 cm2 ; P=.04) is smaller compared to the dominant side. These findings may indicate that a side-to-side difference in LM CSA may be a precursor of injury.