Abstract
OBJECTIVE: The purpose of this study was to investigate the relationship between bilateral lower extremity explosive strength asymmetry and non-contact low back injuries in mine rescue workers, a specialized occupational group. METHODS: A single-leg countermovement jump (SLCMJ) test was performed on 101 rescue members who had participated in frontline rescue missions, using a force platform. The collected force platform data were used to calculate lower limb asymmetry. Injury incidence was measured by recording all non-contact low back injuries occurring during routine training or rescue operations over a 12-month follow-up period. Jump metrics (including eccentric peak force, vertical velocity at takeoff, peak takeoff acceleration, and takeoff peak force) associated with non-contact low back injuries were identified through Poisson regression analysis, and the optimal threshold for predicting injuries was determined using the receiver operating characteristic (ROC) curve. RESULTS: Bilateral takeoff peak force asymmetry significantly increased the risk of non-contact low back injury. Each 1% increase in asymmetry raised the injury risk by 18.5% (RR = 1.185, 95% CI: 1.091-1.288, p < 0.001), equivalent to an absolute increase of 3.2% (RD = 0.032, 95% CI: 0.009-0.056). Using the optimal threshold of 7.05% for risk stratification, rescue workers in the high-risk group had a 3.6 times higher injury risk than the low-risk group (RR = 3.64, 95% CI: 1.353-9.832, p = 0.011), corresponding to an absolute risk difference of 24.1% (RD = 0.241, 95% CI: 0.073-0.409). CONCLUSION: The interlimb asymmetry measured during the single-leg countermovement jump can be used to predict the risk of non-contact low back injuries in mine rescue workers over a 12-month follow-up period. Particular emphasis should be placed on the interlimb asymmetry of takeoff peak force.