Effect of Body-Borne Load on Lateral Trunk Flexion and Its Relation to Knee Abduction Biomechanics During a Single-Leg Cut

Body-borne load reportedly increases incidence of military-related knee injury by altering trunk and lower limb biomechanics. This investigation determined whether body-borne load impacts lateral trunk flexion during a single-leg cut, and whether greater lateral trunk flexion exaggerates knee abduction biomechanics. Thirty-six participants had trunk and knee biomechanics quantified during a single-leg cut with four body-borne loads (20, 25, 30 and 35 kg). To evaluate the impact of load on lateral trunk flexion and its relation with knee abduction biomechanics, peak stance lateral trunk flexion was submitted to a linear mixed model with load (20, 25, 30, and 35 kg) and sex (male, female) as fixed effects, and dominant limb peak stance knee abduction joint angle and moment considered as covariates. During the cut, there was a significant sex by load interaction for peak stance lateral trunk flexion ( p = 0.038), and peak stance lateral trunk flexion angle exhibited a significant association with peak stance knee abduction angle ( p < 0.001) and moment ( p = 0.014). Adopting lateral trunk flexion during loaded single-leg cuts may increase knee biomechanics related to ACL injury, but adding load only decreased lateral trunk flexion for female participants and did not further exaggerate knee abduction biomechanics.