Ankle dorsiflexion range of motion and trunk muscle endurance are not associated with hip and knee kinematics during the forward step-down test in CrossFit ® practitioners

Purpose CrossFit® (CF) is a high-intensity training method with a large number of practitioners, having an injury prevalence similar to other sports. Although excessive dynamic knee valgus is related to several injuries and associated with the trunk muscles’ endurance and dorsiflexion range of motion (DF-ROM), no study has evaluated these parameters in CF practitioners. The aim of the study was to investigate the association between lower limb alignment during the step-down test, DF-ROM and lateral trunk muscle endurance in CrossFit® (CF) practitioners. Methods Forty-two CF practitioners performed the following tests on both limbs: (i) DF-ROM with the weight-bearing lunge test; (ii) knee frontal plane projection angle (FPPA) and hip adduction (hip ADD) ankle during the forward step-down test; (iii) trunk lateral flexors’ endurance with the side plank test. Results No significant associations were found between knee FPPA and DF-ROM in both limbs (preferred: r = 0.192; p = 0.230; non-preferred: r = 0.089; p = 0.581) or side plank time (preferred: r = 0.086; p = 0.594; non-preferred: r = 0.248; p = 0.117). Moreover, no significant associations were found between hip ADD and DF-ROM in both limbs (preferred: r = 0.005; p = 0.975; non-preferred: r = 0.175; p = 0.275) or side plank time (preferred : r = – 0.134; p = 0.403; non-preferred: r = 0. 171; p = 0.284). Conclusion Lateral trunk flexors’ endurance and ankle dorsiflexion range of motion are not associated with hip and knee kinematics during the forward step-down test in CrossFit®.