Relationship between passive ankle dorsiflexion range, dynamic ankle dorsiflexion range and lower limb and trunk kinematics during the single-leg squat.

Background: Limited passive ankle dorsiflexion range has been associated with increased knee valgus during functional tasks. Increased knee valgus is considered a contributing factor for musculoskeletal disorders in the lower limb. There is conflicting evidence supporting this association. The extent of passive ankle dorsiflexion range is associated with dynamic ankle dorsiflexion range and the way how these variables are related to lower limb or trunk kinematics is unclear.

Research Question: What is the association between passive ankle dorsiflexion range or dynamic ankle dorsiflexion range with shank, thigh, pelvis or trunk movements during the single-leg squat?

Methods: This is a cross-sectional study with a convenience sample. Thirty uninjured participants performed the single-leg squat with their dominant limb. Ankle, shank, thigh, pelvis and trunk 3D kinematics were recorded. Passive ankle dorsiflexion range was assessed through the weight-bearing lunge test and the dynamic ankle dorsiflexion range was defined as the ankle dorsiflexion range of motion in the sagittal plane during the single-leg squat.

Results: Greater passive ankle dorsiflexion range was associated with smaller thigh internal rotation (r= -0.38). Greater dynamic ankle dorsiflexion range was associated with smaller trunk flexion (r = 0.59) and pelvis anteversion (r= -0.47). Passive ankle dorsiflexion range and dynamic ankle dorsiflexion range were not associated.

Significance: Greater passive ankle dorsiflexion range seems to be associated with a better lower limb alignment during the single-leg squat, while dynamic ankle dorsiflexion range seems to reflect different lower limb and trunk kinematic strategies.