Table 1 Biomechanical variables of interest between footwear and barefoot conditions

Peak KFM (Nm/kg)

Peak external knee flexion moment during stance. Positive values indicate higher KFM.

Stance time (s)

Time of stance from initial contact (> 20 N) until toe off (< 20 N).

Sagittal plane knee-GRF lever arm (mm)

Perpendicular distance between GRF and knee joint centre in laboratory sagittal plane. Calculated at time of peak KFM.

Sagittal plane resultant GRF magnitude (BW)

Resultant magnitude of the sagittal plane GRF calculated at time of peak KFM. Force was converted from Newton’s to bodyweight (BW).

Knee flexion angle (°)

Sagittal plane knee flexion angle at time of peak KFM. Positive values indicate knee flexion.

Ankle dorsiflexion angle (°)

Sagittal plane ankle dorsiflexion angle at time of peak KFM. Positive values indicate dorsiflexion.

Hip flexion angle (°)

Sagittal plane hip flexion angle at time of peak KFM. Positive values indicate hip flexion.

Knee flexion excursion (°)

Difference between the knee flexion angle at initial contact and peak across stance phase.

Knee flexion at initial contact (°)

Knee flexion angle at initial contact of force plate. Initial contact designated as time when GRF > 20 N.