Biomechanics of the double rocker sole shoe: gait kinematics and kinetics

Abstract

This paper reports the kinematic and kinetic changes in gait with bilateral double rocker sole shoe modifications. Three-dimensional motion analysis techniques were used to evaluate gait characteristics (temporal-spatial, kinematic, and kinetic measures) of forty (40) subjects while wearing baseline and double rocker sole shoes. Walking speed was unchanged by the double rocker modification. Sagittal plane motions showed significant change at the pelvis, hip, knee, and ankle. (p = 0.01). The toe-only rocker consistently resulted in increase in posterior pelvic tilt (p =0.01). Kinetic changes were observed at the hip in the sagittal and transverse planes, and at the knee and ankle in the sagittal planes. Changes in pelvic tilt and hip rotation were hypothesized to result from feelings of imbalance during ambulation with the double rocker sole shoe.

Figure 1

Baseline (top) and Double Rocker (bottom) shoes

Figure 2

Sagittal plane kinematics of R pelvis, hip, knee, and ankle for Baseline and Rocker shoes (mean curve with upper and lower 95% pointwise confidence bands). Positive values correspond to anterior tilt (pelvis) and joint flexion (all other joints). Points of significant difference are marked on abscissa; magnitudes of significant changes [degrees] from Baseline to Rocker are indicated.

Figure 3

Hip rotation and foot progression angle (right-side) for Baseline and Rocker shoes (mean curve with upper and lower 95% pointwise confidence bands). Positive values correspond to internal rotation. Points of significant difference are marked on abscissa; magnitudes of significant changes [degrees] from Baseline to Rocker are indicated.

Figure 4

Sagittal plane moments of R hip, knee, and ankle for Baseline and Rocker shoes (mean curve with upper and lower 95% pointwise confidence bands). Positive values correspond to extension demand moment (hip and knee) and plantarflexion demand moment (ankle). Points of significant difference are marked on abscissa; magnitudes of significant changes [Nm/kg] from Baseline to Rocker are indicated.

Figure 5

Transverse plane moments of R hip, knee, and ankle for Baseline and Rocker shoes (mean curve with upper and lower 95% pointwise confidence bands). Positive values correspond to internal rotation demand moment. Points of significant difference are marked on abscissa; magnitudes of significant changes [Nm/kg] from Baseline to Rocker are indicated.

Figure 6

Total joint power of R hip, knee, and ankle for Baseline and Rocker shoes (mean curve with upper and lower 95% pointwise confidence bands). Positive values correspond to power generation. Points of significant difference are marked on abscissa; magnitudes of significant changes [W/kg] from Baseline to Rocker are indicated.