Materials & Methods

METHODS

In order to analyze step length, stride length, and stride rate under different heel height conditions, one volunteer was recruited to perform three walks captured by video. A stride was defined as the length between heelstrike of one foot, to the second heelstrike of the same foot. A step was defined as the length between toe-off of one foot, to heelstrike of the other foot. Stride rate refers to stride per second, calculated from frames per second.

The 21-year-old female subject is 165.1 cm tall, and has a body mass of 58.97 kg. The subject describes herself as moderately active and has no history of lower extremity injuries, nor gait abnormalities. The subject does not describe herself as a regular high heel-wearer, wearing them an average of 3 times per year for formal occasions only. Before beginning the recordings, neon green circular adhesive markers were secured on the anatomical landmarks of interest for the analysis: the greater trochanter of the hip, the lateral epicondyle of the knee, and the lateral malleolus of the ankle. These markers were only placed on the right side of the subject’s body, as this side was visible in the videos taken.

The videos were recorded using an iPhone 12 Pro (model number MGK23LL/A) in front of Wake Forest University’s Worrell Professional Center’s Health and Exercise Science department building. The subject walked across a level concrete sidewalk in 3 different pairs of shoes: firstly, a pair of tennis shoes to provide a baseline/control gait cycle, then a low pair of heels (6.985 cm high, closed toe), then a higher pair of heels (10.16 cm high, open toe with ankle strap). The iPhone was leveled using the “Bubble Level” app from the Apple App Store, and was placed approximately 3.6 m away from where the subject walked. The software program PowerChalk was used to analyze the walking videos, which were taken in the sagittal plane.

Using the PowerChalk software and the pixel scale provided, the uploaded videos were advanced one frame at a time and the frame number of the first heel strike of the right foot, on the side closest to the camera, was identified. The Angle Measurement Tool was then used to measure the angle of the participant’s ankle by clicking the approximate locations of the lateral head of the fifth metatarsal, the lateral malleolus, and the lateral condyle of the femur, The angle of the knee was determined by clicking the approximate locations of the lateral malleolus, the lateral condyle of the femur, and the greater trochanter. Screenshots were taken of both angles. The video was then advanced one frame at a time until the second heel strike of this same right foot, completing one stride. The Angle Measurement Tool was again used to measure both the ankle and knee angles at each frame. Step and stride length were measured using a line measurement tool. Pixel measurements were converted into centimeters using the subject's height as a reference.

Angle measurements from each condition at the ankle and knee were recorded and plotted on graphs using Excel.