D. Results

For the two natural gait speed conditions, the subject walked at an average speed of 1.11 m/s and 1.29 m/s, for the unaffected and affected leg, respectively. When instructed to increase gait speed, the subject walked at an average speed of 1.59 m/s and 1.65 m/s, respectively. As gait speed increased, average stride length increased for both legs, with the affected leg producing a longer average stride length at both speeds. At speeds of 1.11 m/s and 1.29 m/s, the unaffected leg had a stride length of 1.26 m and the affected leg had a stride length of 1.40 m, a difference of 11.7%. At speeds of 1.59 m/s and 1.65 m/s, the unaffected leg had a stride length of 1.50 m and the affected leg had a stride length of 1.60 m, a difference of 6.30% (Table 1). At the natural gait speed, the subject spent 17.6% of the gait cycle in midstance on the unaffected leg and 16.4% of the gait cycle in midstance on the affected leg, on average. At the increased gait speed, the subject spent 13.0% of the gait cycle in midstance on the unaffected leg and 11.5% of the gait cycle in midstance on the affected leg, on average (Table 2). As gait speed increased, the percent of the gait cycle spent in midstance decreased for both legs. At the natural gait speed, the amount of time the unaffected leg spent in midstance was greater by 6.82%, while at the increased gait speed, the amount of time the unaffected leg spent in midstance was greater by 14.4%.

Table 1. Average stride length and average speed for each condition during one complete gait cycle. Stride length increased with increasing gait speed, with the affected leg producing a longer stride length at both speeds.

Table 2. Average percent of the gait cycle spent in midstance for each condition. Percent of gait spent in midstance decreased with increasing speed and was lower in the affected leg at both speeds.

At the natural speed, the unaffected leg exhibited a greater degree of hip extension during stance compared to the affected leg but exhibited similar degrees of extension during swing. At the increased speed, the hip joint angles were similar, except during swing phase where the affected leg produced a greater degree of hip extension (Figure 3). For the knee joint, the differences between the unaffected and affected legs during all four conditions were negligible. However, during the midswing phase, the knee joint of the affected leg at the increased speed was more extended, exhibiting a joint angle that was 13.1° greater than that examined in all other conditions during this phase of gait (Figure 4). Differences in the ankle joint angle between conditions were also negligible with the exception of the affected leg at natural gait speed where the ankle exhibited a greater degree of plantarflexion from early- to mid-stance and during swing (Figure 5).

Figure 3. Angle of the hip joint during the gait cycle. The unaffected leg exhibited a greater degree of hip extension during stance at the natural speed compared to the other three conditions.

Figure 4. Angle of the knee joint during the gait cycle. The affected leg exhibited a greater degree of knee extension during midswing at the increased gait speed compared to the other three conditions.

Figure 5. Angle of the ankle joint during the gait cycle. The affected leg exhibited a greater degree of plantarflexion during early- to mid-stance and swing at the natural gait speed compared to the other three conditions.