Overground, conventional treadmill, and aquatic treadmill walking joint kinematics differ in typically developing children and adolescents.

Gait training is a common rehabilitation tool using repeated gait cycles to promote motor learning and improve overall walking ability (Booth et al., 2018; Kim & Lee, 2016;Novy et al., 2013). The purpose of this study was to quantify differences in peak and time-to-peak ankle plantarflexion, knee flexion, and hip flexion in typically developing children (7 males, 8 females, age 11.3 ± 4.1 years, 1.46 ± 0.18 m, and 44.2 ± 16.8 kg) during overground, conventional treadmill, and aquatic treadmill walking at three walking speeds (slow, normal, and fast). We hypothesized that increasing walking speeds and different walking environments would affect peak and time-to-peak kinematics of the lower limb. Faster speeds significantly increased peak kinematics, with peak plantarflexion increasing from 19.6⁰ during the slow speed condition to 25.7⁰ during the fast speed condition (p < 0.01). The overground environment had the highest peak knee flexion (67.4⁰), a 24.7⁰ increase compared to conventional treadmill and a 34.2⁰ increase compared to the aquatic treadmill (p < 0.01). Time-to-peak kinematics for peak ankle plantarflexion occurred 7.8 % and 9.9 % earlier in the gait cycle when compared to overground (p < 0.01) and conventional treadmill (p < 0.01). Faster speeds also resulted in earlier time-to-peak kinematics compared to slow speeds for ankle plantarflexion (p < 0.01) and hip flexion (p < 0.01). Findings of this study suggest that walking speed and environment significantly influence lower limb kinematics in typically developing children. Therefore, researchers should consider environmental factors when designing and evaluating gait training interventions.