Walking speed influences spatiotemporal but not symmetry measures of gait in children and adolescents with hemiplegia.

BACKGROUND: The measurement of gait is likely influenced by walking speed in children with hemiplegia, but this relationship is not well characterized. RESEARCH QUESTION: What is the influence of walking speed on spatiotemporal and symmetry measures of gait in children with hemiplegia, with consideration of side and footwear condition? METHODS: Children with hemiparetic gait due to stroke were recruited for a small pilot intervention study. Participants walked at self-selected and fast speeds while barefoot and while wearing shoes. Data from baseline sessions were included in this analysis. The influence of walking speed on five spatiotemporal gait measures was determined using a generalized estimating equation to calculate the proportion of variability in the gait measures that was explained by walking speed. Differences between sides and footwear conditions, and the relationships between walking speed and two symmetry measures, are also reported. RESULTS: A total of 820 steps were analyzed from ten children (11.2 ± 4.1 years). Walking velocity significantly influenced all spatiotemporal measures of gait. As speed increased, step length increased and all temporal measures decreased, on both paretic and nonparetic sides. Wearing shoes increased step length and stance time for both paretic and nonparetic sides, and slowed step time on the nonparetic side. Regardless of footwear, the paretic side demonstrated slower step and swing times, and faster stance and single support times. We did not observe significant relationships between walking speed and gait symmetry. SIGNIFICANCE: Our observations suggest that walking speed alone influences the spatiotemporal measurement of gait in children with hemiplegia and should be considered in the interpretation of walking function. Yet, controlling for walking speed is often not feasible or not preferred in this population. We offer suggestions for clinicians and researchers who seek to measure gait during overground walking at freely-selected speeds.

Normalizing step-to-step variability to age in children and adolescents with hemiplegia.

BACKGROUND: Children with hemiplegia often demonstrate gait deviations including increased variability and asymmetry. Step-to-step gait variability decreases over childhood and increases in the presence of neurologic dysfunction. Gait variability in children with hemiplegia should therefore be interpreted in reference to age-related norms RESEARCH QUESTION: Does conversion of the enhanced gait variability index (eGVI) to age-normalized z-scores improve interpretation of gait variability in children with hemiplegia? METHODS: Ten children (11.2 +/- 4.1 years) with hemiparetic gait due to stroke were recruited for a small prospective pilot intervention study. Participants walked at self-selected speed over an instrumented walkway while barefeet and while wearing shoes. eGVI values from baseline sessions were calculated and converted to age-normalized z-scores (eGVIz) based on published norms. Differences in gait variability between sides and footwear conditions, and its relationship to walking speed, were examined. RESULTS: There were no differences in raw eGVI or eGVIz between paretic and nonparetic sides (eGVI p = 0.31; eGVIz p = 0.31) or between footwear conditions (eGVI p = 0.62; eGVIz p = 0.33). Average raw eGVI values were just over two standards deviations above the reference mean of 100 (121.2, 122.1, 120.3 for mean (average of both limbs), nonparetic side and paretic side, respectively), indicating significantly greater step-to-step gait variability than in typical gait. However, when converted to age-normalized z-scores (eGVIz), variability deviated less from the normative sample, averaging just over one standard deviation above the reference mean (1.2, 1.3, 1.1 for mean, nonparetic side and paretic side, respectively). We also observed a relationship between eGVIz and walking speed in our sample. SIGNIFICANCE: We suggest that eGVI values in children be converted to z-scores or otherwise age-normalized so as not to inflate the degree of variability reported in clinical pediatric populations. Future work with larger samples will offer greater insight into gait variability in various clinical pediatric populations.