title: Estimating youth locomotion ground reaction forces using an accelerometer-based activity monitor.
abstract: To address a variety of questions pertaining to the interactions between physical activity, musculoskeletal loading and musculoskeletal health/injury/adaptation, simple methods are needed to quantify, outside a laboratory setting, the forces acting on the human body during daily activities. The purpose of this study was to develop a statistically based model to estimate peak vertical ground reaction force (pVGRF) during youth gait. 20 girls (10.9 ± 0.9 years) and 15 boys (12.5 ± 0.6 years) wore a Biotrainer AM over their right hip. Six walking and six running trials were completed after a standard warm-up. Average AM intensity (g) and pVGRF (N) during stance were determined. Repeated measures mixed effects regression models to estimate pVGRF from Biotrainer activity monitor acceleration in youth (girls 10-12, boys 12-14 years) while walking and running were developed. Log transformed pVGRF had a statistically significant relationship with activity monitor acceleration, centered mass, sex (girl), type of locomotion (run), and locomotion type-acceleration interaction controlling for subject as a random effect. A generalized regression model without subject specific random effects was also developed. The average absolute differences between the actual and predicted pVGRF were 5.2% (1.6% standard deviation) and 9% (4.2% standard deviation) using the mixed and generalized models, respectively. The results of this study support the use of estimating pVGRF from hip acceleration using a mixed model regression equation.
authors.affiliation: Biomedical Engineering Graduate Group, University of California Davis, Davis, California, United States of America.
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Neugebauer
authors.forename: David A
authors.initials: DA
authors.lastname: Hawkins
authors.forename: Laurel
authors.initials: L
authors.lastname: Beckett
mesh_terms: D000054:Acceleration; D000293:Adolescent; D002648:Child; D005260:Female; D006801:Humans; D008124:Locomotion; D008297:Male; D015233:Models, Statistical; D008991:Monitoring, Physiologic; D009068:Movement; D012044:Regression Analysis; D015203:Reproducibility of Results; D012420:Running; D016138:Walking