317 Motor Control, 2012, 16, 317-328 © 2012 Human Kinetics, Inc. Masci, Vannozzi and Cappozzo are with the Dept. of Human Movement and Sport Sciences, University of Rome “Foro Italico”, Rome, Italy. Getchell is with the Dept. of Kinesiology and Applied Physiology, University of Delaware, Newark, DE. Assessing Hopping Developmental Level in Childhood Using Wearable Inertial Sensor Devices Ilaria Masci, Giuseppe Vannozzi, Nancy Getchell, and Aurelio Cappozzo Assessing movement skills is a fundamental issue in motor development. Current process-oriented assessments, such as developmental sequences, are based on sub- jective judgments; if paired with quantitative assessments, a better understanding of movement performance and developmental change could be obtained. Our purpose was to examine the use of inertial sensors to evaluate developmental dif- ferences in hopping over distance. Forty children executed the task wearing the inertial sensor and relevant time durations and 3D accelerations were obtained. Subjects were also categorized in diferent developmental levels according to the hopping developmental sequence. Results indicated that some time and kinematic parameters changed with some developmental levels, possibly as a function of anthropometry and previous motor experience. We concluded that, since inertial sensors were suitable in describing hopping performance and sensitive to develop- mental changes, this technology is promising as an in-ield and user-independent motor development assessment tool. Keywords: hopping, inertial sensor, children, motor development, biomechanics During childhood, the acquisition of motor skills is crucial not only for the development of speciic motor behaviors, but also for cognitive, afective and social personality development (Payne & Isaacs, 2008; helen, 1995). Researchers have suggested that the acquisition of fundamental movement skills (FMS), such as run- ning, throwing or jumping, may positively correlate with physical activity levels, health-related itness and self-esteem (Stodden, Langendorfer, & Roberton, 2009; Stodden & Goodway, 2007). In other words, as motor skill proiciency improves, children may become more active and it (Stodden et al., 2008), laying the founda- tion for a more physically active adulthood (Clark & Metcalfe, 2002; Tammelin, Naya, Hills, & Jarvelin, 2003). his suggests that knowledge of individuals’ motor development is critical to understand their overall development.