Normalized jerk: A measure to capture developmental characteristics of young girls' overarm throwing

Jin H. Yan, Richard N. Hinrichs, V. Gregory Payne, Jerry R. Thomas

    Research output: Contribution to journalArticlepeer-review

    20 Scopus citations

    Abstract

    This study was designed to examine the developmental differences in the speed and smoothness of arm movement during overarm throwing. The second purpose of this investigation was to evaluate whether jerk is a useful measure in understanding children's overarm throwing. Fifty-one girls, aged 3 to 6 years, voluntarily participated in the study. Each subject threw tennis balls as hard as she could toward a large target on the wall. A 2-camera video system was used to obtain 3-D coordinates of the hand and ball using the DLT algorithm. The variables of velocity and jerk (for the hand and ball) served as the movement outcome measures. The age-associated differences in velocity and normalized jerk (absolute jerk standardized relative to movement time and distance) were examined by ANOVAs. The results supported the hypothesis that the older subjects demonstrated faster and smoother hand movements than their younger counterparts during the forward acceleration phase (from the beginning of forward motion to ball release). In addition, the correlation results indicated that increased hand movement speed was associated with decreased movement jerk in older subjects, whereas increased hand speed was associated with increased jerk in younger subjects. The findings suggest that examining the jerk parameter (normalized or absolute jerk) is a useful and alternative approach to capture the variance of hand movement execution for children's overarm throwing.

    Original languageEnglish (US)
    Pages (from-to)196-203
    Number of pages8
    JournalJournal of Applied Biomechanics
    Volume16
    Issue number2
    DOIs
    StatePublished - Jan 1 2000

    Keywords

    • Age
    • Arm movement
    • Jerk
    • Young females

    ASJC Scopus subject areas

    • Biophysics
    • Orthopedics and Sports Medicine
    • Rehabilitation

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