Power and precision grip force control in three-to-five-year-old children: velocity control precedes amplitude control in development

Abstract

The aim of this study was to examine the development of underlying motor control strategies in young children by characterizing the changes in performance of a visually guided force regulation task using two different grip formations; a whole-hand power grip (developmentally easier) and a thumb-index finger precision grip (developmentally more advanced). Typically developing preschool children (n=50, 3.0-5.5 years) used precision and power grips to perform a ramp and hold task with their dominant and non-dominant hands. Participants performed five trials with each hand and grip holding the force at 30% of their maximum volitional contraction for 3 s. The data were examined for both age-related and performance-related changes in motor performance. Across ages, children increased in strength, decreased in initial overshoot of the target force level, and decreased in rate of force release. Results of a cluster analysis suggest non-linear changes in the development of force control in preschool children, with a plateau in (or maturation of) velocity measures (rate of force increase and force decrease) earlier than in amplitude-related measures (initial force overshoot and force variability).

Does muscular weakness account for younger children's enhanced force variability?

“…This age-related difference in force variability is congruent with previous reports (Potter et al, 2006;Smits-Engelsman et al, 2003). Age-related reductions in force variability have been attributed to developmental constraints, including neurophysiological maturity, enhanced sensorimotor processing, muscular differentiation (Lazarus & Whitall, 1999), and experience driven improvements in adapting the motor output to task requirements (Deutsch & Newell, 2005;Halder et al, 2007;Smits-Engelsman, Westenberg et al).…”

“…As such, it is possible that previously reported increases in children's force variability (Deutsch & Newell, 2001) are not the result of developmental processes but rather a non-uniform normalization procedure that is biased against weaker (here younger) children. In line with this proposition is the recent report that stronger preschool children have better force control (Potter et al, 2006). The purpose of this investigation was to determine whether differences in force variability between children aged 6, 8, and 10 years and young adults are minimized or even eliminated if absolute muscular strength is taken into account.…”

“…This increase in strength is believed to be multifactoral, resulting from the interplay of such factors as increases in myelination (Fietzek et al, 2000), muscle hypertrophy (Lexell, Sjostrom, Nordlund, & Taylor, 1992), and improvements in muscle coordination (Lazarus & Whitall, 1999;Potter et al, 2006). Although the increase in muscular strength is concurrent with age-related developmental enhancements in motor Developmental Psychobiology.…”

“…It has been suggested that this age-related reduction in force variability results from developmental constraints, including neurophysiological maturity, increased muscular strength and enhanced sensorimotor processing, and experience driven improvements in adapting the structure of the motor output to task requirements (Deutsch & Newell, 2005;Potter, Kent, Lindstrom, & Lazarus, 2006;Smits-Engelsman, Westenberg et al).…”

Measurement Methods to Analyze Changes in Coordination During Motor Learning from a Non-linear Perspective

“…to show that movement patterning did not take a linear route but that the learners should sudden jumps during learning as well as regressions back to earlier movement pattern. Other applications of cluster analysis include basketball [97], handball [98], foot pressure data [99,100], swimming [101], grip force [102], finger force [103], body sway [104], and finger tremor [105], golf movement patterning [106].…”