Korff, T., & Jensen, J. L. (2005). Effect of segmental growth on the force construction of pedaling as a function of speed. Medicine and Science in Sports and Exercise, 37(5), Supplement abstract 2051.

"Motor skill acquisition is characterized by improvements in the application of task-appropriate forces. Muscular and non-muscular forces act in concert to produce a resultant force that complies with the goal of the task. Non-muscular forces are directly dependent on the anthropometry of the performer. If the resultant force to be produced is the same between performers, inter-participant differences in anthropometry might require muscular adjustments to changing non-muscular forces. This effect might impinge on movement speed as it also influences non-muscular forces. Differences in the application of muscular forces may therefore represent functional adjustments needed to account for changes in anthropometry. Such adjustments could pose confounds if age-related differences in muscular forces are to be attributed to features of the neuromotor system" (p. S398-399).

This study investigated the effect of age-related changes in anthropometry on the application of muscular forces and how that effect depends on movement speed. An instrumentalized two-legged pedaling machine was developed. Forces to be produced were scaled in proportion to body mass while the kinematics were held constant across all simulations.

Relative changes in anthropometry between 5 and 10 years of age did not significantly influence muscular power at 60 or 120 rpm pedaling cadence. There were only small effect sizes due to age differences.

Implication. Since anthropometrical changes due to age did not influence muscular force application, force application can be attributed to the neuromotor system. With children aged 5 - 10 years, muscular force is primarily determined by technique which means coaches primarily should emphasize instruction in skill over most other factors associated with sport training.

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