Force Accuracy during Ramp Contractions of the Upper and Lower Extremity: The After-Peak Reduction
Doucet B.B., Mettler J.A., Griffin, L. and Spirduso, W.W. Force Accuracy during Ramp Contractions of the Upper and Lower Extremity: The After-Peak Reduction. Perceptual and Motor Skills 123: 244–257, 2016
Irregularities in force output are present throughout human movement and can impair task performance. We investigated the presence of a large force discontinuity (after-peak reduction, APR) that appeared immediately following peak in maximal effort ramp contractions performed with the thumb adductor and ankle dorsiflexor muscles in 25 young adult participants (76% males, 24% females; M age 24.4 years, SD ¼ 7.1). The after-peak reduction displayed similar parameters in both muscle groups with comparable drops in force during the after-peak reduction minima (thumb adductor: 27.5 7.5% maximal voluntary contraction; ankle dorsiflexor: 25.8 6.2% maximal voluntary contraction). A trend for the presence of fewer after-peak reductions with successive ramp trials was observed, suggesting a learning effect. Further investigation should explore underlying neural mechanisms contributing to the after-peak reduction.