Is the motor unit mean firing rate versus recruitment threshold relationship linear?

Advances in surface electromyographic (EMG) signal decomposition allow researchers to analyze data
for 20 –50 motor units per contraction. To simplify interpretation, some investigators rely on group
mean analysis of the mean firing rate versus recruitment threshold relationship, but it is unclear
if this association is linear. Objective : To determine whether this relationship is strongest when
analyzed via linear, quadratic, or cubic regression. Approach : Twenty-one men (mean   ±  SD
age   =  24  ±  4 years) and 16 women (21  ±  2 years) performed isometric contractions of the knee
extensors at 50% of maximal force while bipolar surface EMG signals were recorded from the vastus
lateralis. A decomposition algorithm was used to calculate the mean firing rate and recruitment
threshold of each motor unit at accuracy levels ranging from 90.0% –93.0%. Polynominal regression was
used to determine if each relationship was best fit with a linear, quadratic, or cubic model. We ...

Source: Physiological Measurement - September 28, 2019 Category: Physiology Authors: Kylie K Harmon, Ryan M Girts, Rob J MacLennan and Matt S Stock Source Type: research