Can pennation angles be predicted from EMGs for the primary ankle plantar and dorsiflexors during isometric contractions?

Abstract

Ultrasonography was used to measure pennation angle and electromyography (EMG) to record muscle activity of the human tibialis anterior (TA), lateral gastrocnemius (LG), medial gastrocnemius (MG), and soleus (SOL) muscles during graded isometric ankle plantar and dorsiflexion contractions done on a Biodex dynamometer. Data from eight male and eight female subjects were collected in increments of approximately 25% of maximum voluntary contraction (MVC) ranging from rest to MVC. A significant positive linear relationship (p < 0.05) between normalized EMG and pennation angle for all muscles was observed when subject specific pennation angles at rest and MVC were included in the analysis. These were included to account for gender differences and inter-subject variability in pennation angle. The coefficient of determination, R 2 , ranged between 0.76 for the TA to 0.87 for the SOL. The EMG-pennation angle relationships have ramifications for use in EMGdriven models of muscle force. The regression equations can be used to characterize fiber pennation angle more accurately and to determine how it changes with contraction intensity, thus providing improved estimates of muscle force when using musculoskeletal models.

Correlation between architectural variables and torque in the erector spinae muscle during maximal isometric contraction

“…Likewise, another study analysed the correlation between the other architectural variables used in the present study (pennation angle) and muscle activation of different leg muscles during maximal isometric contractions placing every muscle in their optimal fibre length setting. The values of the regression of each muscle were 0.76, 0.82, 0.82 and 0.87 for the tibialis anterior, lateral gastrocnemius, medial gastrocnemius and soleus, respectively (Manal, Roberts, & Buchanan, 2008). These results are not consistent with those observed in the present study, where none of the architectural variables showed a significant correlation with the functional variable used in this study (torque).…”

Human muscle fascicle behavior in agonist and antagonist isometric contractions

“…1,2,[5][6][7][8] Nevertheless, an implicit assumption of this method is that, during an isometric contraction, the relationship between the level of EMG activity and the mechanical output is the same when a muscle is acting either as an agonist or as an antagonist. 9,10 If this were the case, one would expect changes in EMG to be reflected by changes in architecture 11,12 that would be identical when the muscle is acting either as an agonist or as an antagonist.…”

Ultrasound Imaging and Analysis of Muscle Activity in Lower Limb

“…2-b shows a similar result, but the time difference between their peaks is smaller than Fig. 2-a. It has been shown that the maximum pennation angle is obtained during maximum EMG [5]. These measurements were taken from isometric contraction.…”