Exercise Science (B.S.)

Document Type and Release Option

Thesis (open access)

Faculty Mentor

Daniel Czech


A pennate muscle has fascicles that attach obliquely to its tendon. In parallel, more fascicles can be aligned allowing for greater production of force. In previous research, pennation angle has been measured using ultrasound while in a laying supine position. The purpose of this study was to measure pennation angle of the gastrocnemius muscle with ultrasound while standing neutral, in a mechanically loaded position. 16 participants, one two separate days, had their ultrasound imaging taken in three different foot orientations: neutral, fifteen degree adduction / abduction positions. This information was then be analyzed using ImageJ software. This research shows the measurements of the gastrocnemius muscle pennation angle during standing are reliable, and can be used to study the effect of pennation angle on force production. As hypothesized, pennation angle measurements were reliable over a two day period while standing in an upright position. For laying in the prone position, the mean and standard deviations from the reliability of pennation angles were 9.4 ± 0.9 laterally and 12.6 ± 0.7 medially. For standing in the neutral position, the mean and standard deviation from the reliability of pennation angles were 9.5 ± 0.9 laterally and 12.3 ± 0.8 medially.