Traditionally, post-exercise muscular alterations have been examined using invasive techniques that lack the ability to single out individual muscle groups. Sonomyography, tensiomyography, and electrical impedance myography allow for noninvasive skeletal muscle assessment. This project aimed to examine changes in muscle contractility and composition that occur in the early stages of recovery following unaccustomed exercise. METHODS: Twenty-one untrained adults (21.9 ± 1.9 y) performed exercise – 10 × 10 maximal eccentric knee extensions – with their nondominant leg. For each repetition, participants moved through 90° range of motion at 90°•s-1 with a passive return to the start position. Each set was separated by 60 seconds of rest. Sonomyography, tensiomyography, electrical impedance myography, and maximal isometric contractions of the knee extensors (RF & VL) of both legs were performed before (BL), immediately after (IP), and 24 hours post-exercise (24H). RESULTS: Peak torque and rate of torque development were unaltered in response to the eccentric protocol. Significant limb × time interactions were noted for reactance, phase angle, and delay time of the exercised VL, and echo intensity of the exercised RF. Compared to the dominant leg, the nondominant leg displayed significantly greater changes (p < 0.05) in VL delay time and RF echo intensity at IP. Following exercise, bilateral alterations were identified for reactance, phase angle, maximal displacement, delay time, contraction velocity, cross-sectional area, and thickness of the RF, as well as resistance, echo intensity, cross-sectional area, and thickness of the VL. No between-sex differences were noted in response to exercise. CONCLUSIONS: In the absence of performance decrements, sonomyography, tensiomyography, and electrical impedance myography successfully detected acute changes in skeletal muscle composition and function following an acute bout of eccentric exercise in untrained men and women. While the exercised leg exhibited specific responses in delay time and echo intensity, bilateral changes are theorized to have occurred due to contralateral stabilization of the non-exercised leg. The current results suggest that different muscle actions (i.e., eccentric and isometric) promote similar consequences to muscle strength, size, echogenicity, contractility, and bioelectrical properties.


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Graduation Date





Fukuda, David


Doctor of Philosophy (Ph.D.)


College of Community Innovation and Education


Learning Sciences and Educational Research

Degree Program

Education; Exercise Physiology









Release Date

May 2019

Length of Campus-only Access


Access Status

Doctoral Dissertation (Open Access)