Physiological insights into medial gastrocnemius function during eccentric contraction in normal and in acute atrophy – Quantification of 2D strain rate indices from Velocity Encoded Phase Contrast MR Imaging.
Usha Sinha1, Vadim Malis2, Robert Csapo3, and Shantanu Sinha3
1Physics, San Diego State University, San Diego, CA, United States, 2Physics, University of California at San Diego, San Diego, CA, United States, 3Radiology, University of California at San Diego, San Diego, CA, United States
In-vivo studies of muscle function under
different motion paradigms can elucidate the physiology of acute atrophy. This study maps the 2D strain rate tensor in
subjects performing eccentric contractions before and after Unilateral Limb Suspension
induced acute atrophy. As expected, strain
rate values are smaller during eccentric compared to isometric contractions, since
in the eccentric mode, muscle contraction occurs under lengthening conditions
resulting in a net smaller local elongation. Changes of SR indices with atrophy are negligible possibly due to a
balance of force loss from atrophy and greater force generation from a
potentially stiffer matrix.
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