Electrically Stimulated Eccentric Contraction Training Enhances Muscle Mass, Function, And Size Following Volumetric Muscle Loss.

Volumetric muscle loss (VML) overwhelms muscle's innate capacity for repair and can lead to permanent disability. The standard of care for VML injuries includes physical therapy, which can improve muscle function. The objective of this study was to develop and evaluate a rehabilitative therapy using electrically stimulated eccentric contraction training (EST) and determine the structural, biomolecular, and functional response of the VML injured muscle. This study implemented EST using three different frequencies (50, 100, and 150 Hz) in VML injured rats starting at 2 weeks post-injury. Four weeks of EST at 150 Hz showed a progressive increase in eccentric torque with an improvement in muscle mass (~39 %), myofiber cross-sectional area (CSA), and peak isometric torque (~37.5 %) relative to the untrained VML injured sham group. EST at 150 Hz group also increased the number of large type 2B fibers (>5000 µm 2 ). Elevated gene expression of markers associated with angiogenesis, myogenesis, neurogenesis, and an anti-inflammatory response was also observed. These results suggest that VML injured muscles can respond and adapt to eccentric loading. The results of this study may aid in developing physical therapy regimens for traumatized muscles. This article is protected by copyright. All rights reserved.