Low intensity, high frequency vibration training to improve musculoskeletal function in a mouse model of volumetric muscle loss

Abstract

This study's objective was to investigate the extent to which two different levels of low‐intensity vibration training (0.6 g or 1.0 g) affected musculoskeletal structure and function after a volumetric muscle loss (VML) injury in male C57BL/6J mice. All mice received a unilateral VML injury to the posterior plantar flexors. Mice were randomized into a control group (no vibration; VML‐noTX), or one of two experimental groups. The two experimental groups received vibration training for 15‐min/day, 5‐days/week for 8 weeks at either 0.6 g (VML‐0.6 g) or 1.0 g (VML‐1.0 g) beginning 3‐days after induction of VML. Muscles were analyzed for contractile and metabolic adaptations. Tibial bone mechanical properties and geometric structure were assessed by a three‐point bending test and microcomputed tomography (µCT). Body mass‐normalized peak isometric‐torque was 18% less in VML‐0.6 g mice compared with VML‐noTx mice (p = 0.030). There were no statistically significant differences of vibration intervention on contractile power or muscle oxygen consumption (p ≥ 0.191). Bone ultimate load, but not stiffness, was ~16% greater in tibias of VML‐1.0 g mice compared with those from VML‐noTx mice (p = 0.048). Cortical bone volume was ~12% greater in tibias of both vibration groups compared with VML‐noTx mice (p = 0.003). Importantly, cross‐section moment of inertia, the primary determinant of bone ultimate load, was 44% larger in tibias of VML‐0.6 g mice compared with VML‐noTx mice (p = 0.006). These changes indicate that following VML, bones are more responsive to the selected vibration training parameters than muscle. Vibration training represents a possible adjuvant intervention to address bone deficits following VML.