Radial pressure wave treatment accelerates recovery from immobilization-induced soleus muscle atrophy and improves ankle range of motion in mice.

PURPOSE: Disuse muscle atrophy following immobilization is characterized by decreased muscle mass and reduced joint range of motion (ROM). Radial pressure wave (RPW) treatment is a non-invasive modality that delivers mechanical energy to musculoskeletal tissues, but its efficacy in skeletal muscle recovery from disuse atrophy remains largely unknown. We examined whether RPW treatment accelerates soleus muscle structural recovery and passive ankle dorsiflexion ROM following immobilization-induced atrophy in mice. Furthermore, we investigated the underlying molecular signaling cascades and gene expression profiles associated with RPW-mediated recovery.

METHODS

Male C57BL/6 J mice ([Formula: see text] per group) underwent 14 days of unilateral hindlimb immobilization, followed by a 7-day recovery period with or without RPW treatment (1 bar, 10 Hz, 2,000 pulses, three sessions on alternate days). Soleus muscle mass, fiber cross-sectional area (CSA), and passive ankle dorsiflexion ROM were assessed. Candidate genes identified as differentially expressed by exploratory RNA-sequencing in one mouse per group ([Formula: see text]) were subsequently evaluated by quantitative PCR and immunoblotting across all animals in the full cohort ([Formula: see text] per group).

RESULTS

RPW treatment increased fiber CSA to [Formula: see text] (vs. [Formula: see text] in the sham group) and improved ankle dorsiflexion ROM to [Formula: see text] (vs. [Formula: see text]). Gene set enrichment analysis revealed suppression of the forkhead box O (FoxO) signaling pathway and enrichment of the extracellular matrix (ECM) remodeling pathway. Igf1 expression was higher in the RPW group ([Formula: see text]-fold vs. sham: [Formula: see text]-fold), accompanied by elevated Akt phosphorylation. Col3a1 was uniquely upregulated in the RPW group ([Formula: see text]-fold vs. [Formula: see text]-fold).

CONCLUSION

RPW treatment accelerates the recovery of soleus muscle structure and improves passive ankle dorsiflexion ROM following immobilization-induced atrophy in mice.