onthermal Ultrasound and Exercise in Skeletal Muscle egeneration

Objective: To determine whether continuous nonthermal herapeutic ultrasound (US) and low-intensity exercise (Ex) nfluence skeletal muscle regeneration after a standardized ontusion injury in an animal model. Design: Randomized controlled trial with blinded comparions in a 2 2 factorial (US by Ex) design. Setting: Animal care facility and exercise physiology biohemistry laboratory. Animals: Twenty male Wistar rats (age, 8mo) received a eproducible bilateral contusion injury to the gastrocnemius uscles. Ten gastrocnemius muscles from 5 noninjured, nonreated rats provided baseline control data. Interventions: US (continuous duty cycle, 3MHz; intensity, .1W/cm; transducer, 1cm; duration, 5min/d; duty cycle, 00%) and exercise (20min/d of low-intensity treadmill walkng at 14m/min). Gastrocnemius muscles from injured rats eceived exercise treatment alone (Ex NoUS), exercise and S treatment (Ex US), US treatment alone (NoEx US), and o treatment (NoEx NoUS). Main Outcome Measures: Ninety-six-hour postinjury musle mass, contractile protein concentration, fiber cross-sectional rea, number of nuclei per fiber, and myonuclear density. Results: Myonuclei per fiber were statistically greater in njured than in noninjured gastrocnemius muscle (P .05). here were no statistical differences (P .01) among the 4 njured treatment groups for any of the outcome measures hosen as biomarkers of skeletal muscle regeneration. Conclusions: There is no evidence that the specific continous US and Ex protocols investigated enhanced skeletal musle regeneration after contusion injury.