Effects of cryotherapy combined with therapeutic ultrasound on oxidative stress and tissue damage after musculoskeletal contusion in rats

Objective To investigate the combined effects of cryotherapy and pulsed ultrasound therapy (PUT) on oxidative stress parameters, tissue damage markers and systemic inflammation after musculoskeletal injury. Design Experimental animal study. Setting Research laboratory. Participants Seventy male Wistar rats were divided into five groups: control, lesion, cryotherapy, PUT, and cryotherapy + PUT. Interventions The gastrocnemius muscle was injured by mechanical crushing. Cryotherapy was applied immediately after injury (immersion in water at 10 degrees C for 20 minutes). PUT was commenced 24 hours after injury (1 MHz, 0.4 W/cm(2SPTA), 20% duty cycle, 5 minutes). All animals were treated every 8 hours for 3 days. Main outcome measures Oxidative stress in muscle was evaluated by concentration of reactive oxygen species (ROS), lipid peroxidation (LPO), anti-oxidant capacity against peroxyl radicals (ACAP) and catalase. Plasma levels of creatine kinase (CK), lactate dehydrogenase (LDH) and C-reactive protein (CRP) were assessed. Results When applied individually, cryotherapy and PUT reduced CK, LDH, CRP and LPO caused by muscle damage. Cryotherapy + PUT in combination maintained the previous results, caused a reduction in ROS [P = 0.005, mean difference 0.9 x 10(-8) relative area, 95% confidence interval (CI) 0.2 to 1.9], and increased ACAP {P = 0.007, mean difference 0.34 1/[relative area with/without 2,2-azobis(2-methylpropionamidine)dihydrochloride], 95% CI 0.07 to 0.61} and catalase (P = 0.002, mean difference 0.41 units/mg protein, 95% CI 0.09 to 0.73) compared with the lesion group. Conclusions Cryotherapy + PUT in combination reduced oxidative stress in muscle, contributing to a reduction in adjacent damage and tissue repair. 2016 Chartered Society of Physiotherapy. Published by Elsevier Ltd. All rights reserved.