Effectiveness of low-dose pulsed ultrasound for treatment of delayed-onset muscle soreness: A double-blind randomized controlled trial

Purpose: To evaluate the effectiveness of low dose pulsed ultrasound for the treatment of delayed-onset muscle soreness (DOMS).

Methods: Ninety female university students participated in a double-blind, placebo-controlled, randomized trial. The subjects were randomly assigned into three equal groups. DOMS was induced in the non-dominant elbow flexors of all subjects with voluntary eccentric contractions on a dynamometer. Group 1 was treated with pulsed ultrasound (spatial average-temporal peak intensity: 0.8 W/cm $^{2}$ , spatial average-temporal average: 0.16 W/cm $^{2}$ , pulse ratio 1:4 for 10 minutes over 5 consecutive days). Group 2 received sham pulsed ultrasound and the control group received no treatment. The results of therapy were assessed by evaluating perceived muscle soreness, elbow flexor muscle strength, range of motion, and creatine kinase activity.

Results: A Friedman's repeated-measures test for muscle soreness results demonstrated a significant change in the mean of perceived muscle soreness in all groups. The first significant decrease in muscle soreness occurred 144 hours after exercise in the experimental and control groups and 120 hours after the exercise in the placebo group. At the end of treatment, there were no significant differences in muscle soreness among the 3 study groups.

Conclusion: Low dose pulsed ultrasound therapy did not significantly reduce the effects of DOMS on soreness perception, active-elbow flexion angle, or muscle strength.