Low Intensity Laser as an Adjuvant to Improve Muscle Strength after Exercise: A Case Report

Abstract

Muscle fatigue is a limiting factor in prosthetic patients and studies show that low intensity laser can improve performance and increase muscle strength. We tested a concentric exercise protocol comparing a test applied after 10 sessions without and with the use of laser using the Cybex Humac Norm® Test & Rehabilitation System in a patient with left lower limb amputation. First, a test was performed to determine the baseline value of peak torque, average power per repetition and total work performed. Ten exercise sessions and a new test were followed to determine the difference in power gain. Ten more sessions and a new test without laser application were performed to determine whether the torque increment level was reached, followed by ten more sessions with laser application 5 minutes before the exercise and a new test, with laser application, to evaluate the torque increment. An increase in PT was found of 5% for extensors and 7% for knee flexors in the second test in relation to baseline. The increase was 0% for the extensors and 11% for the flexors in the next test. After laser application there was an increase of 8% for the extensors and a deficit of 11% for the flexors. For TTR, the relative values for extenders and flexors were 3% and -3%, -10% and -2% (without laser) and 18% and 17% (with laser). We concluded that, in this protocol, the laser produced a gain in the peak torque of extensor muscles, but not of the flexors as well as a significant increase in the average power per repetition and the total work performed by both the extensors and the knee flexors, which may be of value as an adjuvant in the treatment of prosthetic patients.