Evaluation of Region and Extent of Muscle Damage after Marathon Running by Using Ultrasound Shear-Wave Elastograph

Abstract

Muscle damage induced by marathon running has been often evaluated by changes in maximal voluntary contraction torque or blood creatine kinase activity. However, these parameters cannot characterize the region and extent of muscle damage of individual muscles. It was recently reported that individual muscle stiffness assessed by ultrasound shear-wave elastography can quantify the extent of exercise-induced muscle damage. The present study aimed to evaluate the extent of marathon running-induced muscle damage of the lower limb, by using ultrasound shear-wave elastography. Twelve college recreational runners participated in the present study. Muscle stiffness were obtained from the vastus medialis, vastus lateralis, biceps femoris, semitendinosus, semimembranosus, and medial gastrocnemius, before and 1-3 days after the marathon running. Significant increase in muscle stiffness was observed only in the medial gastrocnemius after 1 and 2 days after marathon running. These results indicate that, in recreational runners, muscle damage induced by marathon running occurred in the plantar flexor, not in the quadriceps femoris and hamstring. Moreover, it is suggested that the muscle damage of the plantar