Marathon-induced Muscle Stiffness Dynamics

The first muscle stiffness sample was collected on the day before the marathon. The quadriceps muscle of the thigh and the triceps muscle of the calf were measured. All measurements were performed in a designated room. Rigidity measurements were taken at rest the day before the marathon. Subsequent measurements were made 1–2 h before the start and just after the end of the marathon run. All tests were performed by the same trained person to operate the MYOTON device.
The participants were prone on their backs or their stomachs on a unique bed, and they rested for 10 min before muscle stiffness measurements were taken. Testing sites on each muscle were located using a tape measure and marked using a skin-safe pen (Figure 1). A pillow was placed under the head, and a unique roller pillow was placed under the lower leg to aid relaxation. One series of three single Myoton measurements of each muscle group (12 points) were measured separately for the left and right legs. In addition, for a better understanding of the problem, the functionality of the lower limb was also determined - the dominant and non-dominant leg. The dominant leg for a particular runner was determined based on the information provided by the marathoner in the questionnaire.
The reliability between trials (within session) of the one selected muscles (two series of 10 single measurements) of each group was tested using intraclass correlation coefficient (ICC) model. Domholdt (1993) classification scales for interpreting ICCs was used: very high =1.00–0.90; high = 0.89–0.70; moderate = 0.69–0.50; low = 0.49–0.26. This indicated that Rectus femoris reach (ICC = 0.82) and Gastrocnemius (ICC = 0.85). The high reliability coefficient indicated that applied tests represent consistent measurement of muscle stiffness data among the runners.