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BackgroundMedial tibial stress syndrome (MTSS) is one of the most common causes of exercise-related leg pain in runners. Because stopping training due to pain from MTSS could decrease the athlete’s competitiveness, it is necessary to construct MTSS prevention and treatment programs. However, the effect of running, which is believed to cause MTSS, on shear elastic modulus of the posterior lower leg is unclear. Therefore, the purpose of this study was to investigate the effect of 30 min of running on shear elastic modulus of the posterior lower leg in healthy subjects.MethodsTwenty healthy males volunteered to participate in this study (age, 20.9 ± 0.6 y; height, 169.6 ± 4.5 cm; weight, 62.6 ± 5.2 kg). The shear elastic modulus of the posterior lower leg was measured using ultrasonic shear wave elastography before and immediately after a 30-min running task.ResultsShear elastic moduli of the flexor digitorum longus and tibialis posterior were significantly increased after 30 min running task. However, there were no significant changes in shear elastic moduli of the lateral gastrocnemius, medial gastrocnemius, peroneus longus and peroneus brevis.ConclusionThe results suggested that the increases in shear elastic moduli of flexor digitorum longus and tibialis posterior after running could be a risk factor for running-related MTSS development.

This study aimed to clarify the acute effect of static stretching (SS) with superficial cooling on dorsiflexion range of motion (DF ROM) and muscle stiffness. Sixteen healthy males participated in the cooling condition and a control condition in a random order. The DF ROM and the shear elastic modulus of medial gastrocnemius (MG) in the dominant leg were measured during passive dorsiflexion. All measurements were performed prior to (PRE) and immediately after 20 min of cooling or rested for 20 min (POST), followed by 2 min SS (POST SS). In cooling condition, DF ROM at POST and POST SS were significantly higher than that at PRE and DF ROM at POST SS was significantly higher than that at POST. In addition, the shear elastic modulus at POST was significantly higher than that at PRE and the shear elastic modulus at POST SS was significantly lower than those at PRE and POST. However, there were no significant differences in the percentage changes between PRE and POST SS between the cooling and control conditions. Our results showed that effects of SS with superficial cooling on increases in ROM and decrease in muscle stiffness were no more beneficial than those of SS alone.

It is well known that eccentric exercise induces muscle damage that is characterized by a prolonged decrease in muscle strength and range of motion, development of delayed onset muscle soreness, and swelling. Therefore, the present study aimed to compare the acute effects of hold-relax stretching (HRS) with those of static stretching (SS) on muscle strength and soreness. The participants comprised 28 male volunteers randomly assigned to either the HRS group (N = 14) or the SS group (N = 14). Initially, the participants of both groups performed 60 maximal eccentric contractions of the knee extensors. Two and four days after this exercise, each group performed either HRS or SS for 60 s at a time and repeated them six times for a total of 360 s. Muscle strength and soreness during stretching and contraction were measured before and immediately after HRS and SS. The results showed that the muscle soreness observed after eccentric contraction significantly decreased immediately after both HRS and SS were performed two and four days later. In addition, there were no significant changes in muscle strength immediately after both HRS and SS were performed two and four days later. The rate of change in muscle soreness after HRS was significantly higher than that after SS two days post eccentric contractions. These results suggest that while both HRS and SS can effectively decrease muscle soreness, the effect of HRS on muscle soreness was larger than the effect of SS.