<italic><bold>Context</bold>:</italic> This study aimed to examine the differences in electromyographic (EMG) activity of the biceps femoris long head (BFlh) and semitendinosus (ST) muscles, break-point angle (BPA), and the angle at peak BFlh EMG activity between bilateral and unilateral Nordic hamstring exercise (NHE) on a sloped platform. <italic><bold>Design</bold>:</italic> This study was designed as a case-control study. <italic><bold>Methods</bold>:</italic> Fourteen men participated in the study. The participants initially performed maximum voluntary isometric contraction (MVIC) on the prone leg curl to normalize the peak hamstring EMG amplitude as the %MVIC. Then, participants were randomized to perform the following 3 variations of NHE: bilateral (N40) or unilateral (N40U) NHE with a platform angle of 40°, and unilateral NHE with a platform angle of 50° (N50U). The EMG activities of the BFlh and ST and the knee flexion angle during the NHE variations were recorded to calculate the EMG activity of the BFlh and ST in terms of the %MVIC, the angle at peak BFlh EMG, and BPA. <italic><bold>Results</bold>:</italic> The BFlh %MVIC was significantly higher in N40U (<italic>P</italic> &lt; .05) and N50U (<italic>P</italic> &lt; .05) than in N40. A significant difference in BFlh %MVIC and ST %MVIC was observed between N40U (<italic>P</italic> &lt; .05) and N50U (<italic>P</italic> &lt; .05). The mean values of BPA and the angle at peak BFlh EMG were &lt;30° for all NHE variations. <italic><bold>Conclusions</bold>:</italic> In the late swing phase of high-speed running, BFlh showed higher EMG activity; thus, unilateral NHE may be a specific hamstring exercise for hamstring injury prevention.

The purpose of this study was to examine whether the NHE with an increased lower leg slope angle would enhance hamstring EMG activity in the final phase of the descend. The hamstring EMG activity was measured, the biceps femoris long head (BFlh) and the semitendinosus (ST). Fifteen male volunteers participated in this study. Subjects performed a prone leg curl with maximal voluntary isometric contraction to normalize the hamstring EMG activity. Subsequently, subjects performed the NHE, with the help of a certified strength and conditioning specialist, while the lower leg slope angle were randomly set at 0° (NH), 20° (N20), and 40° (N40). To compare hamstring EMG activity during the NHE variations, the knee flexion angle was set in the range from 0° to 50°, divided into five phases (0-10°, 10-20°, 20-30°, 30-40° and 40-50°), where 0° indicated that the knee was fully extended. To calculate the knee extension angular velocity, the knee flexion angle divided by time, and break point angle (BPA) was the angle at which 10°/s was exceeded. In the statistical analysis, a two-way repeated measures ANOVA was used for the hamstring EMG activity and a one-way repeated measures ANOVA was used for the BPA. The EMG activity of the BFlh and the ST in N20 and N40 was significantly higher than in NH at knee flexion angle of 0-20° (p < 0.05). For the BPA, NH (57.75° ± 13.28°), N20 (36.27° ± 9.89°) and N40 (16.26° ± 9.58°) were significantly higher in that order (p < 0.05). The results of this study revealed that the NHE with an increased lower leg slope angle shifted the BPA to the lower knee flexion angle and enhanced the hamstring EMG activity in the final phase of the descent.

This study aimed to investigate the in vivo kinematics of shear modulus of the lower leg muscles in patients with medial tibial stress syndrome (MTSS). The study population included 46 limbs with MTSS and 40 healthy limbs. The shear modulus of the medial head of the gastrocnemius, lateral head of the gastrocnemius, soleus, peroneus longus and tibialis anterior muscles were measured using shear wave ultrasound elastography. As a result, the shear modulus of the lower leg muscles was significantly greater in patients with MTSS than in healthy patients (p &lt; 0.01). Based on the differences in shear modulus of lower leg muscles between the patients with MTSS and healthy patients, the measurements obtained via shear wave ultrasound elastography could be used to evaluate risk factors of MTSS. (E-mail: kei.akiyama@jpnsport.go.jp) (C) 2016 World Federation for Ultrasound in Medicine & Biology.

Background: The rearfoot motion during sports activities in patients with the medial tibial stress syndrome (MTSS) is unknown. This study aimed to investigate the difference in kinematics of the rearfoot in MTSS patients (eight male soccer players) and control participants (eight male soccer players) during a forward step.
Methods: Sixteen male soccer players, including eight players with MTSS, participated. Forward step trials were recorded with cineradiographic images obtained at a sampling rate of 60 Hz. Geometric bone models of the tibia and talus/calcaneus were created from computed tomography scans of the distal part of one lower limb. Following a combination of approaches, anatomical coordinate systems were embedded in each bone model. The talocrural joint motion (relative motion of the talus with respect to the tibia) and subtalar joint motion (relative motion of the calcaneus with respect to the talus) were examined.
Results: A significantly larger range of internal/external rotation and inversion/eversion motion was observed in the subtalar joint of MTSS patients compared to healthy controls (P &lt; 0.05) from heel contact to heel off. There were no significant differences between the MTSS patients and healthy participants in the ranges of all talocrural joint angles during the forward step.
Conclusion: Our results indicate that the range of subtalar joint motion is greater in patients with MTSS during the stance phase of the forward step. The kinematic results obtained of this study may have important clinical implications and add quantitative data to an in vivo database of MTSS patients.

The purpose of this study was to compare angular change and translational motion from the medial longitudinal arch (MLA) and lateral longitudinal arch (LLA) during running between medial tibial stress syndrome (MTSS) and non-MTSS subjects. A total of 10 subjects volunteered, comprising 5 subjects with MTSS and 5 subjects without injury (non-MTSS) as the control group. All subjects performed the test movement that simulated running. Fluoroscopic imaging was used to investigate bone movement during landing in running. Sagittal motion was defined as the angular change and translational motion of the arch. A Mann-Whitney U-test was performed to determine the differences in the measured values between the MTSS and non-MTSS groups. The magnitude of angular change for the MLA and LLA was significantly greater for subjects with MTSS than for control subjects. Translational motion of the MLA and LLA of the MTSS group was also significantly greater than that of the non-MTSS group (all p &lt; 0.05). Soccer players with MTSS have an abnormal structural deformation of foot during support (or stance) phase of running, with a large decrease in both the MLA and LLA. This abnormal motion could be a risk factor for the development of MTSS in these subjects.

本研究は健常者を対象とし,ランニング動作時における距腿関節・距骨下関節のキネマティクスが,シューズ着用と裸足の条件間で異なるかについて明らかにすることを目的として実施した.若年健常者8名を対象とし,静止立位からのランニング動作を課し,踵部接地から踵部離地までの距腿関節および距骨下関節の動きを計測した.解析の結果,シューズ着用時に比べて裸足時に距骨下関節の外反および外旋,距腿関節の背屈の動きが大きい傾向にあった.本研究によってシューズ着用の有無により動きが異なることを明らかにすることができた.(著者抄録)