Background: The Nordic hamstring exercise is a closed-chain exercise that effectively activates all lower extremity muscles, but there is a lack of consideration of ankle joint which affects exercise effectiveness. One of the major advantages of the Nordic exercise have been known as strengthening lower extremity extensors. This manifests the exercise increases activities of the ankle plantar flexors as well as hip extensors. Objectives: To investigated the impacts of changes in ankle position on the lower extremity musculature and subjective difficulties during the Nordic hip extension exercise. Design: Cross-sectional study. Methods: Twenty the healthy male participants participated in this study. Participants perform three variations of the Nordic exercises including three ankle positions. Each Nordic exercise was defined as ankle position (neutral, dorsiflexion and plantar flexion). During the Nordic exercise, erector spine (ES), gluteus maximus (GM), biceps femoris (BF), gastrocnemius (GCM) activities and subjective difficulties (Borg RPE score) were measured. Results: Muscular activities of the biceps femoris and gastrocnemius were significantly different among the three ankle conditions, which showed controversial results (P<.05). The biceps femoris activity was significantly higher with the dorsiflexion condition, compared to the others (P<.05). On the other hand, activity of the gastrocnemius was significantly higher with the plantarflexion position compared to the others (P<.05). Conclusion: Present study suggests the ankle positional changes could affect lower muscular activities during the Nordic exercise. Although it is difficult to affirm the causes due to limited data, selective activation of the biceps femoris might accomplish with ankle dorsi flexion and that of the gastrocnemius might accomplish with the ankle plantarflexion during the Nordic exercises.

Background: The gluteus maximus (GM) muscle comprise the lumbo-pelvic complex and is an important stabilizing muscle during leg extension. In patients with low back pain (LBP) with weakness of the GM, spine leads to compensatory muscle activities such as instantaneous increase of the erector spinae (ES) muscle activity. Four-point kneeling arm and leg lift (FKALL) is most common types of lumbopelvic and GM muscles strengthening exercise. We assumed that altered hip position during FKALL may increase thoraco-lumbar stabilizer like GM activity more effectively method. Objects: The purpose of this study was investigated that effects of the three exercise postures on the right-sided GM, internal oblique (IO), external oblique (EO), and multifidus (MF) muscle activities and pelvic kinematic during FKALL. Methods: Twenty eight healthy individuals participated in this study. The exercises were performed three conditions of FKALL (pure FKALL, FKALL with 120° hip flexion of the supporting leg, FKALL with 30° hip abduction of the lifted leg). Participants performed FKALL exercises three times each condition, and motion sensor used to measure pelvic tilt and rotation angle. Results: This study demonstrated that no significant change in pelvic angle during hip movement in the FKALL (p > 0.05). However, the MF and GM muscle activities in FKALL with hip flexion and hip abduction is greater than pure FKALL position (p < 0.001). Conclusion: Our finding suggests that change the posture of the hip joint to facilitate GM muscle activation during trunk stabilization exercises such as the FKALL.

이 연구의 목적은 6주간의 엉덩관절 강화 훈련이 근력, 동적 자세 조절 및 하체 손상 준거에 미치는 영향을 보고자 하였다. 운동선수 20명을 운동군과 통제군으로 분류하여, 운동군은 주 3회, 60분, 6주간 엉덩관절 강화훈련을 하였다. 이 연구의 측정 변인은 유연성, 근력, 동적 자세 조절 및 하체 부상 준거로 하였다. 연구 결과 유연성에서 운동의 효과가 유의하지 않았으나 배근력에서는 유의하였다. 동적 자세 조절 결과, 좌·우 후방 가쪽 및 안쪽에서 운동의 효과가 유의하였다. 또한 종합점수에서도 운동의 효과가 유의하였고, 좌·우 다리 간의 차이는 없었다. 결론적으로 엉덩관절 강화 운동은 근력과 동적 자세 조절 능력의 증가와 하체 손상의 우려는 감소시키는 것으로 나타났다.

This study investigated the effect of a load of 15% body weight on trunk, pelvis and hip joint coordination and angle variability in subjects with and without chronic low back pain (CLBP) during an anterior load carriage task. Thirty volunteers participated in the study (15 without CLBP, 15 with CLBP). All participants were asked to perform an anterior carriage task with a load of 15% body weight. The outcome measures included the means and standard deviations for measurements of three-dimensional coordination and angle variability of the trunk, pelvis and hip joint. As CLBP patient group .06, control group .70, the correlation coefficient between the groups showed a significant difference only in trunk-pelvic in the sagittal plane (p<.05). Angle variability of CLBP patient group increased significantly in the trunk in frontal plane, the pelvis in all sagittal plane, frontal plane, transverse plane, and the hip in sagittal plane, the hip in frontal plane than angle variability of control group (p<.05). This results mean that the CLBP patient group showed a disconnected coordination pattern in the trunk-pelvis in the sagittal plane, an increased pelvic angle variability in all three planes, and hip angle variability in the sagittal, and frontal planes. The CLBP patient group may have developed a compensatory movement of the pelvis and hip joint arising from the changed stability due to the abnormal coordination patterns of the trunk-pelvic in the sagittal plane. Therefore, CLBP symptoms can potentially worsen in the pelvis and adjacent hip joint in CLBP patients who perform weight-related behaviors in their daily lives. Further research is needed to determine the three-dimensional characteristics of the electromyography and neuromuscular aspects of subjects with CLBP.

Excessive lumbar flexion during sit-to-stand (STS) is a risk factor for lower back pain. Postural taping can prevent unwanted flexion of the lumbar spine. This study aimed to demonstrate the effect of taping the lower back on the lumbopelvic region and hip joint kinematics during STS. Sixteen healthy subjects participated. All subjects performed the STS with and without taping of the lower back. A three-dimensional motion analysis system was used to measure the kinematics of the lumbar spine, pelvis, and hip joint during STS. The angle of the peak lumbar flexion, pelvic anterior tilting, and hip flexion and angular displacement of the lumbar spine between starting position and maximal lumbar flexion were collected. Paired t-tests, or Wilcoxon's rank-sum test for non-parametric distribution, were used to assess differences in the measurements with and without taping. A p-value ＜.05 was taken to indicate a significant difference. Significant differences were observed in the angle of the peak lumbar flexion, pelvic anterior tilting, hip flexion and angular displacement of the lumbar spine (p＜.05). Taping was associated with a significant decrease in the angle of peak lumbar flexion and angular displacement of the lumbar spine between the starting position and maximal lumbar spine flexion. In addition, the peak angle of pelvic anterior tilting and hip flexion were significantly increased with taping. The findings of this study suggest that taping the lower back can decrease excessive lumbar flexion, and increase the pelvic anterior tilting and hip flexion motion during STS.

The purpose of this study was to examine the effects of hip joint mobilization (HJM) on walking ability, balance ability, and the joint range of motion in stroke patients to minimize the problems of the musculoskeletal system in patients with central nervous system diseases. All volunteers were randomly assigned to the HJM group (n1=14) and the general neurodevelopment therapy (NDT) group (n2=16). The HJM procedure involved applying Maitland mobilization techniques (distraction, lateral gliding, inferior gliding, and anterior gliding) by grade 3 to both hip joint. The mobilization process included mobilization and NDT for 15 min/day, 3 days a week for 4 weeks. The outcome measures were evaluated, including the hip joint passive range of motion (ROM) test and femur head anterior glide test (FHAG) using prone figure four test, dynamic and static balance abilities [timed up and go (TUG) test and center of pressure (COP) analysis], and walking ability [10-meter walking test (10MWT) and 6-min walking test (6MWT)]. Both the groups showed significant post-training differences in the hip joint ROM (FHAG and degree of hip extension) and 10MWT. The post-training improvements in the TUG test were significantly greater in patients of the HJM group than in the NDT group; however, there were no post-training improvements in COP in both groups. Patients in the HJM group showed post-training improvement in the 6MWT; however, statistically significant differences were not observed. Patients in the NDT group showed post-training improvements in the 6MWT. These results suggest that HJM improves hip joint ROM, dynamic balance ability, and walking speed in stroke patients. However, further studies are required to evaluate the long-term therapeutic efficacy of HJM in stroke patients.

The purpose of this study is to decrease a stress shielding effect shown in the hip joint. To conduct this study, the clad materials were produced by using an explosion welding method with two materials that were different in the elastic modulus like Ti-6Al-4V alloy and pure Ti. As for the clad materials, the Ti-6Al-4V alloy with large elastic modulus was designed as the neck of femur, and the pure Ti with small elastic modulus as the body of femur. The joints of clad materials formed by the explosion welding showed the typical wave shape, and its thickness was about 0.2㎛. New crystal or grain structure was not formed in the joints. In addition, the Vickers hardness in the joints formed the middle value between the base metal and clad metal. As a result of manufacturing prototype by processing the clad materials in three dimensions, this study gained good shape, and if it is to be applied to clinical in the future, this researcher can expect good results. From the result of this research above, it may be summed up as follows. It is considered as the stress shielding phenomenon showed on the hip joint can be decreased to a certain degree if this researcher is to utilize two clad materials with different elastic modulus like Ti-6Al-4V alloy and pure Ti

In this study, a large modulus of elasticity of the titanium alloy in use, to create artificial hip stress shielding effect appears to reduce the head portion is excellent in the strength of Ti-6Al-4V, making bone pusher which requires low elastic modulus relative modulus of pure titanium grade 2, using a small two metal after welding by explosion welding hip was made. Explosion pressure welding by the welding region with respect to the mechanical properties and the tissue was observed.

This study investigated the effects of axillary crutch length on trunk muscle activity and lumbo-pelvic-hip complex movements during crutch gait. Eleven healthy men participated in this study. The participants performed a three-point gait with optimal, shorter, and longer crutch lengths. Weight-bearing (WB) side was determined as the dominant leg side. The electromyography (EMG) activity of the bilateral rectus abdominis (RA) and erector spinae (ES) muscles and lumbo-pelvic-hip complex movements were monitored using a three-dimensional motion system with wireless surface EMG. Differences in the EMG activity of RA and ES muscles and range of motion (ROM) of lumbar spine, pelvis, and hip among conditions were analyzed using one-way repeated-measures analysis of variance, and a Bonferroni correction was conducted. There was less RA muscle activity on the WB side under the optimal crutch length condition compared with shorter and longer crutch length conditions (p<.05). The EMG activity of the RA muscle on the non-WB side and ES muscle on the WB side were significantly decreased under the optimal crutch length condition compared with shorter crutch length condition (p<.05). No significant differences in the EMG activity of the ES muscle on the non-WB side and ROM of lumbo-pelvic-hip complex were found among conditions (p>.05). These findings indicate that the optimal crutch length improves the trunk muscle efficiency during crutch gait.

The pelvic compression belt (PCB) contributes to improving sacroiliac joint stability, and it has been used as an additional therapeutic option for patients with sacroiliac joint pain (SIJP). This study aimed to investigate whether the muscle activation patterns of the supporting leg was different between asymptomatic subjects and subjects with SIJP during one-leg standing, and how it changes with the PCB. 15 subjects with SIJP and 10 asymptomatic subjects volunteered to participate in this study. Surface electromyography (EMG) data (reaction time [RT] and muscle activation) were collected from the internal oblique, lumbar multifidius, gluteus maximus and biceps femoris muscles during one-leg standing with and without the PCB. Without the PCB condition, in the SIJP group, the biceps femoris muscle showed the fastest RT among all muscles (p<.05), whereas in the asymptomatic group, the RT of the internal oblique muscle was the most rapid (p<.05). In condition without the PCB, the biceps femoris EMG amplitudes in the SIJP group were significantly greater than that in the asymptomatic group (p<.05). After the application of the PCB, the RT of the biceps femoris muscle was significantly increased only in the SIJP group (p<.05). Moreover, the biceps femoris EMG amplitudes significantly decreased and the gluteus maximus EMG amplitudes significant increased only in the SIJP group by applying the PCB (p<.05). However, this had no such effect on the gluteus maximus and biceps femoris EMG patterns in the asymptomatic group (p>.05). Thus, this study supports the applying the PCB to patients with SIJP can be used as a helpful option to modify the activation patterns of the gluteus maximus and biceps femoris muscle.

Although there have been various studies related to the body's movement from a sitting to a standing position (sit-to-stand task), there is limited information on the kinematic changes on the frontal and transverse planes. The purpose of this study was to ascertain how pelvic tilt affects kinematic changes in the frontal and transverse planes in the hip and knee joints during a sit-to-stand task. For this study, 33 healthy participants (13 female) were recruited. Each participant rose from a sitting to a standing posture at his or her preferred speed for each of three different pelvic tilt trials (anterior, posterior, and neutral), and the measured angles were analyzed using a 3-D motion analysis system. A one-way repeated measure analysis of variance was performed with Bonferroni's post hoc test. In addition, an independent t-test was carried out to determine the sex differences in hip and knee joint kinematic changes during the sit-to-stand tasks. The results were as follows: 1) The hip and knee joint angle in the frontal and transverse planes showed a significant difference between the different pelvic tilt postures during sitting in the pre-buttock lift-off phase (pre-LO) (p<.05). Compared to the posterior pelvic tilt posture, the anterior pelvic tilt posture involved significantly greater hip joint adduction and internal rotation, knee joint adduction, and reduced internal rotation of the knee joint. 2) Sex differences were found with significant differences for males in the initial and maximal angles in the frontal plane of the hip and knee joint (p<.05). Females had a significantly smaller initial abduction angle of the hip joint and a significantly greater maximal angle of the hip adduction joint. These results suggest that selecting a sit-to-stand exercise for pelvic tilt posture should be considered to control abnormal movement in the lower extremities.

The purpose of this study was to identify the effects of manual facilitation and a stick on lumbar and hip joint flexion angles in subject with lumbar flexion syndrome during forward bending from a sitting position. Fifteen subjects with lumbar flexion syndrome were recruited for this study. As a pretest, all subjects performed three repetitions of bending the trunk forward until the tips of their fingers touched the target bar. After this pretest, the subjects practiced the forward bending of the trunk 10 times, using either manual facilitation or a stick. Then, as a posttest, all subjects repeated the pretest procedure. The flexion angles of lumbar spine and hip joint during forward bending in a sitting position were measured using a three-dimensional motion analysis system. A paired t-test was used to determine the statistical differences between pre-test and post-test flexion angles and pre- and post-test flexion angle differences between forward bending with manual facilitation and forward bending with a stick. The level of statistical significance was set at p=.05. The results of the study showed that the angle of the lumbar flexion decreased significantly and the bilateral hip flexion angle increased significantly when performing forward bending with stick and manual facilitation. Furthermore, the angle of lumbar flexion decreased significantly and the angle of bilateral hip flexion increased significantly in forward bending with a stick compared to forward bending with manual facilitation. The findings of this study indicate that both forward bending with manual facilitation and sticks could be used to prevent excessive lumbar flexion and increase hip flexion, and that forward bending with a stick is more effective than forward bending with manual facilitation for inducing lumbar spine and hip joint angle changes.

The purpose of this study was to find differences of sergeant jumping performances. The best(GP) & worst(BP) performance of each subject based on their jump height were compared in further analysis. There was a significant difference of approx. 18% in the

The purpose of this study was to investigate the effects of Evjenth-Hamberg stretching on the active range of motion (ROM) of the hip joint and the pennation angle of the semitendinosus muscle. Eighty healthy adults participated in this study. The active ROM of the hip joint was measured by a goniometer and the pennation angle of the semitendinosus muscle was measured by ultrasonographic imaging (USI). Both ROM and pennation angle were recorded before and after the static stretching and the Evjenth-Hamberg stretching, respectively. Data were analyzed using paired t-lest and independent t-test at p<.05. The results were as follows: 1) The active ROM of the hip joint increased significantly after both stretching interventions compared with the baseline (p<.001). However, the active ROM of the hip joint increased significantly in Evjenth-Hamberg stretching compared with static stretching. 2) The pennation angle decreased significantly after both stretching interventions compared with the baseline (p<.001). However, the pennation angle decreased significantly in Evjenth-Hamberg stretching compared with static stretching. 3) Reliability data showed that there was a high consistency in USl measurements (ICC=.978). Our findings suggest that the Evjenth-Hamberg stretching was more effective than static stretching in increasing the active ROM of the hip joint and decreasing the pennation angle of the semitendinosus muscle.

This paper presents the estimation of the frictional coefficient of the wheel-legged robot with hip joint actuation producing maximum tractive force. Slip behavior for wheel-legged robot is analytically explored and physically understood by identification of the non-slip condition and derivation of the torque limits satisfying it. Utilizing results of the analysis of slip behavior, the frictional coefficients of the wheel-legged robot during stance phase are numerically estimated and finally this paper suggests the pseudo-algorithm which can not only estimate the frictional coefficients of the wheel-legged robot, but also produce the candidate of the touch down angle for the next stance.