Background: Lower back pain (LBP) is a major cause of disability and a common musculoskeletal disorder encountered at some point in life. Dysfunction of the lumbar vertebrae has been associated with decreased flexibility of the hamstrings, which exhibited a strong positive correlation with LBP. Hamstring tension affects lumbar pelvic rhythm. We aimed to activate pelvic stability with compression by Active Therapeutic Movement (ATM), muscle energy technique (MET) was applied to increase the flexibility of the hamstring. Objects: In this study, we aimed to investigate the effects of MET with ATM and general MET were applied to the hamstring of adults, who were in their twenties with nor without LBP, on their pelvic inclination and the length of their hamstring. Methods: A total of 32 subjects were briefed about the purpose of this study and agreed to participate voluntarily. Before the experiment, all subjects were pre-examined, and they were divided into an LBP group and a no lower back pain group accordingly. Thereafter, all subjects participated in both in a crossover manner. After at least one week, they switched to another group and participated in the same experiment. Results: The study results revealed that both groups demonstrated significant results in the modified active knee extension test (p < 0.01) and the sit and reach test (p < 0.01) performed to assess the hamstring flexibility; an interaction (p < 0.05) was noted. Moreover, a more significant difference was observed between the MET with ATM and the general MET. Although significant results were obtained for the pelvic inclination (p < 0.01), interaction was not noted. Conclusion: Conclusively, in this study, when the MET with ATM was applied to the two groups, there was a significant difference compared to the general MET for hamstring flexibility, but it was confirmed that there was no significant difference for the pelvic inclination.

Background: Although rectus femoris (RF) eccentric training and static stretching (SS) have been reported effectively on lumbar flexibility, and muscle architecture, most studies are results using machines and long-term effects. Therefore, we want to investigate the effect of Reverse Nordic Hamstring Exercise (RNHE), a self-eccentric training, by immediately comparing it with SS. Objectives: To compare the RNHE and SS of RF to show the effects of lumbar flexibility, and fascicle length (FL). Design: Randomized controlled trial. Methods: A total of 30 study subjects were randomly allocated into an experimental group(Reverse Nordic Hamstring Exercise) and a control group(Static Stretching). Before and after the intervention, the subject performed fingertip to floor test (FFT) to evaluate the flexibility of the lumbar spine and measured FL through the SONON 300L (Healcerion Inc., Seoul, South Korea). Results: There was a significant effect on lumbar flexibility within both groups (P<.05), also there were clear results between the two groups (P<.05). FL showed a significant increase in RNHE (P<.05), but not in SS, and there was a no significant difference between the two groups. Conclusion: RNHE is effective in improving lumbar flexibility, and FL of RF muscle.

Background: The flexion-relaxation phenomenon (FRP) refers to a sudden onset of activity in the erector spinae muscles that recedes or fades during full forward flexion of the trunk. Lumbar spine and hip flexion are associated with many daily physical activities that also impact trunk flexion. Shorter hamstring muscles result in a reduction of pelvic mobility that eventually culminates in low back pain (LBP). Many studies have explored the FRP in relation to LBP. However, few studies have investigated the influence of hamstring muscle length on the FRP in relation to the erector spinae muscles during trunk flexion. Objects: This study aimed to investigate the influence of hamstring muscle length on the FRP in relation to the erector spinae muscles during trunk flexion. Methods: Thirty subjects were divided into three groups according to hamstring length measured through an active knee extension test. The 30 participants consisted of 10 subjects who had a popliteal angle of 20˚ or less (Group 1), 10 subjects who had a popliteal angle of 21˚–39˚ (Group 2), and 10 subjects who had a popliteal angle of 40˚ or more (Group 3). A one-way analysis of variance was used to compare the difference in muscle activity of the erector spinae muscles during trunk flexion. Results: The subjects with a shorter hamstring length had significantly higher muscle activity in their erector spinae muscles during trunk flexion and full trunk flexion (p < 0.05). The subjects with a shorter hamstring length also had a significantly higher flexion-relaxation ratio (p < 0.05). Conclusion: The results of this study demonstrate that differences in hamstring muscle length can influence the FRP in relation to the erector spinae muscles. This finding suggests that the shortening of the hamstring might be associated with LBP.

Background:Rounded shoulder posture (RSP), a postural abnormality, might cause shoulder pain and pathologic conditions. Although most previous research has investigated RSP focusing on the proximal structures of the shoulder, such as the scapula and pectoralis muscles, the relationship between RSP and anterior distal structures of the upper extremity, such as the biceps brachii muscle and elbow joint, is not clearly understood.Objects:This study aimed to investigate the correlations between RSP and the biceps brachii length, elbow joint angle (EJA), pectoralis minor length, general pectoralis major length, humeral head anterior translation (HHAT), glenohumeral internal rotation (IR), external rotation (ER), and horizontal adduction (HAD).Methods:Twelve subjects with RSP (6 male, 6 female) were recruited. All subjects fulfilled the RSP criteria indicated by a distance ≥2.5 cm from the posterior aspect of the acromion to the table in the supine position. The examiner measured each of the following parameters twice: RSP, biceps brachii length, EJA, pectoralis minor length, pectoralis major length, HHAT, glenohumeral IR, ER, and HAD. Pearson’s correlation coefficient(r) was used to assess the correlation between RSP and all the variables.Results:There was a significant moderate positive correlation between RSP and biceps brachii length (r=.55, p=.032), moderate negative correlation between RSP and pectoralis minor length (r=-.62, p=.015), and moderate positive correlation between RSP and HHAT (r=.53, p=.038).Conclusion:The biceps brachii length, pectoralis minor length, and HHAT could be used to evaluate patients with RSP. Better understanding of the correlation between these factors and RSP could help in the development of effective methods to treat patients with this condition in clinical management.

The purpose of this study was to find the difference in muscle firing rate between each muscle according to the knee angle with the quadriceps femoris which is a representative action muscle of the lower extremity. Seven normal healthy subjects were recruited. The median frequency (MDF) of muscle contraction was recorded from vastus lateralis, vastus medialis, and rectus femoris muscles using the surface EMG, in 5 seconds, during maximal isometric knee extension. The data were analyzed by the two-way repeated ANOVA. The results of the study were as follows: 1) median frequency of muscle contraction was significantly higher at the vastus lateralis, vastus medialis, and rectus femoris in descending order. 2) median frequency of muscle contraction was significantly higher at the , , and in descending order. Consequently, muscle recruitment at the knee decreases the EMG activity of the lengthened muscle. This study suggests that the change in EMG activity at different muscle lengths resulted in affecting the muscle firing rate during the knee extension.