• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.12
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• pp.8684-8690
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• 2015

This study aimed to investigate the influence of the ankle dorsiflexion angle ($0^{\circ}$, $10^{\circ}$, and $20^{\circ}$) on the effectiveness of gastrocnemius stretching angle. The subjects of this study were 25 young man and female women. In all participants, the pennation angle of the medial head of the gastrocnemius was evaluated using ultrasonography at an ankle dorsiflexion angle of $0^{\circ}$, $10^{\circ}$, or $20^{\circ}$. Repeated measures analysis of variance was uesd to test for differences between ankle dorsiflexion angles. The independent t-test was performed to determine the significance of sex differences. The results of this study showed that the gastrocnemius pennation angle decreased as the ankle dorsiflexion angle increased, with significant interaction between each angle of ankle dorsiflexion angle (p<0.01). Sex comparison showed that the pennation angle was greater in man than in women, but the difference was not significant (p>0.05). According to the sex the gastrocnemius pennation angle is decreased as the ankle dorsiflexion angle increased (p<0.01). These results suggest that the end range of dorsiflexion is more beneficial for gastrocnemius stretching than a small range. Further studies are needed to investigate the influence of other factors, such as stretching angle and application time, on gastrocnemius stretching.

• Journal of International Academy of Physical Therapy Research
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• v.11 no.3
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• pp.2102-2106
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• 2020

Background: Static hamstring stretching exercises have been widely used to improve flexibility of the hamstring muscles. However, few studies have examined the influence of standing static hamstring stretching (e.g., jack-knife stretching) on movements of the lumbopelvic-hip complex. Objectives: To examine the short-term effects of jack-knife stretching on movements of the lumbopelvic-hip complex. Design: Case series. Methods: Fourteen participants with hamstring tightness (8 male, 6 female) were recruited. Participants performed jack-knife stretching for 150 s. Before and after stretching, participants performed the finger-to-floor distance (FFD), sit and reach (SRT), active knee extension (AKE), passive straight leg raising (PSLA), and active straight leg raising (ASLR) tests as well as pelvic tilt while standing to identify the effects of stretching. Results: There were significant improvements in the FFD, SRT, AKE, PSLA, and ASLR tests after stretching. However, pelvic tilt angle while standing did not significantly change. Conclusion: Jack-knife stretching can be a useful exercise to improve flexibility of the hamstring muscles, but not pelvic alignment while standing.

• Physical Therapy Korea
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• v.27 no.1
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• pp.30-37
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• 2020

Background: To prevent or reduce the risk of strain injury, various approaches, including stretching techniques are currently being used. The effect of proprioceptive neuromuscular facilitation (PNF) and static stretching on flexibility has been demonstrated; however, it is not clear which one is superior. Objects: This study aimed to evaluate the differences between the effects of PNF and static stretching performed at various intensities on muscle flexibility. Methods: The maximum voluntary isometric contraction (MVIC) of the hamstrings using the PNF stretching technique was performed in the P100 group, while 70% of the MVIC was performed in the P70 group. The MVIC value obtained during the PNF stretching in both groups was used as a reference for setting the intensity of static stretching. Static stretching was performed at 130% (S130), 100% (S100), and 70% of the MVIC (S70). The active knee extension (AKE) values, defined as the knee flexion angle were measured before stretching (baseline), immediately after stretching (post), and at 3 minutes, 6 minutes, and 15 minutes. Results: PNF stretching produce a greater improvement in flexibility compared with static stretching. Specifically, the ΔAKE was significantly higher in the S100 and S70 groups than in the P100 group at Post. In the comparison of ΔAKE over time in each group, the ΔAKE at Post showed a significant decrease compared to the value at Baseline in the S130 group; however, no significant difference was observed at 6 minutes while a significant increase was noted at 15 minutes. Conclusion: This study found that PNF stretching is more effective than static stretching with respect to increasing and maintaining the flexibility of muscles. In addition, the increase in flexibility at maximal intensity was similar to that observed at submaximal intensity during both PNF and static stretching.

• The Journal of Korean Physical Therapy
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• v.22 no.1
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• pp.1-7
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• 2010

Purpose: Stretching exercises are commonly used in conjunction with sports and rehabilitation. Weassessed the immediate effects of stretching on passive stiffness of the hamstring muscles and knee range of motion (ROM) using three stretching techniques. Methods: A total of 45 participants were recruited. Isokinetic equipment was used to measure the passive stiffness of hamstring muscles and an inclinometer was used to measure active and passive ROM of the knee joint pre and post stretching. Stiffness was then calculated based on the incline of the torque-angle relationship. The test conditions for Group I were $3{\times}30$ seconds of static stretches using the hamstring muscle, Group II were $3{\times}30$ seconds of static stretches using the hamstring muscle with ankle dorsiflexion, and Group IIII had $3{\times}30$ seconds of active stretching. Results: Group II had significantly higher excursion of active ROM and Group IIIhad significantly higher excursion of passive muscle stiffness. All of the groups had significantly higher active and passive ROM and significantly lower muscle stiffness after stretching. The participants showed no change in hamstring muscle stiffness on the following day. Conclusion: Stretching has significant acute effects on ROM and muscle stiffness and canbe used in warm-up protocols for reducing muscle stiffness before a variety of exercise programs.

• The Journal of the Korea Contents Association
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• v.11 no.10
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• pp.293-300
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• 2011

This study was to find out the effect of cervical and thoracic stretching and strengthening exercise program on forward head posture. 32 adults had forward head posture were selected as the subjects for the study. The training program of the exercise group(n=16) consist of postural education with exercise program, subjects in the control group(n=16) participated in a postural education only. Postural measurements of Craniovertebral Angle(CVA) and Cranial Rotation Angle(CRA) were obtained from the using x-ray and PACS(Picture Archiving and Communications System) ${\pi}view^{TM}$. The results were compared with change of CVA and CRA exercise group were significant(p<.05) compared to the control group. However CRA of contol group was significant(P<.05). Also, there were no significant difference(p>.05) between groups on any pre-test measure. however there were significant difference(p<.05) between groups on CVA and CRA post-test measure. This study showed that cervical and thoracic stretching and strengthening exercise program can improve spinal posture alignment for decreasing forward head posture in subjects. These results can be fundamental data for further development of exercise program in interventions of postural improvement.

• Physical Therapy Korea
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• v.24 no.2
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• pp.9-18
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• 2017

Background: Limitation of hamstring extensibility is often associated with various musculoskeletal problems such as alterations in posture and walking patterns. Thus, certain appropriate strategies need to be established for its management. Objects: The aim of this study was to compare the effects of the neural mobilization technique and static stretching exercises on popliteal angle and hamstring compliance in young women with short hamstring syndrome (SHS). Methods: Thirty-three women with SHS were randomly assigned to either group-1 ($n_1=17$) that underwent the neural mobilization technique or group-2 ($n_2=16$) that underwent the static stretching exercises. Outcome measures included the active popliteal angle (APA) and a hamstring's electromyographic (EMG) activity at a maximum popliteal angle of the baseline. Intervention for each group was performed for a total time of 3-min (6 sets of a 30-sec application). Results: There were significant interactions between time and group in the APA [group-1 (pre-test to post-test): $69.70{\pm}8.14^{\circ}$ to $74.14{\pm}8.07^{\circ}$ and group-2: $68.66{\pm}7.42^{\circ}$ to $70.52{\pm}7.92^{\circ}$] (F1,31=6.678, p=.015) and the EMG activity of the hamstring (group-1: $1.12{\pm}.30{\mu}N$ to $.69{\pm}.31{\mu}V$ and group-2: $1.19{\pm}.49{\mu}V$ to $1.13{\pm}.47{\mu}V$)(F1,31=6.678, p=.015). Between-group comparison revealed that the EMG activity of the hamstring was significantly different at post-test between the groups (p<.05). Furthermore, in within-group comparison, group-1 appeared to be significantly different for both variables between pre- and post-test (p<.05); however, group-2 showed significant difference in only the APA between pre- and post-test (p<.05). Conclusion: These findings suggest that the neural mobilization technique and static stretching exercises may be advantageous to improve hamstring compliance in young women with SHS, resulting in a more favorable outcome in the neural mobilization technique.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.05a
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• pp.400-403
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• 2004

A non-heat기leafed steel does not need quenching and tempering processes that are called a heat treatment differently from conventional steel. Since the tensile strength of this steel is higher than 900MPa, a conventional forming process should be changed to incremental forming process such as a cross wedge rolling that requires lower load capacity than conventional ones. In this paper, the cold cross wedge rolling (CWR) die has been designed using CAD/CAE In order to produce near-net-shaped component of ball stud of non-heat-treated cold steel. Finite element analyses were applied in order to investigate process parameters of CWR. Results provide that the stretching angle and the forming angie at knifing zone in CWR process is important parameter to be the stable process under the low friction coefficient condition.

• Korean Journal of Applied Biomechanics
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• v.18 no.4
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• pp.41-47
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• 2008

The purpose of this study was to provide foundations for proper stretching method not to lose muscle strength caused by shrink of muscle for preventing injury and improving performance when we make training programs. This study compared and analyzed isokinetic variables related to the static stretching frequency of knee joint extensor by isokinetic instruments applied to normal adults. 45 normal adults are randomly sampled into 3 different groups. All the measured variables were processed with SPSS and, means and standard deviations at each angle speed were calculated. The difference of means between before and after stretching of each groups were processed by paired t-test. One-way ANOVA and after test(Duncan) This study was able to see that stretching decrease acute isokinetic muscle strength High frequency stretching group showed more efficient decrease of muscle strength than low frequency stretching group. As a result, making training program for a game requiring strong muscle strength should consider proper stretching method not to lose muscle strength.

• Journal of Korean Physical Therapy Science
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• v.24 no.2
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• pp.45-52
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• 2017

Purpose : Most of the moderns have been spent sedentary life style in front of desk or on the chairs, so that their hamstring muscles are shorted commonly and the shortness of hamstring muscles are caused to some problems in functional activities. The purpose of this study was to compare the effectiveness of thermotherapy with hot-pack and ultrasound on the tightness of hamstring muscles in individuals with hamstring tightness. Method : Twenty-eight persons with hamstring tightness participated in this study. They were randomly assigned to three exercise groups: stretching group(n=10), hot-pack group(n=9), and ultrasound group(n=9). Before experiment, this study measured the angle of hip flexion using a inclinometer in all participants. Stretching group conducted actively stretching on their shorted leg for 30 seconds, 3 times, and rest for 10 seconds between each exercises. Hot-pack group have applied hot-pack($70{\sim}75^{\circ}C$) on shorted hamstring muscles for 20 minutes before stretching exercise. Ultrasound group have applied therapeutic ultrasound(1 MHz and 1.5W/cm2) on shorted hamstring muscles for 10 minutes before stretching exercise. All data was analysed using one-way repeated ANOVA. Result : The results revealed that ultrasound therapy before stretching is more effective to the flexibility on hamstring muscles than hot-pack before stretching and stretching only. Conclusion : The results of this study show that thermotherapy with therapeutic ultrasound will be effective on the shortness of hamstring muscles before stretching exercise.

• The Journal of Korean Physical Therapy
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• v.23 no.1
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• pp.29-35
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• 2011

Purpose: The purpose of this study was to identify the effect of neck exercises on neck-shoulder posture and pain of high school students with neck disorders. Methods: Twenty seven subjects were randomly assigned to one of 3 groups a craniocervical flexion training group (CCFT), a neck strengthening exercise group (ST), and a basic stretching exercise group (CG). CCFT and ST exercised five times a week for eight weeks under the researcher's guidance. The control group performed basic stretching exercises. Diagnostic radiologic equipment was used for the measurement of neck-shoulder posture. Neck disability index, and numeric rating scales were used. Results: The CCFT showed a significant pre-post treatment difference on measures of neck flexion angle and forward shoulder angle changes compared to the ST and CG groups (p<0.05). The CCFT group also showed a significantly greater improvement on the neck disability index and numeric rating scales changes than the ST and CG groups (p<0.01). Conclusion: Because CCFT decreases neck flexion angle, forward shoulder angle, neck disability index, and pain in the forward head posture, it is useful for treating patients with neck disorders.