• Korean Journal of Applied Biomechanics
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• v.13 no.3
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• pp.133-149
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• 2003

The purposes of present study were to determine the major check-points of golf swing from the review of previous studies, and to suggest additional information on the teaching theory of golf. The golf swing motion of 6 male and female elite university golf players were filmed with 16mm Locam II high speed cameras at the speed of 200f/s, and variables such as time, displacement, angle, velocity were calculated and analyzed by 3D Cinematography using DLT method. The results were: 1. Differences were shown in the ratio of weight distribution on the feet, cocking angle, take-back velocity, club-head velocity at impact depending upon the physical characteristics and club used for swing. 2. Time for the down-swing and impact were $0.27{\sim}0.29s$ in men and $0.29{\sim}0.32s$ in women, which was 1/3 of the time for the back-swing. Women showed longer total swing time than men because of longer time in back-swing, follow-through and finish. 3. Men showed larger range of motion in shoulder and knee joints than women, on the other hand women showed larger range of motion in hip joint than men. 4. Cocking motion and right elbow flexion were occurred at the top of back-swing and cocking release was occurred at the moment of impact. Maximum rotations of shoulder and hip joints were found between the top of back-swing and down-swing phase. 5. Women showed lower back-swing velocity than men, and men showed higher club velocity(men: $38.2{\sim}38.6m/s$, women: $35.1{\sim}36.4m/s$) than women.

• Korean Journal of Applied Biomechanics
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• v.17 no.3
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• pp.155-164
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• 2007

This study is aimed at determining the effects of rehabilitation training on lumbar extension strength and relief of back pain in middle-aged women of low back pain. Twenty-nine subjects(total 29 people; CLBP 16, HLD 13) were trained twice per week for eight weeks and completed a maximum isometric test at various flexion angle(the degree of $0^{\circ}$, $12^{\circ}$, $24^{\circ}$, $36^{\icrc}$, $48^{\circ}$, $60^{\circ}$, $72^{\circ}$) by lumbar extension machine. The result showed that. 1. Patient group of CLBP were increased the maximum lumbar extension strength at a range of 7 flexion angles after rehabilitation rather than no rehabilitation(on the average 60.75%). The operated patient group in HLD also showed an increase of 56.55%. In view of these cases, all of two groups showed a significant increase of muscle strength(p<.05). But there is no difference between pre-exercise and post-exercise groups. 2. Patient group of CLBP were increased higher rate than 41% for maximum lumbar extension strength(91.79% at $0^{\circ}$, 79.41% at $12^{\circ}$, 65.89% at $24^{\circ}$) at all angles after 8 weeks training. Both groups indicated a significant increase(p<.05) of lumbar extension strength at all degrees. There is no difference between pre-exercise and post-exercise groups. 3. Relief of back pain in Patient group of CLBP showed a decrease of average 105.2% and patient group of HLD indicated a decrease of average 64.57% two groups showed a significant reduction (p<.05, p<.05). But in case of a decrease of pain, CLBP group got 3.44 points and HLD group got 4.77 points. In view of these results, two groups showed remarkable reduction of back pain, however HLD group had residual pain relatively.

• Journal of Korean Physical Therapy Science
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• v.16 no.3
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• pp.11-17
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• 2009

Background: The purpose of this study was designed to find out the effectiveness of reposition sense, muscle fatigue response on lumbar spine after apply lumbosacral stabilization exercise program to 4 patients with chronic low back pain and for 12 weeks. Method: In this study the reposition sense was measured in 3 angle(60, 30, 12) of the lumbar spine motion with blind by MedX test machine and the difference of instability to lumbar vertebra segments in flexion, extension test of standing position and spinal load test Mattress Test by Spinal Mouse. The stabilization exercise program was applied 2 times a week for 12 weeks in hospital and 2 times a day for 20 minutes at home. Result: The results of the present study were that the repositioning sense was appeared the most error in 12 angles of lumbar flexion and Men was appeared to decrease an error more than female in average value of 4 angles after 12 weeks. And average error of male was decrease more than female. Thus the effects of lumbosacral stabilization exercise was improved repositioning sense of prorioceptor. Fatigue response test(FRT) results, in male, was raised muscle fatigue rate during increase weight, on the other hand female appeared lower than male. Conclusion: As a results, lumbosacral stabilization exercise was aided to improvement of lumbar spine repositioning sense and vertebra segments stabilization. It was showed the rate of decrease in typically 12 degree angle point of each 3 angle(60, 36, 12). Especially, that spine instability patients will have a risk when in lifting a load or working with slight flexion posture around 12 degree during the daily of living life and it is probably to increase recurrence rate. Thus, not only lumbar extension muscle strength but also stability of vertebra segments in lumbar spine may be very important.

• Korean Journal of Applied Biomechanics
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• v.27 no.3
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• pp.157-164
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• 2017

Objective: The purpose of this study was to investigate kinematic differences in back pike somersault in platform diving according to skill level and to apply the findings to improve performance. Method: Korean divers participating in this study were divided into a skilled group (age: $21.6{\pm}4.16y$, height: $1.68{\pm}0.03m$, weight: $62.0{\pm}3.94kg$, career: $12.6{\pm}5.13y$) and a less-skilled group (age: $20.6{\pm}2.7y$, height: $1.72{\pm}0.05m$, weight: $64.8{\pm}6.76kg$, career: $12.2{\pm}2.49y$) and an independent t-test was performed to analyze differences between groups at the moment of takeoff. Results: The two groups showed significant differences in displacement and velocity of center of mass (COM), takeoff angle, hip joint angle, knee joint angular velocity, and hip joint angular velocity at the takeoff (p<.05), and significant differences in displacement of COM, hip joint, and ankle joint during flight (p<.05). Conclusion: For a successful back pike, the COM should rise quickly in the vertical direction and the hip joint angle and angular velocity should increase. To improve performance, the back pike turn should be practiced on the ground before an attempt on a 10-m platform, to stretch the ankle and knee joints and enable quick flexion of the hip joint when turning in flight.

• Journal of the Korean Society of Physical Medicine
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• v.13 no.3
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• pp.1-9
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• 2018

PURPOSE: The purpose of this study was to determine the effect of exercise therapy on low back pain (LBP), the function of paraspinal and abdominis muscles, and the sacrohorizontal angle as seen on the radiographs of the lumbar spine in a young female golf player with LBP. METHODS: This case report describes an 11-year-old female golfer who presented with LBP. The exercise therapy program comprised lumbar joint mobilization, lumbar spine flexion distraction, abdominal bridge, plank, side plank, and single-leg extensions from a 4-point kneeling position for 40 min/day; this was done twice a week for 8-weeks. LBP [visual analog scale (VAS) and Oswestry disability index (ODI)] and function of paraspinal and abdominis muscles [Ito test, curl-up test, $90^{\circ}$ stop test, squat test, opened eye one leg stance test (OEOL), and closed eye one leg stance test (CEOL)] were measured before and after 4 and 8 weeks of exercise therapy. The radiographs were analyzed for the lumbar Cobb's angle and sacrohorizontal angle before and after 8 weeks of exercise therapy. RESULTS: After 4 and/or 8 weeks of exercise therapy, VAS and ODI scores decreased; results for the Ito test, curl-up test, $90^{\circ}$ stop test, squat test, and OEOL and CEOL of muscle function improved; and the lumbar Cobb's angle and sacrohorizontal angle improved. CONCLUSION: These results suggest that exercise therapy improves LBP, muscle function, and radiographic parameters associated with LBP in young golf players. These findings have clinical implications for exercise therapy in young female golf players who have LBP.

• Journal of the Korean Society of Physical Medicine
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• v.16 no.4
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• pp.1-11
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• 2021

PURPOSE: Lumbosacral orthosis (LSO) is often used to help manage low back pain because it is economical and effective. This study examined the effects of flexible and semirigid LSOs on the lower-limb joint angles in walking in patients with chronic low back pain. METHODS: The effects of the lumbosacral orthosis during gait on the sagittal, frontal, horizontal planes and the change in lower limb angle were examined in fourteen chronic low back pain patients who walked without wearing a LSO, wearing a flexible LSO, and wearing a semirigid LSO in random order for three-dimensional motion analysis. RESULTS: The flexion of the hip and knee joints decreased more significantly during walking with an LSO than without one. The genu valgum angles were reduced in the stance phase more during walking with an LSO than without one. The external rotation of the knee joints in the stance phase increased more during walking with an LSO than without one. CONCLUSION: The angles of the lower-limb joints of patients with chronic low back pain are affected by walking with an LSO, and the effects increased as the LSO stiffened.

• Physical Therapy Korea
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• v.10 no.3
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• pp.29-40
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• 2003

The purpose of this study was to compare the muscle activity during a push-up on a suspension sling and a fixed support at the same level. Tests were performed on 15 male subjects. Electromyography using a surface EMG recorded the activity of the triceps, pectoralis major, and internal and external oblique muscles during each push-up. EMG activity was recorded at 0, 45, and 90 degrees of elbow flexion in the push-up position on a suspension sling or a fixed support at the same height above the floor (30 cm). The testing order was selected randomly. The subjects were asked to maintain the push-up position with straight knees, hips, and trunk for 5 seconds at each elbow angle. The mean root mean square (RMS) of EMG activity was calculated. EMG activity was normalized using the maximum voluntary isometric contractιn elicited using a manual muscle testing technique. Two-factor repeated measures analysis of variance (ANOVA) was used to compare the average RMS value of EMG activity for each condition. The EMG activity for the pectoralis major, and internal and external oblique muscles during a push-up on a sling was significantly higher than on a fixed support at all angles of elbow flexion (p<.01). There were significant differences in the EMG activity of the pectoralis major and triceps brachii muscles at difference angles of elbow flexion (p<.05). The pectoralis major muscle had the highest EMG activity at 90 degrees of elbow flexion on both the sling and fixed support. The triceps brachii muscle had the highest EMG activity at 45 degrees of elbow flexion on both the sling and fixed support. The internal and external oblique muscles had the highest EMG activity at 0 degrees of elbow flexion, although the difference with angle of flexion was not significant. These results suggest that to improve proximal and trunk stability and muscle strength, push-ups are more useful when performed on a suspension sling than On a fixed support.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.13 no.2
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• pp.12-20
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• 2007

The purpose of this study was designed to find out the effectiveness of vertebral segment instability, muscle fatigue response on lumbar spine after apply lumbosacral stabilization exercise program to 4 patients with chronic low back pain and for 12 weeks. In this study, the lumbar spine motion with blind by MedX test machine and the difference of instability to lumbar vertebra segments in flexion, extension test of standing position and spinal load test(Matthiass Test) by Spinal Mouse. The stabilization exercise program was applied 2 times a week for 12 weeks in hospital and 2 times a day for 20 minutes at home. The results of the present study were as follows: 1. Instability test of lumbar vertebra segment is 2 type differential angle test between vertebrae segment and loading test of spine(matthiass) by Spinal Mouse. It appeared to improve stability of segments in sagittal plane after applying program. So lumbar spine curve increased lordosis toward anterior and was improved of the lumbar spine flexibility in flexion and extension. Specially, in matthiass test, (-) value was increased between lumbar vertebra segment when was the load on spine. And so applying stability improved after program. 2. Fatigue response test(FRT) results, in male, was raised muscle fatigue rate during increase weight, on the other hand female appeared lower than male. As a results, lumbosacral stabilization exercise was aided to improvement of lumbar spine vertebra segments stabilization. Spine instability patients will have a risk when in lifting a load or working with slight flexion posture during the daily of living life and it is probably to increase recurrence rate. Thus, not only lumbar extension muscle strength but also stability of vertebra segments in lumbar spine may be very important.

• Journal of Korean Physical Therapy Science
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• v.13 no.4
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• pp.7-16
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• 2006

The purpose of this study was designed to find out the effectiveness of vertebral segment instability, muscle fatigue response on lumbar spine after apply lumbosacral stabilization exercise program to 4 patients with chronic low back pain and for 12 weeks. In this study, the lumbar spine motion with blind by MedX test machine and the difference of instability to lumbar vertebra segments in flexion, extension test of standing position and spinal load test(Matthiass Test) by Spinal Mouse. The stabilization exercise program was applied 2 times a week for 12 weeks in hospital and 2 times a day for 20 minutes at home. The results of the present study were as follows: 1. Instability test of lumbar vertebra segment is 2 type differential angle test between vertebrae segment and loading test of spine(matthiass) by Spinal Mouse. It appeared to improve stability of segments in sagittal plane after program. So lumbar spine curve increased lordosis toward anterior and was improved of the lumbar spine flexibility in flexion and extension. Specially, in matthiass test, ( - ) value was increased between lumbar vertebra segment when was the load on spine. And so stability improved after program. 2. Fatigue response test(FRT) results, in male, was raised muscle fatigue rate during increase weight, on the other hand female appeared lower than male. As a results, lumbosacral stabilization exercise was aided to improvement of lumbar spine vertebra segments stabilization. Spine instability patients will have a risk when in lifting a load or working with slight flexion posture during the daily of living life and it is probably to increase recurrence rate. Thus, not only lumbar extension muscle strength but also stability of vertebra segments in lumbar spine may be very important.

• Steel and Composite Structures
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• v.3 no.4
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• pp.261-275
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• 2003

Truss members built-up with double angles back-to-back have monosymmetric cross-section and twisting always accompanies flexion upon the onset of buckling about the axis of symmetry. Approximate formulae for calculating the buckling capacity are presented in this paper for routine design purpose. For a member susceptible only to flexural buckling, its optimal cross-section should consist of slender plate elements so as to get larger radius of gyration. But, occurrence of twisting changes the situation owing to the weakness of thin plates in resisting torsion. Criteria for limiting the leg slenderness are discussed herein. Truss web members in compression are usually considered as hinged at both ends for out-of-plane buckling. In case one (or both) end of member is not supported laterally by bracing member, its adjoining members have to provide an elastic support of adequate stiffness in order not to underdesign the member. The stiffness provided by either compression or tension chords in different cases is analyzed, and the effect of initial crookedness of compression chord is taken into account. Formulae are presented to compute the required stiffness of chord member and to determine the effective length factor for inadequately constrained compressive diagonals.