• Journal of the Ergonomics Society of Korea
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• v.22 no.4
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• pp.47-57
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• 2003

This study investigated the recruitment patterns of ten trunk muscles in isometric exertion tasks, focused on the functional roles (agonist or antagonist). Twelve male students performed maximum voluntary isometric exertion tasks towards six directions: flexion/extension, left/right lateral bending, and clockwise/counter-clockwise twisting. EMG signals from ten trunk muscles and exertion forces were collected. Normalized EMG (NEMG) values were calculated at 10, 20, 30, 40, 50, 60, 70, 80, and 90 %MVC. The subjects showed a limited capacity in producing twisting moments, approximately 50% of the extension moment, and 70% of lateral bending moments. EMG activity was dependent on the direction and magnitude of the exertion, and also on the functional role. The mean NEMG of agonist was 0.260 and 0.067 for antagonist. Agonists showed the highest mean NEMG in flexion (0.367), while antagonists showed the highest mean NEMG in twisting clockwise/counter-clockwise (0.090/0.106).

• Korean Journal of Applied Biomechanics
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• v.16 no.1
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• pp.159-166
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• 2006

The purpose of this study were analysed fatigue character of lumbar extension Muscle during repeated trunk flexion-extension motion we used EMG multi-telemeter (WEB 5000, Nihon Koden, Japan), Medex lumbar extension machine(Ocala, USA). We evaluated 20 persons on chronic low back pain group and 20 persons on control group. We analysed the quantitative variables IMF, MF, decreased ratios of MF to investigate fatigue. As a result, the following conclusion was drawn : 1. Each lumbar IMF of CLBP was L5> L3> L1 in the order of their size. CON group was similar quantitative and same order. But the relationship of two groups were not significantly. 2 The IMF within lumbar position(L1-L3, L1-L5, L3-L5) of two groups was significantly all positions(p<.05). 3. The MF shifting at lumbar position of two groups during repeated trunk flexion-extension motion was decrease shifting pattern with increase repeating motion, especially CLBP group was suddenly dropping than CON at all lumbar positions(L1, L3, L5) on early stage motion(34 set). 4. The lumbar fatigue of CLBP was higher than CON during repeated trunk flexion-extention motion, so CLBP supposed more tired than CON. And it was significantly within two groups at lumbar positions(L1, L3 : p<.05, L5 : P<.01).

• Journal of Korea Entertainment Industry Association
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• v.14 no.8
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• pp.245-253
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• 2020

This study has conducted to investigate the changes in the mobility of the three thoraco-abdominal lines(TAMs) during breathing and in the thoracic and lumbar spine mobility(TSM, LSM) during trunk forward flexion, after breathing pattern correction. The 30 subjects with lumbar instability(LI) have divided into the breathing pattern correction exercise(BPC) group of 15 subjects and the lumbar stabilization exercise(LSE) group of 15 subjects and performed each exercise for 40 minutes at one session, and a total of 18 sessions were applied for 6 weeks. As a result, The BPC group during breathing showed a significant increase in all TAMs(p<.001) and in the TSM(p<.001) than the LSE group. Besides, had a more decrease in the LSM than the LSE group(p<.001). The BPC showed high positive correlations with TAMs(rest: r=.868, forced: r=.870) and the TSM(r=.672) and had a negative correlation with the LSM(r=-.420). Based on this result of the study, the authors believe that the BPC in LI people could decrease the lumbar flexion mobility when they have motion of trunk forward flexion with promotions in the thoracic spine and rib joint mobility by improvements in relative mobility of thoraco-abdominal lines.

• Journal of the Korean Academy of Clinical Electrophysiology
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• v.7 no.1
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• pp.43-48
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• 2009

Purpose : The purpose of this study was to study the effect of rectus abdominal muscle contraction by proprioceptive neuromuscular facilitation trunk stabilization training using extremity simultaneous pattern (PNF trunk stabilization training) and traditional trunk stabilization training methods. Methods : A group of 24 adults male and female, healthy, with no previous medical history nor disability in neuromuscular system and musculoskeletal system was chosen as subjects, and was divided into a control group, a PNF trunk stabilization training group and a traditional trunk stabilization training group. Experiments were performed on the last two groups, 3 times a week for 6 weeks, totaling 18 times. Using a dynamometer, muscle strength and endurance time on trunk flexion were measured before and after each experiment, and surface electromyography in left and right rectus abdominis were measured. Results : following results were obtained; 1. As for the change in the maximal voluntary isometric contraction (MVIC), all subjects in the trunk stabilization training group showed significant difference from those in the control group. 2. As for surface electromyography measurement and the changes in root mean square at the time of trunk flexion, in the left rectus abdominis, PNF trunk stabilization training group showed significant difference from the control group, while in the right rectus abdominis, traditional trunk stabilization training group showed significant difference. Conclusion : To sum up the results, both trunk stabilization training groups showed improvement in the MVIC of abdominal muscle, motor unit action potential activity, but the difference between two trunk stabilization training groups was not significant. Therefore, while trunk stabilization training significantly improved abdominal muscle contraction, but the difference attributable to training methods was found to be insignificant.

• Physical Therapy Korea
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• v.14 no.1
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• pp.21-27
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• 2007

The purpose of this study was to evaluate isometric trunk extension strength in hemiplegic patients, and to compare that with normal subjects to find a correlation between trunk extension strength and the functional independent degree in hemiplegic patients. Fifteen hemiplegic male patients (mean age $55.2{\pm}10.2$ years) and twenty-five healthy male subjects (mean age $54.6{\pm}10.3$ years) completed isometric trunk extension. Strength was measured at 0, 12, 24, 36, 48, 60, and 72 degrees of trunk flexion. The functional independent degree was assessed by Functional Independence Measure (FIM). Mean isometric trunk extension strength was 91.2 ft-lbs, 120.7 ft-lbs, 142.3 ft-lbs, 156.4 ft-lbs, 173.5 ft-lbs, 184.1 ft-lbs, and 195.3 ft-lbs in the hemiplegic patients group, and 135.6 ft-lbs, 175.6 ft-lbs, 204.4 ft-lbs, 221.9 ft-lbs, 231.2 ft-lbs, 246.8 ft-lbs, and 259.7 ft-lbs in the normal subjects group. The values of isometric trunk extension strength had a descending linear correlation pattern from trunk flexion angle to extension angle. Trunk extension strength in hemiplegic patients was significantly lower than that of normal subjects (p<.05) but did not correlate with the FIM total score (p>.05). Therefore, the isometric trunk extension strength in hemiplegic patients was lower than that of normal subjects and did not correlate with the functional independent degree.

• Korean Journal of Applied Biomechanics
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• v.21 no.3
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• pp.281-288
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• 2011

The purpose of this study was to analyze the difference in reaction patterns during the support phase after perturbation in gait according to different age. A total of 12 subjects participated; 5 elderly and 7 adults(control), to investigate the differences between normal and perturbed gait. The step length didn't change during normal and perturbed gait but was longer in the control group. There was no difference in the step width. When the right foot was perturbed, the control group's left foot speed was faster than the elderly group's which was to maintain stability. The elderly flexed both right and left knees more than the control group. After the perturbation, the elderly group had a larger trunk anterior flexion. With the larger flexion of both legs of the elderly group it shows that the lack of knee flexion strength is a factor, that could cause falling and so a prevention program should focus on strengthening the quadriceps. With the excessive trunk flexion after the perturbation by the elderly group observed, it is suggested that while walking everyday a good routine of walking with an upright posture should be developed.

• PNF and Movement
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• v.15 no.3
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• pp.237-246
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• 2017

Purpose: The purpose of this study was to investigate the effects of forward-and-backward shift trunk exercise using a proprioceptive neuromuscular facilitation (PNF) diagonal pattern in a closed kinematic chain exercise on the upper limb function and activity of daily living (ADL) in a stroke patient. Methods: One subject participated in this study. The study used a reversal A-B-A' design, where A and A' were the baseline period (no intervention), and B was the intervention period. The intervention was a forward-and-backward trunk shift exercise, using a PNF diagonal pattern on both a stand-on-hand position and a quadruped position of closed kinematic chain exercises, for 20 min per day for 2 weeks. The range of motion (ROM) of the shoulder joint was measured and a Fugl-Meyer assessment of upper extremity (FMA-UE) and a functional independence measure (FIM) were performed to measure upper limb function and activity of daily living (ADL). Results: ROMs of shoulder joint (flexion, extension, abduction, and external rotation) increased in the intervention phase. The FMA-UE score increased (from 28 to 36) in the intervention phase. The FIM score increased (from 20 to 25) in the intervention phase. These increases were maintained after intervention (Baseline II). Conclusion: These results suggest that forward-and-backward shift trunk exercises using a PNF diagonal pattern in a closed kinematic chain exercise have a positive effect on stroke patients' upper limb function and ADL ability.

• PNF and Movement
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• v.14 no.1
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• pp.1-6
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• 2016

Purpose: The purpose of this study was to analyze the effects of proprioceptive neuromuscular facilitation (PNF) patterns on electromyography (EMG) activity in the rectus abdominis, internal abdominal oblique, external abdominal oblique, and erector spinae according to position changes. Methods: Ten healthy adults volunteered to participate in the study. The subjects were required to complete exercises that followed two PNF extremity patterns, namely, an upper extremity extension-adduction-internal rotation pattern and a lower extremity flexion-adduction-external rotation pattern. The exercises were applied in the supine, side-lying, and sitting positions. Repeated measure one-way ANOVA and post-hoc Bonferroni correction were used to determine the influence of the patterns on muscle activity for each muscle, and descriptive statistics were then used to determine the local/global muscle ratios. Results: The upper extremity pattern had a significant effect on the rectus abdominis and erector spinae in the supine position, and on the internal oblique and external oblique in the sitting position (p<0.05). The median value for the internal oblique/rectus abdominis showed a high ratio of 2.05, and a high ratio of 1.01 was shown for the internal oblique/external oblique in the sitting position. The lower extremity pattern had a significant effect on the rectus abdominis in the side-lying position and on the internal oblique, external oblique, and erector spinae in the sitting position (p<0.05). The median value for the internal oblique/rectus abdominis showed a high ratio of 2.83 in the sitting position and a high ratio of 1.30 for the internal oblique/external oblique in the side-lying position. Conclusion: The PNF pattern increases local muscle activation in an unstable position. Therefore, when the pattern is used for intervention purposes, trunk stability and varied position changes should be taken into account.

• Korean Journal of Applied Biomechanics
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• v.17 no.4
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• pp.73-82
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• 2007

The purpose of this study was to qualitatively analyze coordination pattern of joints and segments during Dwichagi in Taekwondo and present a point of difference as compared with the previous study on Dolryeochagi in Taekwondo. By the utilization of three-dimensional cinematography, the angles of individual joints and segments of six male Taekwondo experts during Dwichagi were calculated by using Euler's angle. The used coordination variables were angle vs. angle plots between adjacent joints and segments and angle vs. angular velocity plots of individual joints and segments, respectively. It was observed during Dwichagi that in-phase coordination and spring-like rotational control mechanism of the lower and upper trunk were transferred into straight spring-like control mechanism of lower leg passing through flexion-extension and the fixation of degree-of-freedom of lower trunk and hip joint alternatively. This comparative study that coordination variables were used seems to be more useful research direction to deeply understand basic control mechanisms of Taekwondo kicking techniques when compared with the previous studies that defined Dwichagi as a thrust movement pattern merely based on biomechanical variables of a kicking leg.

• Physical Therapy Rehabilitation Science
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• v.8 no.4
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• pp.175-186
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• 2019

Objective: Non-specific chronic low back pain (NS-CLBP) has been related to abnormal trunk muscle activations, but literature reported considerable variability in muscle amplitudes of NS-CLBP patients during prolonged sitting periods. Therefore, the purpose of this study was to examine the differences among homogenous NS-CLBP subgroups in muscle activity, using muscle co-contraction indices as a more objective approach, and their roles on pain development during a 1-hour period of prolonged sitting. Design: Cross-sectional study. Methods: Twenty NS-CLBP subjects with motor control impairment (MCI) [10 classified as having flexion pattern disorder, and 10 with active extension pattern disorder], and 10 healthy controls participated in the study. Subjects followed a 1-hour sitting protocol on a standard office chair. Four trunk muscle activities including amplitudes and co-contraction indices were recorded using electromyography over the 1-hour period. Perceived back pain intensity was recorded using a numeric pain rating scale every 10 minutes throughout the sitting period. Results: All study groups presented with no significantly distinctive trunk muscle activities at the beginning of sitting, nor did they change over time when pain increased to a significant level. Both MCI subgroups reported a similarly significant increase in pain behavior through mid-sitting (p<0.001). However, after mid-sitting, they significantly differed from each other in pain (p<0.01) but did not differ in the levels of muscle activation. Conclusions: This study was the first to highlight the similarities in trunk muscle activities among homogenous NS-CLBP patients related to MCI and compared them to healthy controls while sitting for an extended period of time, and the significant increase in pain over the 1-hour sitting might not be attributed to trunk muscle activation.