• Journal of the Ergonomics Society of Korea
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• v.18 no.1
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• pp.55-69
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• 1999

It is very common to use the powered hand tools to enhance the productivity in various types of industry. But the use of the powered hand tools could cause health problems such as cumulative trauma disorders and vibration white fingers. In this study. the effects of hand-arm vibration and anatomical hand position on localized muscle fatigue were analyzed. Eight healthy male subjects volunteered for the study. Vibration frequencies of 0, 40, 80, 100, 150, and 200Hz and hand position of flexion and ulnar deviation were selected for the independent variables of the experiment. Median frequency shifting was used as a dependent variable. The results indicated that at the vibration frequency of 40Hz and accelation of 2g, the muscle fatigue was the greatest. For the hand position. there was significant difference between neutral and flexion. and neutral and ulnar deviation, but no difference between flexion and ulnar deviation. These results could be applied in designing powered hand tools to minimize the health problems.

• The Journal of Korean Physical Therapy
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• v.22 no.4
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• pp.21-28
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• 2010

Purpose: The purpose of this study was to evaluate the electromyographic (EMG) activity of vastus medialis oblique (VMO) and vastus lateralis (VL) muscles on foot position and knee angle for hemiplegia patients. Methods: Ten stroke subjects (10 males) participated in the study. Subjects were all right-hemiplegic patients. All subjects did $0^{\circ},\;20^{\circ}$ and $40^{\circ}$ knee flexion while maintaining the foot in a neutral position, or at $30^{\circ}$ adduction or at $30^{\circ}$ abduction. Surface EMG data were collected for VMO and VL muscles on the non-hemiplegic side and hemiplegic side. Collected data were analyzed using two-way ANOVA. Results: VMO and VL activities for the non-hemiplegic and the hemiplegic sides were highest for $40^{\circ}$ knee flexion while maintaining the three foot positions. There were no significant differences in EMG activity of the VMO and VL muscles with different foot positions. There were significant differences between VMO and VL activity for knee flexion angle while maintaining the foot in neutral (p<0.05), at $30^{\circ}$ adduction (p<0.05), or at $30^{\circ}$ abduction (p<0.05). Conclusion: Foot position does not influence VMO and VL activities. But, knee flexion exercise in a closed chain can increase VMO and VL muscle activity for hemiplegic patients. In particular, VMO and VL activities for both the non-hemi side and the hemi side were highest for $40^{\circ}$ knee flexion.

• The Journal of Korean Physical Therapy
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• v.19 no.2
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• pp.33-39
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• 2007

Purpose: The purpose of this study was to investigate the effect of wrist position on grip strength. A Grip-Strength is measurement of muscle strength in hand. It is evaluated for the motor function and handicap of hand, projection of treatment plan. It is important because correct treatment. Methods: Total 80 college students were participated in this study, who consisted of 40 males and 40 females(age range: $20{\sim}26$). A Grip-Strength Dynamometer was used to measure the grip strength in three wrist position(flexion, extension, neutral position) and two elbow position(supination, pronation). The ANOVA was conducted to determine any significant difference in grip strength between the wrist position and the two elbow position. Results: The results were as follows: 1. The grip strength was affected by wrist position changes. 2. The difference of grip strength according to elbow position Was not significant difference (p>0.01). 3. The grip strength i1l neutral position was strongest among 3 position of wrist (p<0.01). Conclusion: A Grip-Strength was significant difference in wrist position. Pronation position was minimum grip-strength but not significant difference between supination and pronation.

• Physical Therapy Korea
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• v.21 no.2
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• pp.48-56
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• 2014

The aim of this study to investigate the effects of craniocervical flexion on muscle activities of scapular upward rotators during push-up plus exercise in subjects with winging scapula. Eighteen males with scapular winging were recruited, and each subject performed knee push-up plus and other exercises, in two conditions (craniocervical flexion vs. natural head positions). A surface electromyography (EMG) was used to measure upper trapezius (UT), serratus anterior (SA), and lower trapezius (LT) muscle activity. A paired t-test was used to determine the statistical significance between the different condition with/without applying of craniocervical flexion. UT EMG activity significantly decreased and SA EMG activity significantly increased during knee push-up plus involving the craniocervical flexion compared to the natural head position. However, no significant differences (p>.05) were found in the activity of the LT muscle. The UT/SA ratios with and without craniocervical flexion showed a significant difference (p<.05). These results showed that the knee push-up plus other exercises performed with craniocervical flexion could strengthen the serratus anterior muscle and minimize the activity of the UT muscle.

• Journal of Korean Physical Therapy Science
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• v.30 no.3
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• pp.23-30
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• 2023

Background: Flexion of cervical and lumbar joints is required when viewing a smartphone screen. Thus, these joints are overused, together with the surrounding joints and muscles. Long-term use of smartphones will cause changes in cervical and lumbar posture. The effect on forward head posture will vary, depending on the angle of cervical flexion start position in relation to the smartphone. This study investigated how forward head posture changes over time when using a smartphone at 20° and 40° cervical flexion start positions. Design: Cross-sectional study. Methods: Twenty-five subjects with a forward head posture angle of 35° or less participated in the study. A Forward Head Posture app on the participants' smartphones measured forward head posture 5 and 10 minutes after watching videos on their smartphones. Cervical range of motion was used to set a smartphone watching start posture of 20° and 40° of cervical flexion. Results: There was no significant difference in forward head posture, irrespective of cervical flexion start position, but the angle of forward head posture increased more at cervical flexion of 40° than at cervical flexion of 20°. There was no significant difference in what according to smartphone video viewing times, but the angle of forward head posture increased over time. Conclusion: An increase in forward head posture over time with smartphone usage poses a potential risk of neck and shoulder pain. Therefore, smartphone users should avoid prolonged screen time.

• Physical Therapy Korea
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• v.10 no.1
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• pp.63-76
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• 2003

This research was performed to compare spinal segment motion angle between low back pain (LBP) group and painless group during trunk flexion-extension and to investigate the effect of transversus abdominis strengthening exercise on spinal segment motion angle in LBP group. Nine subjects with LBP and ten subjects without LBP participated. Transversus abdominis strengthening exercise was performed in LBP group for three weeks, and spinal segment motion angles were compared before and after the exercise performance. Spinal segment motion angles were measured both in sitting and standing position. Results were as followed: 1) Subjects' average age was 24.79 years, height was 167.84 cm, and weight was 59.95 kg. 2) Spinal segment motion angle of T10/l1 was significantly higher in LBP group compared with painless group (p<.05) in sitting position during trunk flexion-extension. 3) In sitting position, whereas entire lumbar segment motion angles were lower in LBP group compared with painless group (p<.05), angle of L4/5 was higher in LBP group compared with painless group (p<.05). 4) There was no significant difference in thoracic segment motion angle in standing position. 5) After three weeks of transversus abdominis strengthening exercise, thoracic segment motion angle increased both in sitting and standing position (p<.05). 6) In painless group, there was no significant difference in entire spinal segment motion angles in sitting and standing position (p>.05). When spinal segment motion angles were compared between sitting and standing position, there were slight differences. In sitting position, there was no difference in spinal segment motion angle between LBP group and painless group while hip joint motion angle and sacral inclination angle of LBP group was lower than those of painless group (p<.05). In standing position, lumbar segment motion angle was significantly lower in LBP group than that of painless group. Transversus abdominis strengthening exercise influenced thoracic segment motion angle more significantly than lumbar segment motion angle.

• Archives of Reconstructive Microsurgery
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• v.25 no.2
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• pp.43-48
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• 2016

Purpose: Perforator flap-using ischial sore reconstruction is performed in a prone position. But after the surgery, recurrence frequently occurs in a sitting position. In this sense, we introduce modified flap insetting method which closely resembles patient's sitting position to lessen the flap tension surgically. Materials and Methods: Authors tried to check a skin tension difference between prone position and sitting position in normal people group and to find out the importance of performing flap insetting in hip flexion position. Healthy volunteers were collected (n=20) and designed the same length of 4 divided sections around the ischium. Lengths of each section were measured when hip joint was flexed to 90 degree and when both hip and knee joints were flexed to 90 degree and the statistical evaluation was performed. Twenty cases with ischial sore underwent reconstructive surgery using perforator flap under hip flexion position and followed-up for any recurrences. Results: There was a meaningful difference between the joint flexed skin length and that of the neutral position. Flap showed sufficient thickness over 12 months. Conclusion: It seems that recurrence could be reduced when the reconstructed flap could sufficiently cover in a sitting position regarding its significant length difference in normal people group.

• PNF and Movement
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• v.13 no.2
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• pp.95-102
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• 2015

Purpose: The purpose of this study was to analyze the effect of arm flexion patterns of proprioceptive neuromuscular facilitation on muscle activation in the contralateral lower extremity. Open kinematic chain and closed kinematic chain positions were used. Methods: This study used an electromyogram (MP150, Biopac Systems, USA) to measure muscle activation in 20 healthy male students. Comparative analysis was completed on muscle activation of the vastus lateralis, biceps femoris, tibialis anterior, and gastrocnemius of the contralateral lower extremity. Open kinematic chain and closed kinematic chain positions were used with a unilateral arm flexion-abduction-external rotation pattern. Paired t-tests using the SPSS 12.0 for Windows analyzed the data produced by the electromyogram. Results: There was a statistically significant difference in muscle activation in the biceps femoris, gastrocnemius, and tibialis anterior when the open kinematic chain and closed kinematic chain positions were compared (p < 0.05). Conclusion: The biceps femoris, gastrocnemius, and tibialis anterior muscles showed greater muscle activation in the closed kinematic chain position when compared to the open kinematic chain position.

• PNF and Movement
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• v.19 no.1
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• pp.1-8
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• 2021

Purpose: The purpose of this study was to determine how the position of tibial rotation affects peak force and hamstring muscle activation during isometric knee flexion in healthy women. Methods: Seventeen healthy women performed maximum isometric knee flexion at 30˚ with three tibial rotation positions (tibial internal rotation, neutral position, and tibial external rotation). Surface electromyographic (EMG) activity was recorded from the medial hamstring (MH) and lateral hamstring (LH) muscles. The strength of the knee flexor was measured with a load-cell-type strength-measurement sensor. Data were analyzed using one-way repeated analysis of variance. Results: The results showed that MH and LH activities and peak force were significantly different among the three tibial rotation conditions (p < 0.01). The post-hoc comparison revealed that the MH EMG activity in tibial neutral and internal rotation positions were significantly greater than tibial external rotation (p < 0.01). The LH activity in tibial external rotation was significantly greater than the tibial neutral position and internal rotation (p < 0.01). The peak force of the knee flexor was also greater in the external tibial rotation position compared with the tibial neutral and internal rotation positions (p < 0.01). Conclusion: Our findings suggest that hamstring muscle activation could be changed by tibial rotation.

• Physical Therapy Korea
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• v.18 no.1
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• pp.57-63
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• 2011

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.