• Korean Journal of Applied Biomechanics
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• v.33 no.1
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• pp.1-9
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• 2023

Objective: This study identifies the difference among the heights of a chair's backrest (High, Mid, No), the biomechanical changes chair users undergo over time, and the variables that can measure musculoskeletal disorders, eventually providing information on the appropriate type of backrest. Method: Eleven healthy subjects in their 20s and 30s who had no experience with musculoskeletal disorders or surgical operations within the last 6 months participated in this study. Computer typing tasks were randomly designated and performed according to the type of chair backrest, and evaluation was performed for Flexion-Relaxation Ratio (FRR) analysis after the computer typing tasks. This study used eight infrared cameras (sampling rate: 100 Hz) and nine-channel electromyography (sampling rate: 1,000 Hz). ANOVA with repeated measures was conducted to verify the results, with the statistical significance level being α = .05. Results: Although there was no significant difference in craniovertebral angle (CVA), this study showed time and interaction effects depending on the height of the backrest (p<.05). When working without the backrest, the head-spine angle was lower compared to the chairs with backrest, based on the computer work. As for the head angle, the higher the back of the chair was, the less the head flexion and the body angle became, whereas the body flexion became less when there was a backrest. In addition, the body flexion increased over time in all types of backrests (p<.05). The muscle activity of the upper body tended to be high in the high backrest chair. On the other hand, a lower muscle activity was found with a low backrest. Conclusion: These results show that a chair is more ergonomic when the body angle is correctly set without bending and when it is supported by a low backrest. Accordingly, this study determines that the backrest affects shoulder and neck musculoskeletal disorders during typing and that medium-height backrest chairs can help prevent musculoskeletal disorders, contrary to the expectation that high-backrest chairs are preferable.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.22 no.1
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• pp.65-70
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• 2016

Background: To determine the correlation Between forward head posture and plantar pressor in a McKenzie Exercise. Methods: This study had a cross-sectional design. There are included 20 participants with forward head posture. We measured the craniovertebral angle (CVA), cranial rotation angle (CRA) by image obtained digital camera and the plantar pressure, static balance using Gait Analyzer each before and after McKenzie Exercise. Results: There was negative correlation between CVA and CRA (p<.05). There was negative correlation between CVA and fore foot(p<.05). There was positive correlation between CRA and both fore foot (p<.05). There was negative correlation between CVA and static balance(p<.05). There was positive correlation between CRA and static balance (p<.05). Conclusions: There is a correlation between the change a mount of forward head position and plantar pressure in the McKenzie Exercise.

• Journal of The Korean Society of Integrative Medicine
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• v.5 no.3
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• pp.21-28
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• 2017

Purpose: The purpose of this study was to investigate the effects of three exercise programs on forward head posture. Methods: Ninety-five individuals were recruited to assess the of the pectoralis minor muscle. Of these, 36 individuals with pectoralis minor muscles were selected and randomly divided into three groups: a functional massage group, a stretching group, and a stretching and muscle strengthening group. The exercise program consisted of sessions four times per week for two weeks. The length of pectoralis minor and the activity of the trapezius muscles were measured using electromyography. Forward head posture was assessed using the craniovertebral angle (CVA) and the cranial rotation angle (CRA) pre-, during and post-treatment. Result: Significant improvements were observed in pectoralis minor length, CRA, and CVA post-treatment in all groups (p<0.05, p<0.01, p<0.001). However, only the activity of the lower trapezius demonstrated a statistically significant difference post-treatment. There were no significant differences between the groups. Conclusion: The findings of this study suggest that all three exercise programs were effective in improving forward head posture and the length of pectoralis minor post-treatment.

• Osong Public Health and Research Perspectives
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• v.9 no.6
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• pp.309-313
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• 2018

Objectives: The purpose of this study was to determine whether the cranial vertebral angle (CVA) and the range of motion (ROM) was different between participants with a forward head posture (FHP), with or without pain. Methods: Forty-four participants who had FHP participated in this study. The FHP was assessed digitally by measuring a lateral view the CVA for each subject. A cervical ROM device measured the cervical ROM. The volunteers were allocated to either, with pain (n = 22), or without pain (n = 22) groups, and pain was evaluated using the Numeric Pain Rating Scale. Results: The FHP in the pain group showed a significant difference in the CVA, and the cervical ROM in both flexion and extension, compared with those in the FHP without pain group (p < 0.05). Logistic regression analysis indicated that the occurrence of cervical area pain was higher amongst subjects who had a decreased CVA and flexion motion. Conclusion: This study suggested that decreased CVA and cervical flexion range, were predictive factors for the occurrence of pain in the cervical region.

• The Journal of Korean Physical Therapy
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• v.35 no.3
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• pp.83-88
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• 2023

Purpose: This study was to investigate the effect of forward head posture (FHP) and round shoulder posture (RSP) on changes in muscle activities according to shoulder flexion and abduction tasks. Methods: Twenty-two male subjects with no history of neurological, musculoskeletal surgery or injuries, or pain in the spine region within the previous 3-month periods were recruited for this study. Craniovertebral angle (CVA) and Scapula Index were measured before performing 90° abduction and flexion tasks holding a 3kg dumbbell. Muscle activities were measured during the tasks. All measurements except height of the acromion were carried out in a sitting position at the height of the subject's knee angle of 90 degrees, and two tasks were randomly performed with the arm that the subject mainly use to throw the ball. The abduction and flexion angles were checked by the examiner using a goniometer beside the subject. Results: Correlation coefficient analysis between Scapular Index and upper trapezius muscle activity during shoulder abduction task showed significant positive correlation. No significant correlation was observed between CVA, Scapular Index, and other muscle activities. Conclusion: FHP showed increased muscle activation, making it difficult to change muscle activity under lower loads, and RSP was correlated with UT activation in shoulder abduction. Therefore, in the RSP, the loaded shoulder abduction is considered a potential risk factor for increasing shoulder muscle tension. This paper proposes an approach to treating RSP before FHP.

• Physical Therapy Rehabilitation Science
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• v.11 no.4
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• pp.446-453
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• 2022

Objective: The popularization of smartphones can lead to abnormal cervical alignment in university students. The aim of this study was to investigate the relationship among smartphone screen time, cervical alignment, and muscle function in university students. Design: Cross-sectional study. Methods: Seventy-five university students participated in the study. They completed the evaluation of cervical alignment and muscle function, such as handgrip strength, proprioception, and muscle quality (tone, stiffness, and relaxation time). All participants recorded their general characteristics and individual smartphone screen time before the evaluation. They were evaluated craniovertebral angle (CVA) using smartphone application (angle meter 360) for measuring cervical alignment. The muscle function was assessed using a digital hand-held dynamometer, dual inclinometer, and MyotonPRO device. Results: Of all participants, twenty-five university students had forward head posture (CVA<49°, 33.33%). Independent t-test revealed that there were significant differences on smartphone screen time, muscle stiffness, and muscle relaxation between the participants with and without forward head posture (p<0.05). There were significant correlations between the smartphone screen time and the CVA, muscle tone, and muscle relaxation (r=-0.493, 0.250, and -0.500, respectively). Conclusions: The results indicate that the university students with forward head posture had high smartphone screen time and muscle stiffness compared to the students without forward head posture, and smartphone screen time might be associated with cervical alignment and muscle quality.

• Physical Therapy Rehabilitation Science
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• v.10 no.3
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• pp.251-256
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• 2021

Objective: The forward head posture (FHP) is strongly related to the rounded shoulder posture (RSP), which is associated with shoulder pain. Design: Observational cross sectional study design Methods: A total of 37 were enrolled in the study, 22 individuals with FHP(experimental group) and 15 healthy adults(control group). Correlation with differences between groups was analysed through craniovertebral angle (CVA) representing FHP for both groups, neck disability index (NDI) indicating neck pain, disability of the arm, shoulder and hand (DASH) indicating shoulder pain. Results: There was a significant difference in the results of CVA, NDI, and DASH in FHP and healthy adults (p<0.05). Significant correlations were found between DASH and CVA in FHP participants (r = -0.656, p = 0.001). Also, in the regression analysis results of DASH and CVA, the regression model was found to be suitable and the variation in DASH could be explained by 43% (F = 15.118, p = 0.001). Conclusions: Shoulder pain and neck discomfort are potentially related, and an increase in shoulder pain can increase FHP.

• Journal of International Academy of Physical Therapy Research
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• v.10 no.2
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• pp.1763-1767
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• 2019

Background: Although previous researches have developed interventions for neck problems, headache, and temporomandibular disorder in patients with forward head posture (FHP), changes in masticatory muscle tone or stiffness as FHP worsening have not been investigated. Objective: To examine changes in masticatory muscle tone and stiffness through craniovertebral angle (CVA). Design: Cross sectional study Methods: The subjects were 21 healthy males with normal head posture. Three CVA were established for posture measurement in which the bilateral anterior temporal and masseter muscles were measured during the subjects maintained a series of postures. Results: The Right masseter muscle significantly increased in stiffness with advancing FHP (p < 0.05). No significant changes were observed in the muscle tone or stiffness of any other masticatory muscles, and no significant differences were found in bilateral masticatory muscle tone or stiffness in each measurement posture. Conclusions: This study suggests that the increased stiffness of the right masseter muscle as the FHP worsened requires consideration in physical therapy assessment and intervention.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.3
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• pp.291-296
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• 2021

This study examined the effects of the forward head posture on the maximum mouth opening of the jaw joint and the muscle activity and asymmetry of the temporalis and masseter. The craniovertebral angle was measured in 50 subjects (23.10±2.73 years) who met the selection requirements of the study. The maximum mouth opening, muscle activity, and muscle asymmetry were measured by reducing 0%, 10%, and 20%. As the craniovertebral angle decreased, the maximum mouth opening decreased (p<.001), the muscle activity of the right and left temporalis decreased (p<.001), and the muscle activity of the left temporalis also decreased. (p<.01). The asymmetry rate of the added muscles of the left and right temporalis, left and right temporalis, and masseter increased according to the change in condition (p<.01). The results of this study are expected to help establish a treatment strategy and comprehensive diagnosis for the temporomandibular joint and present a theoretical basis of manual therapy and therapeutic exercises used for the treatment of TMD.

• Journal of the Korean Society of Physical Medicine
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• v.17 no.4
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• pp.1-13
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• 2022

PURPOSE: This study examined the effects of the craniovertebral angle, proprioception (joint error test), and the upper trapezius on the muscle tone when comparing cervical stabilization and scapula stabilization exercises and when two exercises were performed together. METHODS: The participants in this study agreed in advance, and this study was carried out by recruiting 27 university students in their twenties with mild frontal posture. The subjects were assigned randomly to three groups that performed cervical stabilization exercises, scapular stabilization exercises, and both cervical and scapular stabilization exercises. One-way repeated ANOVA was used to analyze the evaluation values of the 1^st, 3^rd, and 6^th weeks of exercise intervention within the group, and one-way ANOVA was used to compare the difference in the effects of exercise intervention among the three groups. RESULTS: Proprioception was significantly different in the cervical stabilization exercises (CSE) group and the cervical stabilization exercises + Scapular stabilization exercises (CSE+SSE) groups at three weeks, and there was a significant difference between the scapular stabilization exercises (SSE) group and the CSE+SSE group (p < .05). At six weeks, there was a significant difference between the CSE group and the CSE+SSE group, and there was a significant difference between the SSE group and the CSE+SSE group (p < .05). There was a significant difference between three and six weeks in the CSE group (p < .05). In the SSE group, there was a significant difference between pre and six weeks, and between three and six weeks (p < .05). In the CSE+SSE group, there was a significant difference between pre and three weeks, and between pre and six weeks (p < .05). On the other hand, there were no significant differences between CVA and muscular tone in all three groups (P > .05). CONCLUSION: In all groups, the proprioception (joint error test) showed significant improvement, and the CSE+SSE group showed greater improvement than the other groups. As a result, the appropriate combination of neck stabilization exercise and scapular stabilization exercise effectively improved proprioception in the presence of forward head posture (FHP).