• 한국운동역학회지
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• 제29권4호
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• pp.255-261
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• 2019

Objective: The purpose of this study was to investigate differences of shock attenuation strategies between double-leg and single-leg landing on sagittal plane using statistical parametric mapping. Method: Nine healthy female professional soccer players (age: 24.0±2.5 yrs, height: 164.9±3.3 cm, weight: 55.7±6.6 kg, career: 11.2±1.4 yrs) were participated in this study. The subjects performed 10 times of double-leg and single-leg landing from the box of 30 cm height onto force plates respectively. The ground reaction force, angle, moment, angular velocity, and power of the ankle, knee, and hip joint on sagittal plane was calculated from initial contact to maximum knee flexion during landing phase. Statistical parametric mapping was used to compare the biomechanical variables of double-leg and single-leg landing of the dominant leg throughout the landing phase. Each mean difference of variables was analyzed using a paired t-test and alpha level was set to 0.05. Results: For the biomechanical variables, significantly increased vertical ground reaction force, plantarflexion moment of the ankle joint, negative ankle joint power and extension moment of the hip joint were found in single-leg landing compared to double-leg landing (p<.05). In addition, the flexion angle and angular velocity of the knee and hip joint in double-leg landing were observed significantly greater than single-leg landing, respectively (p<.05). Conclusion: These findings suggested that negative joint power and plantarflexion moment of the ankle joint can contribute to shock absorption during single-leg landing and may be the factors for preventing the musculoskeletal injuries of the lower extremity by an external force.

• Physical Therapy Rehabilitation Science
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• 제6권1호
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• pp.33-38
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• 2017

Objective: This study tried to examine the muscle activity of the neck and trunk according to head posture changes during use of laptops. Design: Cross-sectional study. Methods: This study included nineteen young men and women. All subjects maintained each posture while practice typing on laptops for ten minutes with a 5-minute break between each posture. For the neutral head posture, the subjects practiced typing while pulling their chins down towards the Adam's apple and were able to look at their knees while having their external auditory meatus, acromion, and greater trochanter vertical to the ground. For the natural head posture, they practiced typing while balancing their posture between extension and flexion of the cervical vertebrae by themselves without any guidelines. While a forward head posture was created by having their heads face the front horizontal to the rope hanging from the ceiling, they practiced typing with their external auditory meatus located in the place which was 5 cm in front of the vertical plane. The subjects used general word process but practiced typing with accuracy and high speed. Muscle activities were randomly measured using surface electromyography according to each postures. Results: The research result had found that muscle activity with the natural head posture was more significantly reduced than that of the forward head posture in the sternocleidomastoid muscle, upper trapezius, cervical vertebral spinae, and thoracic vertebrae spinae muscles (p<0.05) and that the neutral head posture was more significantly reduced than that of forward head posture in the upper trapezius, cervical vertebral spinae, and thoracic vertebrae spinae muscle activity (p<0.05) with significant increases in lumbar spinae muscle activity (p<0.05). Also, muscle activity with the neutral head posture significantly increased more in the sternocleidomastoid muscle and lumbar spinae than that of the natural posture (p<0.05). Conclusions: Our study results suggest that in order to prevent musculoskeletal pain, the neutral head posture with use of laptops is effective in reducing load to the shoulders and vitalizing the postural muscles.

• 한국전문물리치료학회지
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• 제26권2호
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• pp.61-68
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• 2019

Background: Forward head posture (FHP) is a postural alignment of the cervical vertebrae that leads to increased gravitational load on cervical segmental motions. The overhead arm lift test assesses the ability to actively dissociate and control low cervical flexion and move the shoulders through overhead flexion. Objects: The purpose of this study was to explore muscle activities in the upper trapezius (UT), serratus anterior (SA), sternocleidomastoid (SCM), and lower trapezius (LT) alongside changes in head position during the overhead arm lift test in individuals with FHP. Methods: Fifteen subjects with forward head posture and fifteen subjects with normal subjcects were enrolled in this study. The patients performed the overhead arm lift test, and muscle activities of the UT, SCM, SA, and LT were measured using surface electromyography and by evaluating changes in head position. Independent t-tests were used to detect significant differences between the two groups and Cohen's d was calculated to measure the size of the mean difference between the groups. Results: The FHP group demonstrated significantly increased muscle activity of the UT ($32.46{\pm}7.64$), SCM ($12.79{\pm}4.01$), and LT ($45.65{\pm}10.52$) and significantly decreased activity in the SA ($26.65{\pm}6.15$) than the normal group. The change in head position was significantly higher in the FHP group ($6.66{\pm}2.08$) than the normal group. Effect sizes for all parameters assessed were large between the two groups. Conclusion: The subjects with excessive FHP displayed were unable to fix their heads in position during the overhead arm lift test. The overhead arm lift test can thus be used in clinical settings to confirm control of the neck in these subjects.

• PNF and Movement
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• 제18권3호
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• pp.415-424
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• 2020

Purpose: This study aimed to compare changes in abdominal muscle thickness in different standing postures with a handheld load between subjects with and without chronic low back pain (CLBP). Methods: Twenty subjects with CLBP and 20 controls participated in this study. Ultrasound imaging was used to assess the changes in the thickness of the transverse abdominis (TrA), internal oblique (IO), and external oblique (EO) muscles. Muscle thickness in three different standing postures (standing at rest, standing with loads, standing with lifting loads) was compared with the muscle thickness at rest in the supine position and was expressed as a percentage of change in the thickness of the muscle. Results: While standing with loads, the change in IO muscle thickness in the CLBP patients increased more significantly than in the pain-free controls (p < 0.05). The standing with lifting loads posture showed a significant increase in the change in thickness of the TrA compared with the standing with loads posture (p < 0.05). In addition, the standing with lifting loads posture showed a significant decrease in the change in the thickness of the EO when compared with the standing with loads posture (p < 0.05). Conclusion: The automatic activity of the IO muscle in subjects with CLBP increased more than that of the pain-free controls in the standing with loads posture. These findings suggest that IO muscle function may be altered in those with CLBP while standing with loads. Additionally, TrA the activation level was found to be associated with increased postural demand caused by an elevated center of mass.

• Journal of Yeungnam Medical Science
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• 제6권2호
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• pp.223-239
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• 1989

요추의 중립위, 굴곡위 및 신전위에서의 응력 분포의 차이와 수핵의 유무에 따른 응력 분포의 변화를 관찰하기 위해 본 연구를 시행하였으며 등색선의 양상을 관찰하고 그 응력을 해석하여 다음과 같은 결론을 얻었다. 1. 기립 중립위에서는 수핵이 있는 경우는 전방 부위보다 후방부위에 고응력이 집중되었으며, 전후방 모두 내측부와 중간부위가 고응력이고 외측부로 이동할수록 저응력이 관찰되었다. 수핵이 없는 경우는 후방보다 전방부에 고응력이 집중되었으며 국소적으로 응력이 집중되는 양상을 보이고 있다. 2. 최대 굴곡위에서는 수핵의 존재에 관계없이, 전방보다 후방부가 고응력이 집중되었으며, 수핵 유무 비교시 수핵이 있는 경우가 없는 경우보다 전방이 저응력, 후방은 거의 동등한 응력 분포를 나타내었다. 응력 분포도의 분석에 의하면 전반적으로 균등한 응력 분포 양상을 나타냈다. 3. 최대 신전위에서는 수핵 유무에 관계없이 전방부에 고응력, 후방부에 저응력, 내측에 고응력, 외측은 저응력을 나타내었으며, 수핵이 있는 경우 없는 경우보다 고응력을 나타냈다. 4. 기립 중립위와 최대 굴곡위의 비교에서는 기립 중립위보다 굴곡시 수핵의 유무에 관계없이 전반적으로 후방부 응력이 2차 정도 현저히 감소하는 양상을 보이면서 비교적 균등한 응력 분포를 나타냈다. 5. 최대 신전위와 최대 굴곡위의 비교에스는 수핵 존재시 최대 신전위보다 최대 굴곡위에서 응력 분포가 전후방 모두 2차 정도 감소되고 수핵이 없는 경우는 최대 신전위가 굴곡위보다 응력이 전후방 0.5차 정도 감소되었다.

• 한국심리학회지 : 문화 및 사회문제
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• 제9권spc호
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• pp.107-122
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• 2003

본 논문에서는 근골격계질환, 특히 직업성요통에 관련되는 위험요인의 영향을 종합적으로 살펴보고자 하였다. 첫째로 물리적인 요인의 영향을 알아보기 위하여 해석적인 인체역학 모델과 NIOSH(National Institute for Occupational Safety & Health) Guidelines를 이용하여 자동차 조립작업의 직업성 요통관련 위험도를 평가하였다. 총 246 작업자에 대한 분석을 수행하였는데, 분석결과 총 20개의 작업에서 L5/S1에서의 압축력이 300kg이 넘었으며 44개의 작업은 NIOSH Guidelines에 의한 분석결과, 최저허용기준치(ACTION LIMIT)을 넘는 것으로 나타났다. 둘째로 사회심리적 요인과 직업성요통의 관계에 대해 분석하였다. 사회심리적 요인의 영향을 알아보기 위하여 증상과 PWI(Psychosocial Well-being Index)를 토대로 한 설문을 이용하여 246명 작업자 모두에게 설문조사를 실시하였다. 그 결과 207명의 작업자가 직업성 요통증상을 경험한 적이 있으며 특히 27명의 작업자는 유병자로 분류된 바 있는 사람들이었다. PWI 점수를 근거로 하여 나눈 두 집단(저스트레스군, 고 스트레스군)은 증상이나 진단결과에 있어서 통계적으로 유의한 차이를 보이지 않았다. 또한 사회심리적 스트레스와 작업강도와의 관계를 살펴보면 주로 작업자세요인과 사회심리적 스트레스가 유의한 관계를 가지는 것으로 나타났다. 마지막으로 직업성요통의 발생에 대하여 경로분석을 수행하였다. 분석결과 인구학적 요인, 사회심리적 요인, 작업특성 요인이 직업성 요통에 직접적으로 영향을 미쳤으며, 개인특성요인 즉, 작업경험, 흡연, 수면시간 등은 직업성요통에 직접적인 영향을 미치는 않은 것으로 나타났다. 그러나 개인특성요인은 직업성 요통에 유의한 영향을 미치는 사회심리적 요인과는 밀접한 관계를 가졌다. 향후 다양한 직종에서의 이와같은 경험적 연구결과가 축적되어 우리나라의 조직문화적 특성을 고려한 직업성 요통에 대한 위험모델에 구축되어야 한다고 사료된다.