• The Journal of Korean Physical Therapy
• /
• v.18 no.6
• /
• pp.67-75
• /
• 2006

Purpose: Many kinds of musculoskeletal disease and symptom are caused by the longtime computer works. However, trapezius muscle tonus has not been established in regarding to keyboard height during typing. Therefore, this study is to evaluate the relationship between trapezius muscle tonus and the height of keyboard while typing, controling for the postures of neck, Lumbar, cervical vertebra. Methods: The experimental height of keyboard was set at elbow height, 3cm higher, 6cm higher, 9cm higher, than elbow. We studied trapezius tonus with the mean value for 2 minutes by EMG in 15 males and 15 females worker of hospital in seoul, who did not have a history of muscle disease, neurological signs, nerve damage. Results: In this experimental, as the height of the keyboard went up, the trapezius tonus significantly increased with shoulder abduction of brachium. Second, right and left trapezius tonus appeared similar while typing. Third, the best height that release the trapezius tonus the was as high as elbow and 3cm higher than elbow. Conclusion: With these above results, we suggest that the appropriate height of keyboard during typing to release the trapezius tonus most is the height of the elbow and 3cm higher than elbow. The study has important implications for focusing on the height of VDT worktable and complaining of a pain by oneself which are useful to establish a method of prevention of musculoskeletal disorder in work in the future.

• Korean Journal of Applied Biomechanics
• /
• v.26 no.1
• /
• pp.71-82
• /
• 2016

Objective: The purpose of this study was to investigate kinematic comparisons of Tsukahara vault in gymnastics between a top-level athlete and sublevel collegiate athletes in order to obtain information on key biomechanical points for successful Tsukahara vaults. Methods: An Olympic gold medalist (height, 160 cm; weight, 52 kg; age, 25 years) and five sublevel collegiate gymnasts (height, $168.2{\pm}3.4cm$; weight, $59.6{\pm}3.1kg$; age, $23.2{\pm}1.6years$) participated in this study. They repeatedly performed Tsukahara vaults including one somersault. Fourteen motion-capturing cameras were used to collect the trajectories of 26 body markers during Tsukahara vaults. Event time, displacement and velocity of the center of mass, joint angles, the distance between the two hands on the horse, and averaged horizontal and vertical impact forces were calculated and compared. Results: The top-level athlete showed a larger range of motion (ROM) of the hip and knee joints compared to sublevel collegiate athletes during board contact. During horse contact, the top-level athlete had a narrow distance between the two hands with extended elbows and shoulders in order to produce a strong blocking force from the horse with a shorter contact time. At the moment of horse take-off, reactive hip extension of the top-level athlete enhanced propulsive take-off velocity and hip posture during post-flight phase. Conclusion: Even though a high velocity of the center of mass is important, the posture and interactive action during horse contact is crucial to post-flight performance and the advanced performance of Tsukahara vaults.