[Purpose] This study aims to improve the safety for caregivers and avoid musculoskeletal diseases by examining the shoulder and trunk muscle activity depending on wheelchair handle height as the caregiver provides propulsion to a wheelchair for wheelchair-bound patients. [Subjects] The participants were caregivers who met the criteria for this study (n=30). [Methods] To determine the activity of the shoulder and trunk muscles of caregivers depending on the handle height, the muscle activity was measured as a wheelchair was being pushed under three height conditions. [Results] According to the study results, the deltoid middle fiber, serratus anterior muscle, rhomboid muscle, and erector spinalis of lumbar part showed significantly low muscle activity at a height that produced an elbow joint flexion angle of 30°. Caregivers are highly likely to develop musculoskeletal disease if the handle height is excessively low. In addition, the burden on the shoulder and back muscles can be reduced at heights that lead to flexion of 30°. [Conclusions] As a caregiver pushes a wheelchair, the handle height has a close relationship with the burden on the shoulder and back muscles. If the handle height is excessively low, the caregiver is highly likely to develop musculoskeletal disease.

Abstract.[Purpose] The purpose of this study was to suggest the proper seat height for wheelchair propulsion on a slope.[Subjects] Participants who met the criteria for this study (n=20).[Methods] Muscular activity was measured while propelling the wheelchair using the chairs of heights corresponding to elbow flexion angles of 0, 30, 60 and 90 degrees. To eliminate the effect of muscular fatigue that might have been caused, wheelchair propulsion with the four elbow joint angles was randomly performed. EMG electrodes to the attached were pectoralis major, flex carpi radialis, extensor carpi radialis, serratus anterior, anterior deltoid, biceps brachi, triceps and lattisimus dorsi.[Results] The anterior deltoid, pectoralis major, triceps, extensor carpi radialis and flexor carpi radialis muscle activations showed significant differences between each groups. [Conclusion] This study investigated propulsion on a slope, not flat ground, where propulsion force is offset by potential energy. Thus, unlike flat ground, where small muscle activity is sufficient for propulsion, much muscle activation is necessary to stably go up a ramp.Our results show that in climbing a ramp, user stability is likely to be compromised at wheelchair seat heights eliciting elbow flexion of less/greater than 60 degrees.

[Purpose] This study verified the leg muscle activities of elderly subjects performing leg cycle ergometer exercise. [Subjects] Forty-one elderly persons were the subjects of this study. [Methods] For the three distances corresponding to knee flexion angles of 15, 45, and 70, the muscle activities of the rectus femoris, biceps femoris, tibialis anterior and lateral gastrocnemius were measured while the subjects exercised on a cycle ergometer. [Results] The rectus femoris and biceps femoris showed statistically significant increases as the distance between the cycle ergometer and the body increased, and the lateral gastrocnemius muscle activation showed a statistically significant increase as the distance from the body to the cycle ergometer decreased. [Conclusion] When the elderly have limb muscle weakness, leg cycle ergometer distances should be adjusted.

[Purpose] The aim of this study was to develop a new handle holder by modifying the inclination of the existing handle holder to reduce load on the wrist joints. [Subjects and Methods] The subjects of this study consisted of 25 elderly people aged 65 years or older accustomed to a walker-assisted gait. Two types of handle holders ((1) standard handle holder (2) inclination handle holder) were applied to all subjects and their wrist joint movement and muscle activity were measured while they conducted 10 cycle walker-assisted gait. [Results] The use of an inclination handle holder during the walker-assisted gait decreased considerably the extensor carpi radialis longus activity and angles of the ulnar deviation and wrist extension. [Conclusion] Improvements in the overall structure of a walker may be a new tool for improving existing walker users but the replacement cost will be expensive. The inclination handle holder presented in this study decreases the burden on the wrist joints of walker users without any overall structural changes in the walker, thereby reducing the occurrence of musculoskeletal diseases of the wrist joint during the walker-assisted gait of elderly people.