Authors: John Z Wu Sharon S Chiou Christopher S Pan
Publish Date: 2009/03/19
Volume: 37, Issue: 6, Pages: 1177-1189
Abstract
Construction workers often use stilts to raise them to a higher level above ground to perform many tasks such as taping and sanding on the ceiling or upper half of a wall Some epidemiological studies indicated that the use of stilts may place workers at increased risk for knee injuries or may increase the likelihood of trips and falls In the present study we developed an inverse dynamic model of stilts walking to investigate the effects of this activity on the joint moments and musculoskeletal loadings in the lower limbs The stiltswalk model was developed using the commercial musculoskeletal simulation software AnyBody version 30 Anybody Technology Aalborg Denmark Simulations were performed using data collected from tests of four subjects All subjects walked without or with stilts through a 12m straight path The moments of the knee hip and ankle joints as well as forces in major muscles or muscle groups in the lower limbs for stilts walking were compared with those for normal walking Our simulations showed that the use of stilts may potentially increase the peak joint moment in knee extension by approximately 20 induce 15 reduction and slight reduction in the peak joint moments in ankle plantar flexion and hip extension respectively The model predictions on the muscle forces indicated that the use of stilts may potentially increase loadings in five of eight major muscle groups in the lower extremities The most remarkable was the force in rectus femoris muscle which was found to potentially increase by up to 179 times for the stilts walking compared to that for the normal walking The proposed model would be useful for the engineers in their efforts to improve the stilts design to reduce musculoskeletal loadings and fall riskWe would like to thank Dr Frank Buczek National Institute for Occupational Safety and Health for his suggestions on the interpretation of the results and Drs John Rasmussen and Soeren Toerholm Anybody Technology Denmark for the technical supportsTest setup to determine the mass moment of inertia of stilt around y and zaxis The stilt with a mass of M was hung up via a thing string to a fixed point O At t = 0 the stilt was held at a small angle θ from the plumb line and it was then released to swing freely in the xyplane The mass moment of inertia around zaxis I CZ was determined in the tests by counting the swing frequency The mass moment of inertia around yaxis I CY was determined by a swing test in the xzplane
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