Biomechanics of leaning forward against a support with an extreme standing reach.
Back discomfort, lower extremity loading and unbalanced positions may inhibit workers from standing for industrial stationary work. Two forward-leaning supports were compared to unsupported standing during an extreme reach with 30° trunk flexion under varied light load conditions in the outstretched hands. A total of 11 males from the university participated (mean age 30 years [SD =  5]). Link segment modelling showed a 25-30% reduction in the L4/L5 bilateral hip external moments when using a chest-height support. Ribcage expansion with maximal inspiration remained unchanged with an average 85 N of compression force, and low back discomfort remained tolerable for this difficult reach. Leaning against a work table had no influence on L4/L5 moments or back discomfort because contact was at the pelvis; the external moment at the hips decreased by 6%. Postural stability was improved with little migration of the centre of pressure under both supports. Only the chest support showed potential to influence work positioning and prevent back injuries; further study is needed on support forces and usability.
a School of Occupational and Public health , Ryerson University , Toronto , Canada.
Mohammad
M
Abdoli-Eramaki
Caroline
C
Damecour
Ahmad
A
Ghasempoor
D000328:Adult; D001132:Arm / Q000502:physiology; D001416:Back Pain / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control; D001696:Biomechanical Phenomena / Q000502:physiology*; D064368:Healthy Volunteers; D006615:Hip / Q000502:physiology; D006801:Humans; D008297:Male; D011187:Posture / Q000502:physiology*; D011482:Protective Devices; D013647:Task Performance and Analysis; D013909:Thorax / Q000502:physiology; D060726:Torso / Q000502:physiology; D016474:Weight-Bearing
biomechanics; equipment design; health-care ergonomics; industrial ergonomics; product design