Task characteristics and lower back disorders.
In 1995, Kim and Chung measured fatigue arising from repetitive manual materials handling (MMH) tasks. They found more pronounced fatigue in asymmetric versus symmetric postures during task performance. Also, they found that muscles become fatigued more quickly during light load-high frequency tasks such as those performed at the Animal Care Facility than for heavy load-low frequency tasks. Related to this, Allread, Marras and Parnianpour (1996), reported that one-handed lifting results in back motion characteristics previously associated with lower back disorders (LDB). The weights used in this study also correspond well with those encountered at the Animal Care Facility, for instance 7.5 lbs (3.4 kg, about the weight of the shelter boxes in the pens) and 15 lbs (6.8 kg, about the weight of the an adult woodchuck and stovepipe shelter). In the breeding facility, asymmetric lifting occurs at least 100 times each day per worker. According to the research findings, one-handed lifting tasks such as, lifting woodchucks and their shelters and scooping feed from the barrels, increase the risk that employees will suffer from increased fatigue and lower back disorders. Allread, et al. also reported that in previous studies, manual materials handling was found to be the dominant factor in occupationally related LBD.
Allread, G.W.; Marras, W.S.; and Parnianpour, M. (1996). Trunk kinematics of one-handed lifting, and the effects of asymmetry and load weight. Ergonomics, 39(2), 322-334.
Kim, S.H., and Chung, M.K. (1995). Effects of posture, weight, and frequency on trunk muscular activity and fatigue during repetitive lifting tasks. Ergonomics, 38(5), 853-863.
Last modified May 14, 1997