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Serum and tissue cytokines and chemokines increase with repetitive upper extremity tasks.
Barbe-MF; Elliott-MB; Abdelmagid-SM; Amin-M; Popoff-SN; Safadi-FF; Barr-AE
J Orthop Res 2008 Oct; 26(1):1320-1326
This study investigated changes in motor skills and tissues of the upper extremity (UE) with regard to injury and inflammatory reactions resulting from performance of a voluntary forelimb repetitive reaching and grasping task in rats. Rats reached for food at a rate of 4 reaches/min, 2 h/day, and 3 days/week for up to 8 weeks during which reach rate, task duration and movement strategies were observed. UE tissues were collected bilaterally at weekly time points of 3-8 weeks and examined for morphological changes. Serum was tested for levels of interleukin-1alpha (IL-1) protein. The macrophage-specific antibody, ED1, was used to identify infiltrating macrophages and the ED2 antibody was used to identify resident macrophages. Rats were unable to maintain baseline reach rate in weeks 5 and 6 of task performance. Alternative patterns of movement emerged. Fraying of tendon fibrils was observed after 6 weeks in the mid-forelimb. After 4 weeks, a general elevation of ED1-IR macrophages were seen in all tissues examined bilaterally including the contralateral, uninvolved forelimb and hindlimbs. Significantly more resident macrophages were seen at 6 and 8 weeks in the reach limb. At 8 weeks, serum levels of IL-1alpha increased significantly above week 0. Our results demonstrate that performance of repetitive tasks elicits motor decrements, signs of injury and a cellular and tissue responses associated with inflammation.
Laboratory-animals; Animals; Animal-studies; Injuries; Repetitive-work; Cellular-reactions; Cumulative-trauma; Cumulative-trauma-disorders; Ergonomics
Mary F. Barbe, Department of Physical Therapy, College of Health Professions, Temple University, 3307 North Broad Streeet, Philadelphia, PA 19140
Issue of Publication
Journal of Orthopaedic Research
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division