Dose-response relationship between reach repetition and indicators of inflammation and movement dysfunction in a rat model of work-related musculoskeletal disorder.
Barbe-M; Safadi-F; Popoff-S; Barr-A
Temple Univ J Orthop Surg Sports Med 2007 Mar; 2:67-71
We have developed an in vivo rat model of work related musculoskeletal disorders of the upper extremity in order to determine the extent to which repetitive tasks cause motor decrements and inflammation in musculoskeletal tissues and systemically. This study compares the effects of high and low reach rates on serum and tissue inflammatory responses and on reach performance. Forty-seven rats reached repetitively for 2 hours/day, 3 days/week for 3-8 weeks at a high or low rate. Forelimb musculotendinous tissues were examined for macrophage infiltration, and proteins indicative of inflammation and injury (COX2 and hsp 72). Reach rate and abnormal movement patterns were recorded. Serum was assayed for IL-1 alpha and IL-1 beta. Tissue inflammation was evident by week 3 in the high repetition rats, and peaked in week 6. High repetition animals also experienced a 2-fold decline in reach rate, and strong emergence of a raking movement. Serum IL-1 alpha, but not IL-1 beta, increased in the high repetition group, but decreased in the low repetition group. This model provides evidence that both local and systemic inflammation and motor decrements increase with high repetition, responses that are attenuated at the lower rate. These findings support the use of risk reduction in WMSD prevention.
Musculoskeletal-system; Musculoskeletal-system-disorders; Workers; Animals; Laboratory-animals; Repetitive-work; Force; Models; Exposure-levels; Tissue-culture; Injuries; Psychological-factors; Behavior; Nerve-damage; Nerve-tissue
Temple University Journal of Orthopaedic Surgery & Sports Medicine
Temple University, Philadelphia, Pennsylvania