Abstract
BackgroundWe examined the effectiveness of a manual therapy consisting of forearm skin rolling, muscle mobilization, and upper extremity traction as a preventive treatment for rats performing an intensive lever-pulling task. We hypothesized that this treatment would reduce task-induced neuromuscular and tendon inflammation, fibrosis, and sensorimotor declines.MethodsSprague-Dawley rats performed a reaching and lever pulling task for a food reward, 2 h/day, 3 days/week, for 12 weeks, while simultaneously receiving the manual therapy treatment 3 times per week for 12 weeks to either the task-involved upper extremities (TASK-Tx), or the lower extremities as an active control group (TASK-Ac). Results were compared to similarly treated control rats (C-Tx and C-Ac).ResultsMedian nerves and forearm flexor muscles and tendons of TASK-Ac rats showed higher numbers of inflammatory CD68+ and fibrogenic CD206+ macrophages, particularly in epineurium, endomysium and epitendons than TASK-Tx rats. CD68+ and CD206+ macrophages numbers in TASK-Tx rats were comparable to the non-task control groups. TASK-Ac rats had more extraneural fibrosis in median nerves, pro-collagen type I levels and immunoexpression in flexor digitorum muscles, and fibrogenic changes in flexor digitorum epitendons, than TASK-Tx rats (which showed comparable responses as control groups). TASK-Ac rats showed cold temperature, lower reflexive grip strength, and task avoidance, responses not seen in TASK-Tx rats (which showed comparable responses as the control groups).ConclusionsManual therapy of forelimbs involved in performing the reaching and grasping task prevented the development of inflammatory and fibrogenic changes in forearm nerves, muscle, and tendons, and sensorimotor declines.
Highlights
Musculoskeletal disorders secondary to occupational overuse are highly prevalent in many professions [1,2,3]
We extended our past 12 week study to determine if this combination of manual therapy treatments could: 1) prevent or reduce inflammatory Inflammatory type macrophages (M1) type macrophage (CD68+) numbers in nerves, muscles and tendons; 2) increase Interleukin 10 (IL-10) levels; 3) improve sensory hypersensitivity, since we did not examine such changes in our past 12 week manual therapy treatment study [13]; and 4) examine for the first time, the effects of a massage/manual therapy treatment on fibrogenic Fibrogenic type macrophages (M2a) type macrophages
No significant differences between the four groups were observed in the mean number of calls (Table 1 and Supplemental Fig. 2)
Summary
Musculoskeletal disorders secondary to occupational overuse are highly prevalent in many professions [1,2,3]. Prolonged performance of a high repetition high force lever-pulling task induces sensorimotor declines and neuromuscular inflammation (increased numbers of pro-inflammatory macrophages and cytokines) and fibrosis [7, 9,10,11,12,13,14,15], yet effective preventive treatments that can be provided long-term are still needed (i.e., concurrent with the continued “work”). We examined the effectiveness of a manual therapy consisting of forearm skin rolling, muscle mobilization, and upper extremity traction as a preventive treatment for rats performing an intensive lever-pulling task. We hypothesized that this treatment would reduce task-induced neuromuscular and tendon inflammation, fibrosis, and sensorimotor declines
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