Abstract
ObjectivesTo describe the effects of immobilization, free remobilization and remobilization by physical exercise about mechanical properties of skeletal muscle of rats of two age groups.Methods56 Wistar rats divided into two groups according to age, an adult group (five months) and an older group (15 months). These groups were subdivided in: control, immobilized, free remobilized and remobilized by physical exercise. The pelvic limb of rats was immobilized for seven days. The exercise protocol consisted of five swimming sessions, once per day and 25 minutes per session. The gastrocnemius muscle was subjected to tensile tests, and evaluated the properties: load at the maximum limit, stretching at the maximum limit and stiffness.ResultsThe immobilization reduced the values of load at the maximum limit and the remobilization protocols were not sufficient to restore control levels in adult group and older rats. The stretching at the maximum limit differs only in the older group.ConclusionsThe immobilization reduces the muscle's ability to bear loads and exercise protocol tends to restore the default at control values in adult and older rats. The age factor only interfered in the stretching at the maximum limit, inducing a reduction of this property in the post-immobilization. Level of Evidence II, Investigating the Results of Treatment.
Highlights
The immobilization of a body segment is a procedure generally used for the treatment of musculoskeletal injuries, it can result in undesirable structural alterations[1] such as muscle atrophy,[2] change in the number of sarcomeres in series,[2] reduction in the glycogen reserve,[3] increase of connective tissue, diminished strength[2,3] and muscle weight.[4]
Immobilization reduced the load at the maximum limit (LML) values both in the adult and in the older animals (Tables 1 and 2)
It can be noted that the protocol of remobilization by physical exercise shows a tendency to increase the value of this property, this was not sufficient to restore LML at control levels
Summary
The immobilization of a body segment is a procedure generally used for the treatment of musculoskeletal injuries, it can result in undesirable structural alterations[1] such as muscle atrophy,[2] change in the number of sarcomeres in series,[2] reduction in the glycogen reserve,[3] increase of connective tissue, diminished strength[2,3] and muscle weight.[4] Previous studies showed alterations after two or three weeks of immobilization,[3,4] yet there are studies that show that some of these adaptations can already be observed in less than seven days.[2,5] Williams et al.[6] declare that starting from six hours of immobilization, it is possible to observe loss of proteins. Many fibers are reinnervated by other motor neurons, this process is insufficient to totally compensate for alterations caused by the denervation, resulting in the atrophy of muscle fibers.[12]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
