Brazilian Journal of Physical Therapy
On-line version ISSN 1809-9246
KAROLCZAK, Ana P. B.; DIEFENTHAELER, Fernando; GEREMIA, Jeam M. and VAZ, Marco A.. Two-weeks of elbow immobilization affects torque production but does not change muscle activation. Rev. bras. fisioter. [online]. 2009, vol.13, n.5, pp. 412-421. Epub Sep 11, 2009. ISSN 1809-9246. http://dx.doi.org/10.1590/S1413-35552009005000050.
BACKGROUND: Limb immobilization has been extensively used during the recovery process of musculoskeletal injuries despite the fact that this technique causes functional deficits in the skeletal muscle. There is evidence showing strength reduction due to muscle hypotrophy and an increase in the percentage of fast-twitch fibers, however it is still unclear how the injuries and the immobilization contribute to these changes. OBJECTIVE: To verify the influence of elbow joint immobilization on the torque-angle relationship and on electrical activation of the elbow flexor and extensor muscles in healthy subjects. METHODS: Eighteen male subjects (22 to 42 years) were assigned to either a control group (n=11) or to an immobilization group (n=7). All subjects performed the same tests twice with a 14-day interval period. The immobilization group had the non-dominant elbow joint immobilized with a cast at a joint angle of 90º during 14 days. Maximal isometric torques were obtained with the elbow joint positioned at 150º, 120º, 90º and 60º. RESULTS: There was a 16% reduction in maximal torque after immobilization that cannot be explained by changes in arm girth or by reduction in the electrical activation of the muscles. CONCLUSIONS: Fourteen days of immobilization produced a reduction in maximal elbow isometric torque but did not change muscle activation in healthy subjects. This reduction in maximal torque production seems to be related to muscle hypotrophy and is probably less pronounced when compared to that from immobilization after musculoskeletal injuries.
Keywords : immobilization; electromyography; torque; elbow joint.