Women’s muscles may require longer, more intensive rehabilitation after bedrest and cast immobilization. This was the conclusion of preliminary data from my laboratory that has recently been accepted as a ‘Brief Report’ for publication in the journal Archives of Physical Medicine and Rehabilitation.

The above assertion is based on our findings from a recent cast immobilization study whereby one-week after removing a cast, women’s muscle strength remained depressed 30-percent below their pre-casting levels while men’s muscle strength virtually returned to baseline. In this experiment, we took five men and five women and cast immobilized their forearm, wrist and hand for three weeks.

Because the study experimentally applied the cast – the subjects were not being immobilized due to fracture, but rather strictly for experimentation – we were able to obtain measures of wrist flexion muscle strength prior to casting, once per week during the casting period, and one week after removing the cast.



Our results indicated that women and men lost strength during casting at a relatively proportional rate with both sexes displaying a 30-percent decrement in strength after three weeks of casting. Interestingly though, when we tested the subjects one week after removing the cast, the men’s strength had returned bask to pre-casting levels, whereas the women’s strength had shown no improvement.

From a clinical perspective these results are very interesting and could have significant implications toward rehabilitation medicine. Especially when one considers that women are four times more likely than men to experience forearm fractures requiring cast immobilization, and almost 50 percent of women will experience a bone fracture at some point in their life, according to data from a 2003 report from the World Health Organization.  

This study did not investigate the question of what causes this phenomenon. There are numerous potential explanations, ranging from differences in neurological adaptations following the recovery from immobilization, to differences in sex-specific hormone regulating the growth of muscle mass – for example, in animals, estrogen is well-known to inhibit protein synthesis – to potential differences in the amount of activity the subjects performed following the cast removal.



Additionally, this study had a fairly small sample size, and we are currently in the process of performing follow-up experiments to try and replicate these results. However, a similar finding had been reported in one other study, with respect to a slower recovery of strength in women compared to men following ACL reconstruction despite both groups undergoing physical therapy.

Accordingly, these findings suggest that sex-specific rehabilitation protocols may be warranted – with women requiring additional or more intensive rehabilitation programs following periods of disuse. However, additional work is needed to determine the extent and mechanisms of these differences.

    — Brian Clark, PhD, is an assistant professor of physiology in the Department of Biomedical Sciences at Ohio University and is the director of the Institute for Neuromusculoskeletal Research. This work was done in collaboration with Richard L. Hoffman, MS, and David W. Russ, PhD, PT of Ohio University, as well as Todd M. Manini, PhD, of the University of Florida. Questions and comments can be directed to editorial@therapytimes.com.