Increasing muscle extensibility


This is the first of three articles I read on the plane yesterday. I have two patients with knee flexion contractures (one ambulatory, one not), so this was of significant interest to me. What is happening when a stretch is applied? Apparently it is not a mechanical change in tissue but likely in a change in the participants sensation. Much more research is needed and this provided more questions than answers for me, but it was thought provoking and provided a good discussion with my wife.


Holzman Weppler C, Magnusson SP. Increasing Muscle Extensibility: A Matter of Increasing Length or Modifying Sensation? Phys Ther 2010; 90:438-449.

Various theories have been proposed to explain increases in muscle extensibility observed after intermittent stretching. Most of these theories advocate a mechanical increase in length of the stretched muscle. More recently, a sensory theory has been proposed suggesting instead that increases in muscle extensibility are due to a modification of sensation only. Studies that evaluated the biomechanical effect of stretching showed that muscle length does increase during stretch application due to the viscoelastic properties of muscle. However, this length increase is transient, its magnitude and duration being dependent upon the duration and type of stretching applied. Most of these studies suggest that increases in muscle extensibility observed after a single stretching session and after short-term (3- to 8-week) stretching programs are due to modified sensation. The biomechanical effects of long-term (>8 weeks) and chronic stretching programs have not yet been evaluated. The purposes of this article are to review each of these proposed theories and to discuss the implications for research and clinical practice.

Photo credit:Stretch, originally uploaded by hey mr glen


3 responses to “Increasing muscle extensibility

  1. Cynthia Weppler

    Dear Dr. Gillette,
    Thank you for including the Increasing Muscle Extensibility perspective article I wrote with Dr. Magnusson on your Blog. I appreciate your comments about the article. While performing research for this paper, I was surprised to find how little basic research has been performed regarding this topic – especially since it is so fundamental to rehabilitation, sports training and general fitness. I found that there are a number of theories regarding muscle extensibility and stretching that are widely accepted as conventional wisdom that are not supported by experimental evidence. So I am very happy with your comments that more research is needed and that the article provided more questions than answers. I think this topic has been over-simplified in much of rehabilitation literature and that a more sophisticated concept of muscle length is required in order to understand current research and in order to pose more valuable research questions.
    I also wanted to let you and your readers know that we did post a Clarification to one paragraph of the Perspective that appears in the April PTJ. This was, in part, a response to a question posed by a reader regarding contract/relax stretching. The question and reply appear as a Rapid Response on the PTJ web site and will be printed as a Letter to the Editor in the June PTJ.
    Thank you for your interest.
    Cynthia Weppler

  2. Cynthia Weppler

    P.S. The link to the Rapid Response is

    • Thanks for the comments and the link to the Rapid Response Cynthia. I hope you or someone else out there has a study planned or in the works to dig into this further!

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