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Spastic CP: can we go slow-to-fast. Summary of responses

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  • Spastic CP: can we go slow-to-fast. Summary of responses

    Thanks to all who made contributions. Along with the original query, they
    are listed below.
    Original query:
    Dear Subscribers,
    There have been two articles in the literature (Rose et al., J. Orth. Res.
    12 758-68 and Ito et al., Brain and Development 18: 299-303) suggesting that
    there is a predominance of type-I fibres in gastrocnemius muscle of children
    with spastic cerebral palsy, possibly due to the altererd patterns of
    stimulation that these muscles receive. Because of the slower dynamic
    qualities of these muscles it is possible that they exacerbate the poor
    motor abilities that these children possess.
    It has been suggested to me that transformation of type-I to type II fibres
    may occur with high intensity exercise or high intensity electrical
    stimulation. It makes soem sense, but does anybody know of reported data to
    support this view?
    I'd be grateful for any help.

    Adam Shortland PhD
    One Small Step Gait Laboratory

    Take a look at:

    Skeletal muscle adaptation to chronic low-frequency motor nerve stimulation.
    AUTHORS: Kraus WE, Torgan CE, Taylor DA
    SOURCE: Exerc Sport Sci Rev. 1994;22:313-60. Review

    It is an excellent review and should get you going.

    James C. Martin
    Assistant Professor
    Department of Exercise and Sport Science
    University of Utah
    Check Astrand and Rodahl Textbook of work physiology. I'm not sure, but it
    may be there.
    Beverly Burke RN CMA CIE
    I know of no evidence to support the inference that ES will assist in a
    transfer of Type I to Type II.

    The evidence would suggest that long term training may slow muscle
    characteristics down (suggesting a response to the stimulus which
    parallels the suggested Type II - I change). The possible reason for this
    is that during submaximal stimulation the fast twitch fibres tend to be
    activated. (loosely following the principle of reverse recruitment order),
    with long-term low grade activations the metabolic charactertistic of the
    muscle tend to be more endurance orientated. - hence a "shift to slow".

    other points for consideration.

    1. I'm not sure of the reason why High intensity would tend to speed up the
    fibre twitches - There is a suggestion that the recruitment of fibre type
    is reversed with ES. Increasing the intensity would just target more Slow
    twitch fibres.

    2. Using frequency to modulate the "intensity" may have a slightly
    different effect by altering when certain fibres contract tetanically -
    obviously this has an upper limit and increased frequency may increase the
    chance of "cramp" and / or frequency dependent fatigue. ("calcium washout"
    I think is partially the mechanism?). This type of ES would not be
    considered 'functiona;" and would probably mean to target a specific
    neurological response or to strengthen the muscle.

    3. the relative responses of muscle in a training situation are relative to
    the stimulus it receives in the process of normal activity. For example in
    individuals with SCI the decreased activation of muscles with an UMNL is
    relatively low and 8 hours a day of ES represents a signficiant training
    stimulus resulting in a relatively large training response. Therefore, one
    would have to be concerned as to the relative training stimulus an ES
    program would have on a child with CP who is functionally active (or may
    have a high level of tone even at rest) and has normal sensation and
    compliance :-).

    4. The differences in the rate of torque production of the gastrocnemius in
    a "predominantly slow twitch" vs. a gastrocnemius with a "predominantly
    fast twitch" is clinically insignficiant in the functional outcome of gait.
    In the circumstance where there is a limitation to the ability to
    co-ordinate agonists and antagonists during a ballistic action (or some
    degree of velocity sensitivity to muscle length changes - spastcity) then
    the rate of force production as determined by twicth fibre type in my
    opinion can not be clinically significant for an activity like walking.

    5. The sensory impact of high intensity ES in CP child may have more effect
    on the central mechanisms than the peripheral (muscle fibres). For example,
    synergies of the motor patterns for gait may be altered. In some
    circunstances it may improve the gait by creating muscle fatigue in a
    muscle which is inapprorpiately active, it may facilitate voluntary
    activation of the muscle or it's synergists or indeed it may create a
    inhibitory effect of the antagonistic that may or may not be a problem.

    In summary, I'm not sure the predominance of fibre type in the gastroc. has
    a significant impact on the function of CP gait over and above the central
    motor control dysfunction. The fibre type is probably a reflection of the
    stimulus the muscle receives. ES may have an impact but not for the reason
    of muscle fibre transformations.

    Just my opinion and 2 cents worth.

    Garry T Allison (A/Professor of Physiotherapy)
    The Centre for Musculoskeletal Studies
    Department of Surgery, The University of Western Australia.

    Dear Dr. Shortland,
    I received you query second hand, thus the delay. I imagine you have had
    a wealth of response. I seem to recall one paper, probably back in the
    1970's, that reported changing muscle fibers from slow to fast. The paper
    was never substantiated, and I don't recall the authors, so they probably
    didn't publish a lot more, further casting doubt on their work. Most of
    the literature on fiber type conversion (true conversion for one class to
    the other) says that ES as it is conventionally used shifts fibers toward
    being slow. The little bit of human work and most of the animal work
    definately demonstrates the shift from fast to slow when adequate levels of
    stimulation are used.
    The one other thought I had is that Dr. Daniel Kernell had some
    preliminary work attempting to maintain muscle power during prolonged
    inactivity. He was using a hybrid stimulation program of high intensity,
    short duration (presumibly challinging the largest, fastest fibers) along
    with the more common long duration stimulation. I don't recall that he did
    any fiber typing. The paper I reference for this was in J Neurophys
    58:598-613, 1987. I looked for anything more recent about a year ago, but
    I haven't checked for anything in the last several months.
    It is my understanding that voluntary exercise, no matter the intensiy,
    really doesn't cause fiber type shift from slow or fast. There are changes
    within the fast fiber type, but no clear cut shift to slow. I have seen
    nothing that would indicate slow fibers shifting to fast ones under
    voluntary exercise conditions.

    Lucinda L. Baker PT PhD
    Department Biokinesiology & Physical Therapy
    University of Southern California

    In response to your query, there is a review article from 1991 (Roy, Baldwin
    and Edgerton, 1991. The plasticity of skeletal muscle: Effects of
    neuromuscular activity, Exercise and Sport Sciences Reviews, 19, 269-312)
    which goes into detail as to myosin heavy chain changes found in various
    animals e.g. cats and rats, when subjected to various protocols, from
    suspended limb inactivity to neuromuscular electrical stimulation.

    There is also a recent article that goes towards fibre type changes after a
    period of bed rest, although these changes were only found at the gene
    level, not at the protein level. Therefore it could be proposed that a
    longer period of bed rest may elicit more demonstratable changes from type 1
    to type 2 fibres.

    A study that has demonstrated the changes in fibre types is:
    {PRIVATE}Andersen and Aagaard (2000). ,Myosin heavy chain IIX overshoot in
    human skeletal muscle. Muscle Nerve; 23(7):1095- 104. Apparently JL Andersen
    from the muscle research group in Copenhagen has done a fair amount of work
    in this area, so I guess that he's your man.

    I hope that these little suggestions are of assistance.

    Chris Swann,
    MSc Sport and Exercise Science (Biomechanics),
    School of Sport Science,
    University College Chichester,
    College Lane,
    West Sussex PO19 4PE,
    United King dom.

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