View Full Version : Avoidance of extremes of joint motion (summary)

Cathy Dean
10-24-1995, 02:53 AM
>I am posting a summary of the responses I got to my request listed below.
Thanks to all
>those who responded. If anyone has other comments to make I would be very
interested and happy to compile a summary for the list.
>Original request
>If the elbow were completely extended, then the muscle groups
>responsible for flexion of the arm would be almost completely
>useless or incapacitated by that position. The reason is that
>they would not be able to produce a moment or torque at the
>elbow due to the mechanical configuration. This being the
>case, the elbow would then depend solely on it's ligaments
>for support. Here I believe is where the body becomes a bit
>smarter than we normally percieve it to be. It doesn't like
>to trust us with loading those ligament, instead it prefers to
>play it safe and keep a little kink in the elbow so as to
>aviod ligament dependancy and increase the mechanical
>advantage of the flexural muscle groups.
>I hope this comment helps out some, good luck.
> Charles A. Garris III.
>__________________________________________________ ________
> The ergonomics literature has many references to 'avoiding extremes of
>joint motion'. you're not clear about what you request : '..origin/reference
>for 3)...'. What do you mean exactly? what do you want?
>There are many god biomechanical reasons for avoiding extremes of joint
>A simple biomechanical analysis based on first principles will show this.
>Ross Armstrong
>Lecturer in ergonomics
>Manager, Centre for Ergonomics and Human Factors
>La Trobe University
>Locked Bag 12, Carlton Sth P.O., Victoria 3053
>tel +61 3 9285 5311 fax +61 3 9285 5184
>email hubrga@lure.latrobe.edu.au
>__________________________________________________ ____
>Your statement pertaining to avoiding extremems of joint movement
>was very interesting and I would appreciate learning of any
>additional data you have that supports this idea. Presumably, you
>are aware that joint receptors have traditionally been considered
>as functioning to prevent joint from overextending or flexing by
>becoming very active at the extremes of movement. However, more
>recent data suggest that muscle action resulting from such receptor
>activity would be too slow to prevent joint damage in most cases. I
>would be happy to provide you with references if you want them.
>Joel Vilensky
>Indiana University, Fort Wayne
>G.J. Van Ingen Schenau and his colleagues have been working on lower limb
>(human) and hind limb (quadruped) biomechanics during cyclic and ballistic
>movements. One proposal by the group is that full extension of the "leg"
>is not achieved during jumping because such a position approaches the
>limits of the musculoskeletal systems, in terms of power or torque
>They have experimented with a model suggesting that full extension takes
>the limb into an orientation where the torque generating power of muscles
>becomes negligible. Since the purpose of muscles is to cause joint
>rotations (torques) which in turn lead to body translations, efficient
>utilization of muscle power occurs prior to full extension.
>Therefore, they reason that the full extension position is undesirable
>when applying loads to or resisting loads from the external environment.
>Perhaps info from their studies might help in your research. You might
>want to search for recent (since 1990) work from van Ingen Schenau with
>coworkers like Jacobsen and Bobbert.
>John H. Lawrence III, Ph.D.
>Center for Biomedical Engineering
>University of Kentucky
>Lexington, KY 40506-0070
>Firstly, the observation must be made that even if the person did
>extend their elbow to 100%, the object would still be out of reach.
>I guess it is a bit like reaching for a tennis ball in a swimming
>pool. If it is "just" out of reach, we can somehow "learn" to
>stretch that "little" bit further, but if it is too far away (140%)
>we simply give up.
>We may be prepared to compromise our intrinsic balance constraints
>if we convince ourself that it is worth it, and have time to devise a
>safe compromise strategy. How we know what our "intrinsic reach" is
>perhaps learnt from experience, but there must also be structural
>warning mechanisms in our neuroanatomy. I must confess ignorance
>as to what these may be.
> Craig Nevin
> Biomedical Engineer
> Department of Physiology/Sports Science
> University of Cape Town, South Africa
> CNEVIN@anat.uct.ac.za
>__________________________________________________ __
>Do these subjects "fully extend" their elbows when asked to?
>The other (more helpful) thought that came to me was that perhaps
>the other kinematic accommodations made are adequate to get the
>hand in the general proximity of the target, but the elbow joint
>maintains a little reserve to make corrections, etc. that may be
>necessary due to normal performance variability / accuracy issues.
>:: Philip Schot, PhD ::
>:: Department of Human Kinetics ::
>:: University of Wisconsin-Milwuakee ::
>:: Milwaukee, WI 53201 ::
>:: USA ::
>:: EMAIL- pschot@csd.uwm.edu ::
>:: PHONE- 414-229-6080 (dept.) ::
>:: 414-229-6899 (lab) ::
>:: FAX- 414-229-5100 ::
>__________________________________________________ ________
>Saw your inquiry on the network. You may want to look up the
>work of David A.Rosenbaum et al "Constraints for action selection:
>Overhand vs underhand grips". In Attention and Performance XIII edited by
>Jeannerod in 1990. Rosenbaum has published more recent work in this area
>which would pop up through a medline computer search.
>Ann Gentile
>I was most interested to read your posting regarding the idea of avoidance of
>the extreme range of joint motion. I hope this information will be of help to
>I am familiar with the concept as it was theorized by a pianist and teacher I
>worked with who had developed a new concept of virtuoso piano technique (how's
>that for coming from left field!) Her name is Dorothy Taubman. In a nutshell,
>Taubman's model derived from the idea of coordinated movement of all the
>concerned technical elements, e.g., finger, hand, forearm, upper arm. When
>these elements move within their limits, i.e., mid-range of motion, etc.,
and in
>the right timing and amount, then labor is evenly divided between all the
>technical elements, the subjective experience of strain and effort disappears
>and extraodinary changes take place in the technical abilities of the pianist.
>I am simplifying drastically, but I hope you'll get the idea.
>I personally witnessed incredible transformations in pianists who underwent
>retraining, and I experienced it myself working with one of Taubman's teaching
>assistants. It sounds a bit like snake oil, but the stuff is truly a bit of
>Her approach also poses a new idea for prevention and rehabilitation of
>injuries, which Taubman has been able to do with pianists with unprecedented
>success over the last 40 years. Taubman theorizes that overuse syndrome in
>pianists is really misuse, arising from incorrect training and a lack of
>understanding of the mechanical limits of the piano. Central to her theory is
>the idea that any movement that requires the 'limbs'
(fingers/hands/forearms) to
>move beyond the mid-range of motion leaves the executant open to strain, misuse
>and injury. Traditional training methods promote exactly this kind of movement
>at the piano, and that is why the rate of injury is so high among musicians;
>some studies put the incidence as high as 75% among professionals.
>A few years ago, I adapted the piano technique to the computer keyboard and
>been presenting it to injured computer operators in California for the last two
>years with some very promising results. If you would be interested, I
>a paper at ErgoCon '95 last May that explains the theory in more detail. I
>be happy to send you a copy via snail mail. Also, I would be very
interested in
>the responses you get. I am not at all conversant in the research and will be
>extremely interested to see what you come up with.
>Greg Dempster
>Director, Triangle Associates
>POB 59
>Laguna Beach, CA 92652-0059, USA
>Tel/Fax 714/497-1715
>re: avoiding extremes of joint range. You may be able to discuss your
>finding in relation to some of these models:
>Cruse H Bruwer M and Dean J 1993 JMB 25,3,131-139. tested a mathematical
>model of motor control which supported the assumption that joint movement
>be equally distributed among available joints..
>Hirayama et al in JMB 25,3,162-174 described a model based on a minimal
>torque criterion;
> Uno Y Suzuki R Kawato M 1989 Minimum muscle tension change model which
>reproduces human arm movement Proceedings of the Fourth Symposium on
>Biological and Physical Engineering Fukuoka Japan, 299-302 ( I don't have a
>copy of this one)
>__________________________________________________ _____________________
>Trisha Bate | email : P.Bate@LaTrobe.edu.au
>School of Physiotherapy | Phone : 03 285 5259
>Faculty of Health Sciences | or : 03 481 1718
>La Trobe University | Fax : 03 285 5225
>___________________________________|______________ _______________________
>The idea of avoiding extremes of joint angles was directly
>investigated in a series of studies by Cruse and Bruwer:
>Bruwer, M. & Cruse, H. (1990) A network model for the control of
>the movement of a redundant manipulator. Biol. Cyber., 62, 549-555.
>Cruse (1986) Constraints for joint angle control of the human
>arm. Biol. Cyber. 54, 125-132.
>Cruse, Bruwer, & Dean (1993) Control of three- and four-joint
>arm movement: strategies for a manipulator with redundant degrees
>of freedom. J. of MOtor Behavior, 25, 131-139.
>Also, Rosenbaum's Knowledge Model uses the same idea within a more
>complex model, and he is usually good about referring back to
>original sources.
>Rosenbaum, E.A., Engelbrecht, S.E., Bushe, M. & Loukopoulos, L.D.
>(1993). Knowledge model for lselecting and producing reaching
>movements. J. of Motor Behavior, 25(3).
>Rosenbaum, D.A., Loukopoulos, Meulenbroek, Vaughan & Engelbrecht
>(1995) Planning reaches by evaluating store postures. Psych.
>Review, 102, 28-67.
>And, recently Kelso has been talking about recruiting extra degrees
>of freedom when the state space becomes limited by exactly the kind
>of situations you're talking about. I haven't followed his written
>work lately to know where he discusses that, but you probably can
>track that lead down easily enough.
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>Rebecca A. States, Ph.D. 276H Read Building
>Dept. of Health & Kinesiology (409) 862-3229
>Texas A & M University (409) 847-8987 (fax)
>College Station, Texas 77843-4243 states@tam2000.tamu.edu
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