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Netball & Injuries again

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  • Netball & Injuries again

    I tried to post a message yesterday, and for some unknown reason only half
    the message made it to the list. Here is the full posting, and thanks to
    those of you that have replied so far.

    As part of an undergraduate sports biomechanics project, I am investigating
    injury potential in netball.

    The rules of netball require players to halt suddenly as soon as they receive
    the ball. This means that ground reaction forces on landing after catching
    the ball are relatively high compared to other activities. Netball has a
    high injury rate (when compared with basketball, for example), with most
    injuries occurring at the ankle and knee. Our experiment has attempted to
    evaluate the injury potential for two conditions: catching a ball aimed at
    chest level, and catching a ball aimed 2.5 m high. In both cases, the
    subject landed on a force plate and took no more than one and a half steps
    after landing. Ground reaction forces were plotted against time. Approach
    speed was controlled.

    Steele and Milburn (1988a) found that on landing after high passes compared
    with chest level passes there was: a lower magnitude of initial peak vertical
    ground reaction force (VGRF), greater attenuation of peak VGRF, and lower
    horizontal braking forces. They recommended the promotion of a high passing
    game style to reduce injuries. In their 1989 study, Steele & Milburn
    suggested that this greater dampening of landing forces after high passes was
    because subjects tended to land on their forefoot, allowing an additional
    body segment to play an active role in force attenuation. Neal and
    Sydney-Smith (1992) pointed out that approach speed was not controlled in
    Steele and Milburn's work. They concluded that the modulating effect of a
    high pass is related to lower approach speeds, and suggested that jumping to
    catch a high pass may negate the attenuating effects of a forefoot landing on
    peak VGRF

    [Steele, J.R., Milburn, P.D. Reducing the risk of injury in netball:
    changing rules or changing techniques? NZ journal of health physical
    education and recreation 21 (1): 17-21. Steele, J.R., Milburn, P.D. A
    Kinetic Analysis of Footfall Patterns at Landing in Netball. Australian
    Journal of Science and Medicine in Sport. 21 No.1 March 1989. Neal RJ,
    Sydney Smith M The effects of footfall pattern and passing height on ground
    reaction forces in netball. Australian Journal of Science and Medicine in
    Sport. September 1992.]

    Does anyone know of any studies pertaining to any jumping sports which have
    controlled horizontal speed experimentally prior to landing? Have any
    studies linked horizontal braking forces on decelerating from a run with
    injury potential? I have already searched medline and sport discus with few

    In addition, I am interested to know why the magnitude of the initial peak
    VGRF (which is a transient peak superimposed on the rising phase of the VGRF
    time trace) on landing in netball or in any jumping sport is related to
    injury potential. I have heard that this represents force experienced
    before the musculoskeletal system has had a chance to react to impact, but I
    have no references. The magnitude of this initial force is typically lower
    than peak VGRF. Are greater stresses experienced during this initial peak
    than when VGRF has reached maximum? Is this because the musculoskeletal
    system has not yet aligned properly at this point?

    Why is it assumed that GRF magnitudes, loading rates etc. are correlated with
    injury potential, which is surely determined by a multitude of factors?

    Any ideas or references would be gratefully accepted, and I will post a
    summary of replies.

    David Egan

    Sports Studies Undergraduate, Brunel University College