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The Relationship of Anticipatory Gluteus Medius Activity to Pelvic and Knee Stability in the Transition to Single-Leg Stance

Kim, D., Unger, J., Lanovaz, J. L., & Oates, A. R. (2016). The Relationship of anticipatory gluteus medius activity to pelvic and knee stability in the transition to single-leg stance. PM&R, 8(2), 138-144.

Double to single leg transition, which occurs frequently in our daily lives, hugely challenges the stability of our pelvis. Failure to control pelvic posture in this event can cause a cascade effect on hip and knee stability. Gluteus Medius is a hip abductor muscle known to provide stability to the pelvis during the transition to single leg stance. This study shows that proactive activation of Gluteus Medius controls both pelvic and knee stability even before the onset of single leg transition. Especially, the cumulative magnitude of activation of this muscle right before the transition (over the time period covering from 60msec prior to the onset of single leg transition to the onset of single leg transition), not the earlier timing per se, was related to the stability of pelvis and knee. This begs another important question: How do our central nervous system develop the precise timing for such proactive activation of Gluteus Medius and successfully counter destabilizing forces around pelvis and knee at the right moment?

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Overcoming the Myth of Proprioceptive Training

Kim, D., Van Ryssegem, G., & Hong, J. (2011). Overcoming the myth of proprioceptive training. Clinical Kinesiology: Journal of the American Kinesiotherapy Association, 65(1), 18-29.

As proprioceptive exercise became popular in the field of athletic training, important two questions were raised: 1) Can proprioception be trained by exercise? 2) Is proprioceptive training useful for preventing athletic injuries and improving balance? This paper provides a review of literature regarding such questions. In conclusion, improvement of proprioception is feasible only by learning of central nervous system rather than adaptation of peripheral sensory receptors. In addition, prevention of injuries and improvement of reactive balance require an improvement of brain's ability to predict sensory consequences and precisely pre-plan the motor command. Therefore, it is recommended that fitness trainers focus on providing various sensory environments for maximizing proprioceptive learning of their clients.


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Hamstring to quadriceps strength ratio and noncontact leg injuries: A prospective study during one season

Kim, D., & Hong, J. (2011). Hamstring to quadriceps strength ratio and noncontact leg injuries: A prospective study during one season. Isokinetics and Exercise Science, 19(1), 1-6.

It has been consistently suggested that relatively weaker hamstring compared to quadriceps contributes to non-contact athletic knee injuries. In this study, it was observed that lower hamstring to quadriceps strength ratio was related to overall non-contact hip and ankle injuries rather than the knee injuries. One possible mechanism for this result is that athletes with deficient hamstring strength modified a behavior of ankle or hip joint to compensate for the instability of their knee during high impact jump landing situation. This result may support a growing idea that linked multiple joints compensate each other to dissipate the mechanical stress on the lower body. However, this study does not provide a direct evidence for such a theory.

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