Gluteus Medius MMT: Was Kendall Wrong?
If you are familiar with Florence Kendall's method of Manual Muscle Testing (MMT), you are likely aware of the fact that she prefers to test muscle strength in a partially shortened position. When muscle length is in mid-range, it allows optimal cross-bridge linking, leading to a higher potential for force production. When muscles are over-extended or excessively shortened, the muscles lose that high frequency of cross-bridge linking. If you look at Kendall's MMT for the gluteus medius, you might see that she tries to emphasize the posterior fibers by having the patient on the side with the pelvis tilted forward and hip in extension, abduction, and lateral rotation. This is position completely shortens the muscle, thus potentially lower the validity of strength assessment. We have already discussed the use of evaluating hip abduction strength in a closed-chain position. Something else to consider is the fact that the gluteus medius is essential for pelvic stability throughout the entire stance phase of the gait cycle, not just mid-stance (where Kendall tests). Does it really matter if you have a level pelvis at midstance if you cannot keep your pelvis stable at heel strike? We have been presented another method for testing the gluteus medius in open-chain. Instead, place the lower extremity in hip abduction, lateral rotation, and flexion. The examiner then applies a flexion and adduction directed force. This position allows the muscle to not be completely shortened and tested in a functionally useful position. The position of flexion that is added can mimic heel strike in the gait cycle, making certain the muscle is strong enough to prevent pelvic drop as soon as stance begins.
11/12/2013 07:53:57 am
Do we not worry about over activation of the Tensor Fascia Latae by playing the leg into flexion? Are we no longer suppose to take into consideration the strength fight between Gluteus Medius and TFL?
The TFL's action is flexion, abduction, and medial rotation. By placing the lower extremity into lateral rotation and applying a force as the examiner in a flexion and adduction direction, TFL activation is minimal. I recommend having someone perform this method on you to get a better feeling for it. You will likely note greater strain posteriorly instead of anterior like you feel with TFL activation!
11/23/2013 10:50:47 pm
You make a really good point. I think it is important to test the LE in different positions that mimic motion, but it is important to know what fibers you are testing.
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