At 20:19 31/03/99 +1000, you wrote:
>>>In my opinion, this conception of selective "strengthening" of VMO is
>>conceptually flawed. In patients with PFJ pain syndrome, it is not the
>>strength, but activation pattern of the VMO/VL that is at fault. If the VMO
>>is not being activated early enough during weightbearing flexion then the
>>VL (larger xs area) will cause lateral maltracking. Standard rehab for this
>>in Australia is to retrain selective timing/activation of VMO by using dual
>>channel biofeedback in functional, weightbearing positions (eg lunge, 1/4
>>squat, stepdowns), progressing to in-place plyometrics. Patellofemoral
>>taping (a la McConnell) is vital if maltracking of glide or tilt variety is
>>present.
>>
>>I cannot see how "strength" of the different components of the quads could
>>be measured in isolation. Rather, EMG can be measured, which as we know
>>does not measure force or torque but amount and timing of central
>>activation of the muscle
>>
>>
>However, in practical clinical applications for a great number of clients,
>this seems to be a moot point. It is important for the clinician to know
>what in physiological terms is being achieved. Most of my clients seem to
>require a more straightforward explanation.
>
I respectfully disagree. Telling patients to "strengthen" their VMO usually
results in them piling on weights, increasing resistance and doing things
like leg extensions in inner range. Explaining the poor activation pattern
between VMO and VL is easy, I tell them the motor is out of tune and they
need to fire VMO earlier to balance strong VL. Using dual channel
biofeedback displays this graphically for them. Unless they change the
pattern of activation, gross strengthening ex's will reinforce the existing
faulty activation pattern
In addition, duration of treatment (usually less than four weeks in my
patients) is insufficient time to produce changes in muscle mass and
strength. Studies showing "strength"changes with short durations (ie 6
weeks or less) are actually detecting changes in recruitment and central
drive. Food for thought for a number of rehabilitation protocols
Matt
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