What's Your Vector, Victor?

Sometimes things just don't make sense. Take for example the common scenario of knee pain secondary to patellar tendonitis or perhaps "patella-femoral syndrome". I have seen a number of referrals with the instructions "strengthen the quads" or "push strength" along with " 6 sessions only". After thinking about that, I have a few questions:

How do I strengthen a muscle if the effort produces joint or tendon pain? To produce muscular strength, don't I have to take the muscle to the point of exhaustion? And if the effort is painful, am I truly taxing the muscle or am I stressing something else?

Assuming I can produce muscular exhaustion, how long does it take to produce muscular strength?

What is muscular strength?

Does it matter to my muscles whether I gain that strength in any particular manner? In other words, are my muscles a non-discriminating group? Are they an equal opportunity functional employer?

These are things that keep me up at night.

Muscles are highly discriminating. Ask my muscles to do one thing and I will learn how to do it really well like cycling. But, ask for a run in a 10k race after spending my training time cycling and I'll be lucky to finish 2k of it. Even though the muscles I used in the cycling are exactly the same muscles in running, the training effect of cycling has little transference to running. I am what I do.

The challenge is to change physical function not from "strength" but from neuromuscular learning. The good news is that practically anyone can do it. To better understand this, I conducted a small experiment a few years ago. I asked a student (a great resource for experimentation by the way) to serve as a subject for my study of the quadriceps mystery. I attached surface EMG electrodes to the right quadriceps. I then asked my student to perform a maximum, volitional isometric contraction of the quadriceps to produce a baseline EMG reading. I used this to later reference electrical activity during other tasks.

Next, I instructed my student to step up and down a 9 inch step while I recorded the EMG activity. I discovered that to step up and down the step, my student used about 50% of her maximum volitional capacity. She had therefore a considerable amount of "reserve" capacity if she needed it. I then recorded EMG activity during the following exercises:

Quad sets - EMG activity was 20% of maximum

Straight Leg Raises - EMG activity was 25% of maximum

Full arc open chain knee extension with 10 lbs resistance - EMG activity was 38% of maximum

Stepping up a step with a 5lb force pulling to the right applied at the waist - EMG activity was 80% of maximum

I discovered when I applied a second line of force, a vector, the EMG activity was much higher than any of the other tasks. When I tried this with patients, I found many of them with "anterior knee pain" were initially unable to step up and down a 9 inch step. But if I applied the second line of force, the step became pain-free. I was then able to "push strength" but do so in a functional and pain-free manner. I had found a way to take advantage of the body's inherent learning ability and accelerate it. This technique has worked literally hundreds of times in my clinic as well as others around the country.

The next time you see a patient with "anterior knee pain", try adding a second vector. What do you have to lose? You might just surprise your client and yourself.

Make Today Count.

Doug Kelsey
Author. Teacher. Therapist.