December, 2012

How sEMG Helped a Cross Country High School Runner

December 14, 2012

We have learned that looks can be deceiving.  Athletes are great compensators, or cheaters.  They may look like they are performing a perfect movement, but they might be using the wrong muscles at the wrong time which can eventually lead to injury by pushing the muscles tolerance to stress over it's threshold.   Innersport can now fish out the cheaters.

What is sEMG?

Surface Electromyography (SEMG) is a measurement of the muscle’s electrical activity from the surface of the skin and displayed in the form of a graph (line graph or bar graph.) We use sEMG in two ways.  One, to identify which muscles are firing too much or not enough during a particular movement whether it be running, biking, golf, squats, neck movements, etc.  Secondly, once we identify the area that is overfiring or underfiring, we have the patient perform exercises while watching his/her sEMG graphs and videos live as a very effective biofeedback tool. To learn more about sEMG, click here.

How EMG has Helped a High School Cross Country Runner

This summer, a high school cross country runner presented to our clinic with bilateral hip pain (R>L) from running.  Biomechanical exam findings are as follows:

Squat Test-  Difficulty breaking 90 degrees, arms foward, lumbar hyperextension, L>R knee valgus, and bilateral feet turn out.

Step Down- Bilateral Trendelenberg, L>R knee valgus, left lateral hip sway.

Range of Motion-  decreased bilateral ankle dorsiflexion.

Video Analysis-  Overstriding, heel strike with fully extended knees, Trendelenberg (Right 12 degrees, Left 6 degrees), posterior trunk lean, bilateral feet crossing midline, left knee excessive valgus with a left lateral hip translation in relation to the left foot at midstance.

EMG results during running:

Pre Rehab EMG

 

As you can see, she had a significant asymmetry in her Gluteus Maximus activation while running.

Given these findings, we gave the patient mobility exercises to address her ankle dorsiflexion restrictions, box squats to retrain a fundamental movement, and general core stability exercises to give her a better foundation for functional activity.  Then we started her on a rigorous gluteus medius and maximus strengthening program developed by Chris Powers, PhD. For 3 weeks, 2x/week, the patient performed the Gluteus Maximus and Gluteus Minimus exercises as she watched a live video and sEMG graph.  The purpose of performing it with the video and sEMG biofeedback is to ascertain correct firing of the gluteus medius and gluteus maximus muscles as well as using correct form.

Six weeks later, we retested her sEMG readings of Gluteus Maximus and Medius muscles while running on the treadmill.

Post Rehab EMG

Notice not only is she more symmetrical, but overall Gluteus Medius and Gluteus Maximus activation increased during running just after 3 weeks of glute strengthening exercises.

It is our clinical opinion that video and sEMG biofeedback during rehabilitation exercises allows us to have greater confidence in correct muscle firing during rehabilitation exercises as well as give the patient confidence in the exercises and treatment plan as she can see  improvements during each exercise session.  Pre and Post sEMG data collection while running allows us to monitor improvement and adjust treatment plans accordingly.  Rarely do we have an opportunity to learn how an athlete functions during sport since we cannot perform MRIs, x-rays, or other diagnostic tests during play.  However we feel sEMG allows us to collect diagnostic data during dynamic movements that mimic, if not replicate, an athlete's movement on the field, court, or track.  We no longer have to make educated guesses on how someone is moving solely based on flexibility and muscle testing tests.  We can now actually SEE which muscles are firing or not firing, and which are compensating.

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