During a recent visit to a major Division 1 collegiate athletic training facility we had the opportunity to evaluate a soccer player who was recuperating from recent ACL reconstruction.
We employed vibromyography as an objective assessment of knee muscle balance. This assessment demonstrated a couple of interesting conditions in the athlete that helped to inform the training staff as to how the rehab process was going and the extent to which additional focus was needed on the involved leg in order to approve a return to sport.
Single VMG sensor were attached to the vastus lateralis and the biceps femoris using an elastic strap. The subject was then asked to perform 10 squats. Upon completion, the amplitude of effort generated simultaneously during the exercise by these two muscles was compared through the squatting and rising portions. The exercise was then repeated for the uninvolved leg.
The trainer working with us was impressed by the results, which were immediately available as soon as the subject completed the exercise:
1. it seemed that even at rest, between squats, the subject was clearly favoring his reconstructed leg, as evidenced by the amplitude of his uninvolved quad to support the standing position; and
2. Evidence of classic quad inhibition, but only in the involved leg.
Seeing how efficient the whole process was, from sensor application to instantaneous data analysis, the trainer recruited other athletes to undergo a similar screening. Even at the highest levels of collegiate athletics, there is still a dearth of quantitative data available to trainers and coaches charged with keeping elite athletes on the field. So it came as a pleasant surprise how easy it was to obtain actionable information about an athlete's muscle function.
The trainer noted distinct benefits of VMG assessment versus the two more common assessment methods (electromyography and dynamometry) for assessing rehabilitation from ACL repair. First, VMG assessments are not subject to the well-known constraints of EMG, such as alignment, skin prep, and repeatability. Second, unlike dynamometry, VMG permits assessment during closed-chain real-world activities during which individual muscle effort can be assessed rather than simply joint torque.