By Brian Frank
Personally dealing with neuromuscular inhibition (NI) was what led me to discover EMS (electro muscular stimulation) in 2003 and to become an advocate of the technology. Doing postpurchase EMS consultations with dozens of clients in recent months reminded me how many athletes are living with NI too. Since then, I have found EMS to be uniquely effective in identifying and correcting this common tendency.
I believe NI to be one of the root causes of strength discrepancies between left side and right side muscles seen in most athletes. Strength discrepancies in the leg muscles are also a contributing cause to hip and lower back problems. This is where the body has to counter the rotational torque created by one leg applying more power than the other.
My definition for NI is when a muscle does not fully respond to the brain signaling it to contract. It's almost as if the muscle is partially paralyzed. This can often be seen visually and felt physically when attempting to create a peak contraction where one muscle shows more definition and firmness compared to its opposite counterpart.
In more extreme instances, it can be noted by differences in the circumference of the upper or lower leg. Another means of identifying these underperforming muscles is when doing isolation exercises with resistance. One muscle will be noticeably stronger than its counterpart.
For cyclists, the Spinscan feature of the original Computrainer program and now the new pedal-based power meters that can show the power split between left and right pedals provide another means for measuring power output from each leg. However, if much more than a couple of percent difference is detected, one is still left with limited options for correction. Isolated leg training on the bike or in the gym produces limited results and can easily lead to other problems in the hips and back.
The causes are many - lingering effects from injuries, surgery, structural irregularities, poor biomechanics, and in the case of the glutes and piriformis, from excessive time spent in a seated position - using them as a cushion.
The type of activity an athlete engages in can also be a contributor. Runners tend to have very responsive vastus medialis (the inside of the quad muscle) and somewhat laconic vastus lateralis (the outside) part of the quad. With cyclists, it can be the opposite. Triathletes typically have more active quads, but one will usually still be stronger.
Using EMS to identify NI
When doing EMS demonstrations on an athlete for the first time, knowing nothing in advance about that person, I can usually determine whether they are naturally a stronger runner or cyclist and whether or not they've sustained an injury or had surgery on one leg or the other just by seeing how each muscle responds.
This is done by connecting each muscle in the quadriceps group to one channel of the EMS device, turning on the machine and setting it to the same level of electrical current on all four muscles and noting the different responses in the vastus medialis and vastus lateralis of each leg. In almost every demo I have ever done or witnessed over the past 12 years, one or more of the muscles shows NI of 20% or more, as measured by the amount of electrical current needed to get it to match the dominant muscles.
I recall one athlete, who happened to be a doctor, whom I did a demo on in Kona a couple of years ago. She had surgery on her right knee more than 30 years ago. At 25 ma of current input (a pretty high initial level), her left quad was bouncing vigorously, as would be expected, but the muscles in her right quad were barely twitching at all. I had to use more than double the current going into that quad to get it to respond at all. Upon further questioning, she indicated that quad was prone to cramping and that she had several other chronic issues related to it being perpetually weak, which she'd been completely unsuccessful in addressing up to that point. She bought an EMS unit on the spot.
Different practitioners have different terms for this condition. I've heard kinesiologists, chiropractors, and massage therapists use terms such as "switched off" or "deactivated" to describe a muscle that isn't responsive to peak contractions initiated by brain signals.
My experience with NI
Prior to my discovery of EMS, all my attempts at correction were fruitless. I tried isolated leg training, conventional resistance training,stretching, adjustments, and more. My dominant muscles got stronger and their weaker counterparts barely improved, and the disparity remained constant. This muscle strength imbalance in turn led to chronic hip and back problems that culminated in two ruptured disks in my back. Then I discovered EMS.
Using EMS, I was instantly able to see that my glutes, piriformis, hamstrings, and quads on my right leg were noticeably weaker and less responsive to the same level of electrical current compared to their counterparts on my left leg. I also discovered the cause of the muscles in my left leg being perpetually tight and unresponsive to stretching - they were compensating for the underperforming muscles of my right leg. With daily use of the Active Recovery program and using the Strength programs on alternating days, using higher input levels on the weaker, NI-affected muscles, I was able to get them to contract with the same intensity as my dominant muscles. Today, I have almost no back or hip problems and the difference in strength between my left and right muscles is almost imperceptible.
Note that these are my opinions based on my observations. In addition to increasing circulation and capillary turnover, correcting neuromuscular inhibition and muscle strength discrepancies is another valuable feature of EMS devices. HN