Is the Intensity of NMES Important for Strength Gains?
Neuromuscular electrical stimulation (NMES) is a common modality used in rehabilitation to help restore function and strength of inhibited muscles. As our professions continue to grow and expand our goal of restoring “function,” many have moved away from modalities like ultrasound and electrical stimulation, and probably for good reason. However, I still use NMES frequently in my practice to help kick start my strength recovery after injury or surgery. I like to superimpose NMES on a muscle that is weak or inhibited to help maximize my gains during both simple isotonic exercises and functional movement patterns.
NMES has bee shown in several studies, too many to cite here, to help restore strength faster than exercise alone following surgeries such as ACL reconstruction and total knee replacements. Furthermore, I have publish and presented on how I use NMES for the rotator cuff after injury and surgery as well. It appears that patients that have difficulty activating their muscle have difficulty training their muscles at intensities sufficient enough to promote strength gains.
If you want to learn more about how I use NMES for the shoulder, I have a webinar on this topic at RehabWebinars.com. I definitely recommend you try this as I can honestly say this is something that I do that produces really good results.
A common question regarding NMES involves the intensity of the stimulation. How strong of a stimulation should we be trying to achieve?
Even a Small Amount of NMES is Effective
In my article in AJSM, we reported that peak force production of external rotation with NMES applied was 22% greater than without NMES. Furthermore, the increase in peak force production was not significantly different based on the intensity of the stimulation. Essentially, it didn’t matter how high you turned up the ESTIM, you still saw a nice increase in force production.
Even low thresholds of NMES intensity could result in altered motor unit recruitment and subsequent improvement in muscle function. This doesn’t mean that a small amount of NMES is best, it just means that if you have a patient that doesn’t tolerate a strong contraction, it is still going to provide some benefit and is worth performing.
The More NMES Intensity the Better
A recent study was published in the journal Physical Therapy looking at the relationship between intensity of quadriceps NMES and strength recovery after total knee replacement. The authors concluded that there is a relationship between NMES intensity and change in torque and muscle activation. This is similar to past finds by Lynn Snyder-Mackler and her group that have published extensively on NMES.
While it does appear that “the more, the better” may be true, we should also careful consider the amount of discomfort and, if the patient is postoperative, the tissue healing status. We certainly don’t want to increase the patient’s pain to a level of perceived threat that may cause a negative effect on recovery. Because we know that even a small amount of NMES is beneficial, I generally use the patient’s comfort level as my guide. Patients are often apprehensive when receiving NMES for the first time. As their tissue heals and they become more comfortable, you will naturally be able to raise the NMES intensity to maximize gains. My comment is always “the more the better, but I would like it to be comfortable.”
What has your experience been with NMES? Are you using NMES more or less in recent years, and why?
To learn more about how I use NMES for the shoulder following injury and surgery, check out my webinar at RehabWebinars.com.