E-stim and BFR
December 15, 2016
As payment for rehabilitation services enters into another year of premium increases, out of pocket costs, code changes, and insurance regulation, it becomes increasingly important for our time to be spent well with our clients. Substantial evidence and decision making help us demonstrate the value of our services first and foremost to our customers, and secondarily to physicians, payers, and legislators. With this post, we’d like to explore an emerging use of BFR to assist our clients in achieving the outcomes they desire by the most efficient means possible.
E-stim and BFR
Neuromuscular electrical stimulation (NMES) has long been used to aid recovery and maintenance of size and strength following surgical procedures and other injuries impairing neuromuscular function. However, it’s utility is limited by our physiology and tolerance to the procedure. Therefore, if BFR can enhance NMES’s ability to create muscle adaptation, that would equate to significant value for our clients in this evolving healthcare market. Thus far three studies have examined three different questions regarding NMES’s use in combination with BFR.
Inagaki (2010) demonstrated the ability of NMES + BFR to increase serum GH at a low level of stimulation. They used NMES at 20% of MVC for knee extension, with and without BFR applied to the proximal thigh at 150 mmHg. Ultimately their main research goal was to examine whether or not there is a local metaboreflex vs. centrally mediated control of GH secretion. Their findings demonstrated that there does seem to be a metaboreflex, triggered by lactate build up within the exercised muscle involved in GH secretion from the pituitary. This indicates that we, as clinicians, can achieve an environment within the muscle for our clients that may play a role in their healing, and recovery of size and strength even when their exercise tasks are limited by precaution, pain, or tolerance to the NMES modality.
|Growth Hormone (ng/mL)||Pre||2 min||15 min||30 min|
|NMES w/ BFR||NO CHANGE||NO CHANGE||INCREASE||INCREASE|
|NMES w/o BFR||NO CHANGE||NO CHANGE||NO CHANGE||NO CHANGE|
Gorgey (2016) published a fascinating study using NMES + BFR on incomplete spinal cord injury patients. They sought to determine if they could improve size, strength, and function of the all important wrist extensors via NMES + BFR; thus amplifying, or reproducing without load, results that have already been demonstrated using NMES alone. After six weeks of training, the NMES + BFR group did, in fact, add more muscle size and strength, than the NMES group. The functional increases were similar between groups for “grasp and release” of a soda can, block, weight, and fork, but the BFR group did improve the speed with which it was able to grasp and release a peg. The authors cite many limitations that give them pause in the interpretation of their results but, nonetheless, were confident in claiming that the combination of NMES + BFR demonstrated its potential to achieve desired results without the challenge of externally loading wrist extensors in the SCI population.
Another aspect of the Gorgey study examined flow-mediated dilation of the NMES + BFR group vs. BFR alone. What they found was that the acute dilation of the upper extremity vasculature was amplified in the NMES group vs. the BFR alone group. Presumably, the accumulation of metabolites in the NMES group aided the resultant dilation upon release of the occlusion. The authors conclude that this finding may provide evidence to support a potential contribution of lactate accumulation and nitric oxide release in the role of skeletal muscle hypertrophy.
Natsume (2015) sought to examine NMES + BFR’s ability to increase muscle size, isometric, and isokinetic strength. Part of the problem they sought to address is the fact that NMES’s ability to create muscle adaptation is directly proportionate to the intensity of the NMES used. They cite a variance in tolerance from 12-95% of maximal strength. Subjects underwent twice daily isometric knee extension exercise bouts, five days a week for two weeks, with or without BFR using NMES at a 5-10% intensity of maximal strength. In addition to examining the training period’s outcomes, they assessed the groups after a 2-week detraining period.
|Growth Hormone (ng/mL)||size||isom||90° / s||180° / s|
|NMES + BFR||3.9% INCREASE||14.2% INCREASE||7% INCREASE||8.3% INCREASE|
||NO CHANGE||NO CHANGE||NO CHANGE|
|BFR post||3.0% DECREASE||6.8% DECREASE||1.9% DECREASE||0.6% DECREASE|
In summary, we have evidence to indicate that combining low-intensity BFR with NMES can increase muscle size and strength in healthy and neurologically impaired populations, as well as positively affect blood flow to the exercised region. We also have gained some insight into whether or not growth hormone release is centrally or locally mediated. It seems it is at least partially facilitated via metabolite build up in the limb.
Given these studies and others amongst the BFR literature, we’d like to make some recommendations for parameters of use when combining BFR and NMES.
Maintenance of size and strength: Combine a swelling protocol with NMES.
|NMES 10" on 10" off / intensity as high as tolerated by subject|
The subject should provide a concomitant isometric contraction of the targeted muscles. Given research that has demonstrated superior results using external focus vs. internal focus, when possible we suggest fixing the joint in a mid-range position and having the subject push into an immovable object vs. merely clenching the targeted muscle. This does get lengthy. Not considering set-up, it takes 37 minutes to complete this protocol. In a clinic setting, it is likely best done at the end of the session as the patient can be left unattended for extended periods. One might also consider reducing rest periods to 1-2’ and removing a repetition or two to reduce length. Evidence would suggest that twice weekly application could be sufficient. However, it is likely that the more frequently this can be executed, the better the results will be. There is no indication that applying more than twice daily is necessary.
Thank you, Kyle Kimbrell PT, MPT for the article summary.