Chronic transcutaneous electrical stimulation of calf muscles improves functional capacity without inducing systemic inflammation in claudicants. Eur J Vasc Endovasc Surg. 2004 Feb;27(2):201-9. Anderson SI, Whatling P, Hudlicka O, Gosling P, Simms M, Brown MD.
Abstract OBJECTIVES: To assess whether electrical stimulation of ischaemic calf muscles in claudicants causes a systemic inflammatory response and to evaluate effects of its chronic application on muscle function and walking ability. DESIGN: Prospective randomised controlled trial of calf muscle stimulation. MATERIALS AND METHODS: Stable claudicants were randomised to receive either active chronic low frequency (6 Hz) motor stimulation (n=15) or, as a control treatment, submotor transcutaneous electrical nerve (TENS) stimulation (n=15) of calf muscles in one leg, 3 x 20 min per day for four weeks. Leucocyte activation was quantified by changes in cell morphology, vascular permeability by urinary albumin:creatinine ratio (ACR), calf muscle function by isometric twitch contractions and walking ability by treadmill performance pre- and post-intervention. RESULTS: Acute active muscle stimulation activated leucocytes less (28% increase) than a standard treadmill test (81% increase) and did not increase ACR. Chronic calf muscle stimulation significantly increased pain-free walking distance by 35 m (95% CI 17, 52, P<0.001) and maximum walking distance by 39 m (95% CI 7, 70, P<0.05) while control treatment had no effect. Active stimulation prevented fatigue of calf muscles during isometric electrically evoked contractions by abolishing the slowing of relaxation that was responsible for loss of force. CONCLUSIONS: Chronic electrical muscle stimulation is an effective treatment for alleviating intermittent claudication which, by targeted activation of a small muscle mass, does not engender a significant systemic inflammatory response.
My comments: Electric stimulation parameters of this study were:
- Waveform: biphasic square wave
- Rate: 6 Hz TENS
- Pulse Duration: 250 uS
- Amplitude: an intensity that elicits a visible, pain free muscle contraction
- Electrode location: over the motor point and muscle belly of the triceps surae
- Frequency and duration: 20 minutes performed 3 times per day for 4 weeks
The stim was only done on the worse leg rather than both legs. They were tested by walking on a treadmill at 2.5 kph (1.55 mph) with a 10% incline. Improvements were reasonably impressive increasing pain free walking distance (PFWD) 108% and maximal walking distance (MWD) 50%, which isn’t bad for 4 weeks.
- PFWD increase per week = 27%
- MWD increase per week = 12.5%
- PFWD increase per workout = 9%
- MWD increase per workout = 4.2%
Those increases are not that far different from what one gets with treadmill training and I would expect the treatments to be complementary. I tried the TENS program like above on myself and my patients and thought it would help but I think you would get both increased strength and blood flow with a longer on and off time, 2 on 2 off (EMS pattern feels optimal to me) and I think the EMS current will better increase strength and likely decrease pain better at the same time. I would use a longer pulse width as well with the EMS, up to 450 uS if I had it available. The control group in this study used a very light TENS pattern that did not cause muscle contraction and they had no improvement in function, and that’s what I would expect, it’s the electrically induced muscle contraction that is likely responsible the the improved function, which is why I would expect EMS with a higher intensity, longer muscle contraction and longer pulse with to be better still, though I think a short rest is likely going to better improve circulation than you would get with some more classic strength EMS type protocols.
[Update 4-28-16] I’ve been meaning to take back what I said about 2 second on 2 second off being optimal. I think 2 on 2 off would work but after doing my EMS for aerobics tests I think the 6 hz they used in the study to be nearly ideal. However in my experience 5 hz was slightly better. I still expect a pulse duration of 450 uS to be considerably better than the 250 uS used in the study simply because it will reach more muscle thus further increase circulation. This would be particularly important for those with nerve damage often accompanying intermittent claudication.
As always, if you have any further questions or need for clarifications, please don’t hesitate to ask. Being aware that some of my blog ideas are contentious and occasionally a bit out of the field of my expertise, I encourage my readers to come forth with any questions/comments that are of interest or concern. Your comments are valued and welcomed.
Chad Reilly is a licensed physical therapist, located in North Phoenix, practicing science based medicine with treatment protocols unique and effective enough to proudly serve patients from Phoenix, Scottsdale, Mesa, Chandler, Tempe, Peoria, and Glendale.