Functional electrical stimulation (FES; e-stim) has been around since the late 19th century. Seen as a way to enhance existing function today, small portable units can be employed to stimulate and strengthen weak leg muscles, enabling people with significant muscle sparing to walk. Implanted e-stim units can enhance hand function and grip, with the user activating the unit with specific shoulder movements. Ditto for bladder control — a “pee-on-demand” system. Over the past decade or so, implanted units have been offered as an alternative to vents, enabling people to breathe on their own, free from the bulk and noise of external units.
Christopher Reeve’s advocacy brought attention to FES’s potential to enhance return of function and begin to retrain muscles. While no blockbuster breakthroughs have yet to emerge from all this work, researchers and clinicians continue to toil, tinker and experiment with FES to find ways to benefit people dealing with a variety of neurological conditions ranging from spinal cord injury to multiple sclerosis to stroke.
One such benefit is heart health.
Cardiovascular disease is the leading cause of death among people with SCI, with reported rates ranging from 30 to 50 percent. The SCI population is plagued by numerous other chronic diseases and conditions, including obesity, high cholesterol levels and adult onset diabetes.
A major risk factor for cardiovascular disease and early death is physical inactivity, which has been linked with cholesterol problems, increased fat and glucose intolerance — the inability to properly metabolize blood sugars and a precursor to diabetes.
The fact is, for most people (and especially wheelers), ordinary activities of daily living do little to maintain cardiovascular fitness. Additionally, SCI wreaks havoc with cardio-metabolic health, particularly for those with injuries above T6. However, as little as 30 minutes of moderate daily physical activity, combined with a 5 to 10 percent loss in body weight can lower the chance of developing diabetes by 58 percent. Regular cardiovascular or aerobic exercise can also help raise the level of HDLs (good cholesterol) and reduce the risks for CVD.
Therein lies the rub: Just how do wheelers get exercise — at a sufficient intensity — that they need? SCI poses numerous obstacles to beneficial exercise: limited muscle mass, lack of any weight-bearing below level of injury and, because the legs are not engaged, the absence of the body’s largest muscle mass to pump blood, to say nothing of the autonomic system problems caused by cervical injuries. And there’s always the risk of overuse injuries to body parts critical to daily living.
Aerobic or cardio exercise is demanding enough to elevate the heart rate to between 60 and 85 percent of maximum heart rate (MHR = 220 minus your age). Sixty percent MHR is a fitness and fat burning zone achieved through moderate exercise such as doubles tennis or bike riding. Seventy percent MHR gets you into a significant cardiovascular and endurance training zone, often achieved through distance running, singles tennis or perhaps basketball. Eighty percent MHR reaches the anaerobic zone, a level too taxing to sustain for very long, such as sprints and dashes.
In order to gain significant benefits, one needs to sustain exercise in the 60 to 80 percent MHR zone for 20-30 minutes or more (a pace or intensity sufficient to induce sweating and at least somewhat labored breathing). Without the engagement of large leg muscles and blood pumping, many wheelers have difficulty approaching even 60 percent of maximum heart rate, the fat-burning/weight control range. Using FES to engage the legs changes the game. It offers wheelers access to the joys of aerobic exhaustion and that lactic acid burn of overtaxed muscles. The upside is the treasure trove of potential health benefits that come with physical fitness and being in shape, such as better blood pressure levels, better circulation, decreased fat, greater muscle mass, more energy and increased stamina, and improved mental health due to stress and depression reduction.
The ability to predict maximum heart rate comes with wide variability, with as much as one third of the population falling outside those guidelines. Injuries above T4 or so may impair the heart’s ability to increase with exercise, all the more so with higher physical injuries, to less than 130 beats per minute.
But there’s still hope and promise. NEW MOBILITY takes a look at two FES modes of use here: stationary bikes and stationary rowers, both of which are facilitated with FES. While each has a different focus and goal, each shows promise as a potential gateway to meaningful gains in physical function, improving quality of life and most important for the purposes of this article, enhancing long-term health through significant cardiovascular exercise, a feat seemingly out of reach for most wheelers.
Restorative Therapies FES Bike
Dr. John McDonald worked with Christopher Reeve back in the ’90s. Spend some time discussing e-stim bikes with him today and you’ll come away wondering why all wheelers aren’t in such a program.
“We found that FES cycling is a practical form of exercise that provides substantial benefits,” he says, “including improved physical integrity, increased muscle size and strength, reduced muscle spasticity, improved quality of life and enhanced neurological and functional performance.”
Those are the results of a two-and-a-half year study McDonald conducted while at the Washington University SCI Program in the early 2000s. The study also claimed that FES cycling enhanced muscle strength without increasing spasticity, with FES bikers reporting lower frequency of use of anti-spasticity medications in lower doses than their control group counterparts. Overall, bikers were found to have nearly 45 percent less intramuscular fat in their thighs than control group subjects, which would suggest a lower risk of glucose intolerance and diabetes, complications which plague a large portion of SCI survivors. Acceptance of those benefits is widespread.
More controversial are McDonald’s claims of 80 percent of the e-stim bikers experiencing improved motor function and a majority experiencing “clinically important gains” in neurological function, defined as, among other things, improved light touch and pin-prick sensation. Subjects in the control group scored much lower in all areas. McDonald asserts that 70 percent of the FES bikers experienced “significant neurological gains,” defined with similar rigor as functional gains. In general, the study associates FES cycling with improvements in quality of life as well as improved overall health.
McDonald says all these gains most often show up within three months of starting a regimen of three one-hour sessions/week. As with any exercise program, biking must be ongoing at that level or the gains could quickly evaporate.
McDonald is forceful and enthusiastic when speaking of the neurologic benefits and gains experienced by the study’s subjects, who were injured an average of eight years. He says this offers further proof of FES cycling’s value.
The study’s findings have passed peer-review but are not yet in print. The authors acknowledge that the study is not a true randomized controlled clinical trial — the usual gold standard. Randomized controls ensure against numerous independent variables outside of FES that could influence the outcome. The absence of those controls may be a barrier to widespread acceptance. Still, McDonald’s study is the first to pass peer review that links FES to improved neurological gains.
His enthusiasm borders on evangelical when speaking of who could benefit: “Everyone, regardless of age or number of years post injury,” he claims. “People with incomplete injuries or those already very active can increase heart capacity and oxygen volume by using their legs. Most of our participants report enhanced quality of life. They’re more independent because they can do more of their own care, can transfer better and have more confidence. They see these changes in their lives and realize they have more control.”
McDonald sees the bikes as an avenue to “moderate physical activity, somewhere in the range of 60 percent MHR, 65 percent max.” Interestingly, faster/harder isn’t always better; studies have shown cardiovascular and muscle metabolism responses both to be independent of pedaling cadences. Twenty-five rpms yielded essentially the same effects as 50 rpms.
McDonald’s program at the Kennedy Krieger Center for SCI caters strictly to chronic injuries. People come to the center for an intense two-week program to optimize physical activity through intensive treatments ranging from bikes to pool therapy to walking, while monitoring function throughout the process. People leave with what McDonald refers to as a life-long program.
“Physical activity is a necessary part of life for everyone,” McDonald asserts. The cycling can be done at home, which is where this needs to go, rather than people coming to a center to work out. “Life-changing improvement is possible.”
Two FES Bike Advocates
Patricia Pogodzinski has been using an e-stim bike since 2004. Clearly, she likes it and the results.
“It keeps my muscles from atrophying,” says the 22-year-old C7 quad from Baltimore. “It also gets my heart pumping some, though I have no idea how high. I like that.”
Pogodzinski, who graduated from the Maryland Institute of Art 10 years after injury, initially used an older model bike before acquiring her own RT200, which she uses at home three times a week, about an hour at a time.
“I feel it keeps me in shape and gives me the benefits of regular exercise. It keeps me fit and my weight under control and also is good for circulation. I like the way I look. I haven’t had any real problems since using the bike. In fact, I’ve seen some functional gains. My posture is better, I think I have more endurance and many activities of daily living like dressing and transfering are easier. I definitely notice a difference in my posture and endurance if I don’t use the bike for a while.”
Nick Solomon, a C4-5 quad who lives outside Washington, D.C., is also a big advocate of e-stim biking. Solomon began using an RT300 model while still in rehab eight years ago and hasn’t stopped.
“I think it’s the best way for me to stay in shape. I played football and was always active before injury. The bike helps me stay active. I want the muscles to still be there in case there’s some kind of breakthrough.”
Solomon owns his bike and says he rides it for an hour or so each day, six or seven days a week. “I have fairly normal looking legs, which is good because the babes at the bar don’t like scrawny legs. I have to believe there are other long-term health benefits.” Presumably those benefits would be cardiovascular, controlling lipids and glucose tolerance, weight control and possibly mental health.
Solomon is presently involved in a Kennedy Krieger program to raise awareness of SCI, a “Ride Across America.” E-stim bike riders track their miles in a quest to pedal “ocean to ocean.” Solomon’s logged 1,600 miles so far, about halfway there.
E-Stim and Rowing
Looking for some genuine nondisabled-type cardio exercise? Go see Dr. Andrew Taylor and Glen Picard, M.A., in Boston. They’re running the Exercise for Persons with Disabilities (ExPD) program, an e-stim rowing program out of Spaulding Rehab SCI program, targeting people with SCI, CP, MS and peripheral neuropathy. The pair both have backgrounds in exercise and physiology and have been in the research field for years. Coupling a stim unit to trigger the legs with an adapted Concept2 stationary rowing machine, they’ve managed to achieve whole-body aerobic training at impressive levels, as high as 85 percent of maximum heart rate capacity.
The methods and technology for e-stim rowing were pioneered in the United Kingdom and introduced in the U.S. about six years ago at an annual international indoor rowing competition held in Boston. That’s when Taylor and Picard got involved and secured funding for a study which grew into a program now involving 50 people with SCI and MS.
“Our program isn’t about e-stim per se, but e-stim is a very important part of it. We use the e-stim to trigger the legs and allow a SCI individual to get a form of whole body exercise using both the arms and the legs. The e-stim allows individuals access to exercise similar to that of the nondisabled. We use the e-stim first to activate the quadriceps and push the body away from the erg, then we stimulate the hamstrings to bring the body back to what’s called the catch position. The user is in control and must press a button on the handle of the rower to trigger the stimulation. E-stim bikes offer a relatively passive type of experience — people are reading or drinking coffee. Our program is very individual-involved and demanding; we’re actually increasing aerobic capacity, oxygen consumption and metabolic demand.”
The program, begun with funding from the Department of Defense and the National Institutes of Health, evaluates people upon entry and provides them with an individual program tailored to their specific needs and fitness level. The typical program usually combines arms-only rowing and FES rowing in a progressive fashion to build strength, stamina and overall fitness. The goal from the outset has been to provide meaningful exercise with significant health benefits. Taylor sees the program as potentially becoming the standard of care.
“The pilot study was about whole body exercise — oxygen consumption and metabolic demand,” Taylor explains. “Once we achieved those goals we began to look for other benefits. We’ve seen improvements in blood lipids, changes in body composition and bone density. The implications are quite large.”
Taylor repeatedly emphasized that the ExPD is exercise rather than therapy, and as an exercise physiologist, he believes meaningful exercise involves work, sweating and heavy breathing, a combination, he says, not often associated with the e-stim bike.
“Not all e-stim is created equal,” he says. “I don’t like to compare our program with the bikes or the NuStep because I think the goals are different. We’re loading the muscles as much as possible in order to gain the maximum benefit, which is an order of magnitude greater than with the bike. With rowing, a person is moving his entire body weight with his legs with every stroke while using the arms to achieve whole body exercise. The stim unit lets us activate and involve the body’s largest muscle mass, increasing aerobic capacity, and incorporates the upper body muscles in a fairly simple linear motion to do that. This is a progressive type exercise which increases fitness and provides tangible benefits.”
“The added health benefit for wheelers,” adds Glen Picard, “is that engaging both the upper body and lower body together results in a higher intensity of exercise, more like the able-bodied. Think of it as more muscle mass equals more intensity equals more benefit. Just stimulating the legs alone may not get to the level of intensity needed to reap health benefits.”
While the equipment is much more affordable than the bike ($3,500 versus $20,000), many participants also prefer to go to the center to work out, citing the social aspects and benefits of getting out and interacting with like-minded people. They enjoy the camaraderie, access to the local rowing community and the opportunity to actually get out on the water.
“Rowing is a big sport here [Boston], and our program gives people access to clubs, competition and a larger circle of social interaction.”
An Intense Workout
Mike Mahoney, a Boston attorney whose age is “somewhere north of 50,” was an active guy prior to a diving accident at 21 which left him a C6-7 quad. First law school and then a busy practice got the better of him and he ballooned to 173 pounds before he began using a stationary hand cycle and a home gym, which helped him get back down to 130. Since he got involved in Spaulding’s ExPD last October, he’s shed another 10 pounds and now says he’s “54 going on 30.”
“It feels like a good workout to me — the cardio is incredibly intense. Combined with a good diet and the lifting I do, it’s made a big difference with my shoulders, my stamina, my breathing. Transfers are much easier, I sleep better and have more energy. Bowel programs are no longer an issue, nor an apprehension. I’ve got four kids, three of whom are under 8, and I figured I owed it to them and to myself to be as healthy as I can. I’m in better shape than when I was 30.”
Once in the rower, Mahoney does seven minutes of whole body rowing with the use of the FES unit, followed by a two-minute rest. Then he does seven minutes of arms-only rowing and another two-minute rest. He does this routine three times each session.
“I can go much faster doing arms only because my legs get fatigued. I go from a resting heart rate of 75 up as high as 150.”
That’s approximately 90 percent of his maximum heart rate, a level of intensity not sustainable for long periods of time. Including travel time, Mahoney estimates he’s investing at least seven hours a week in the program, time he considers well spent. He thought about buying a unit for home but decided to continue commuting instead. “I like going to the center. It’s a good, positive atmosphere. There are people around you and you feel extra motivated. I enjoy the social aspect and the camaraderie of working out with others.”
Dave Estrada, a 41-year-old T4 para, got into the rowing program on the ground floor. Injured 18 years, Estrada’s been rowing for six of them and is a big advocate. “What I like most is that this is a whole-body cardio workout. The e-stim has given me more muscle mass and better circulation. I’ve seen edema decrease dramatically.”
Estrada rows three days a week, 30 minutes a session. He’s even had an adapted scull out on the water. He estimates his usual time commitment per session to be about 30 minutes travel time, five to 10 minutes of set-up and a half-hour of rowing.
“Bone scans confirmed I’ve reversed osteoporosis and increased muscle mass. I feel as if I have more back muscle and certainly more trunk control. I know I have more energy. Pushing my chair is much easier and not nearly as fatiguing as it once was. I’ve noticed an increase in appetite and feel it’s helped with bowel function as well.”
Estrada, who serves as executive director of the Greater Boston Chapter of the NSCIA, says he prefers rowing at Spaulding “because it’s a great place to work out as well as meet and talk to others with SCI. It gives us a place to talk about SCI-specific issues and learn from other wheelers.”
E-Stim Poised for New Growth?
Other facilities, often SCI rehab facilities such as Craig in Denver or Shepherd in Atlanta, offer e-stim bike access to the wheeler community. They cite the same general goal of fitness as a way of pursuing maximal wellness and function. They normally cite the same basic necessity of two to three bike sessions weekly and ongoing commitment in order to reap and maintain real and perceived benefits.
Other such programs are also exploring e-stim for fitness. A University of Delaware program run by Sam Lee is looking to reduce risk of obesity, CVD, diabetes and other chronic diseases, reduce spasticity and reach maximum function by putting kids with CP in e-stim recumbent tricycles they can actually take outside, play with and use to explore the world.
Vickie George of Yes U Can in Delaware is working with University of Delaware mechanical engineering seniors to adapt a hands-free recumbent bicycle for individuals with physical disabilities, and another for customizing a boat for disabled rowers.
It would seem riding an FES bike resembles anything from a stroll to a brisk walk, whereas getting on the rower is more like long distance running, interspersed with some sprints. Both these FES programs yield substantial benefits, though the focus and intent may differ. McDonald kept going back to the potential for neurologic gains, with those substantial health benefits almost secondary. Taylor and Picard, on the other hand, are clearly focused on hard-core exercise, looking to wring every last drop of health benefit from it they can.
What can be said of both with certainty (with scientific backing) is that they have been found to reduce muscle spasticity and muscle atrophy, while improving blood circulation and range of motion.
The Changing Role of FES
Functional electrical stimulation (FES or simply E-stim) comes in several forms and has various goals. Long seen as a tool to enhance function, FES has been used as an alternative technology for mechanical vents, enhanced bladder and hand function, and to stimulate leg muscles to facilitate walking. Now it’s being used to facilitate an ongoing exercise program and to tap into an array of health benefits, such as increased glucose tolerance, altered cholesterol levels, greater muscle mass for skin protection, decreased edema, better core strength, and lower overall cardiovascular risk levels.
Two FES Programs
Kennedy Krieger’s Wellness Program gives people in the community access to the program’s therapy equipment. Rates vary, but are said to be comparable to local gym membership prices. People interested in using the therapy equipment as a part of this program must be referred by a Kennedy Krieger physician.
Spaulding’s ExPD program charges a monthly $50 for rental of the stim unit and $100 for the program, to cover electrode pads, batteries and other supplies. Home users pay a monthly charge of $5 plus the $50 rental stim unit fee and cost of necessary supplies. Presently the stim unit being used is from the UK and only has FDA institutional use approval. The center is looking at other units commercially available and appropriate to the program. Spaulding also has a scholarship program to assist participants that cannot afford the program.