Jan 29, 2015
Pooling Resources

Aquatic therapy creates dynamic, controlled resistance. Biofeedback offers quantifiable information about muscle function. Together, they allow athletes to begin rehab in a supportive, pain-reducing environment.

By Ron Fuller

Ron Fuller, PTA, is the Director of Aquatic Rehabilitation for Elliot Health Systems in Manchester, N.H., and an adjunct faculty member at Franklin Pierce College, where he teaches aquatic physical therapy and advanced orthopedic techniques. He is on the teaching faculty of Aquatic Consultants of Georgia and the clinical faculty of the Biofeedback Foundation of Europe. He can be reached at: [email protected].

If you’ve been in the athletic training or physical therapy world long enough, you’ve no doubt met athletes who come in looking for a miracle cure, an instant fix, or the “one treatment and I’m ready to go back in” remedy. As highly trained professionals, we know that rarely–if ever–is there a single cure-all that will live up to those expectations.

But every once in a while, something comes along that represents true progress in that direction. Whether it’s a new treatment, a new application for an old treatment, or a combination of protocols that have never been tried together, we are always on the lookout for ways to give our rehab patients better outcomes.

I have recently enjoyed great success combining electromyography (EMG) biofeedback with aquatic therapy. On their own, each protocol has proven itself to be a credible and effective training tool. Together, I believe they enhance one another in exciting ways. Since I’ve implemented this pair of modalities into my practice, they’ve taken my clinical treatments to a new level.

A Natural Combination

On land, therapists and athletic trainers utilize surface EMG biofeedback to target specific muscle groups when they want to address weaknesses, relax tight or overworked muscles, and correct dysfunctional muscle postures and movements. Armed with specific information about what the targeted muscles are doing, the therapist and the athlete can better understand whether specific movements and corrective exercises are achieving their goals and how they can be altered to work even better.

EMG biofeedback works by exposing what a muscle is doing. It involves a locally attached sensor, typically a small needle or a surface electrode, that can detect “electrical potential” within muscle tissue to determine how hard it is working. Today, powerful handheld EMG biofeedback units provide information about the musculoskeletal system that earlier generations of athletes could only dream of knowing. As a result, rehab and training techniques can be more focused and deliberate.

How do you enhance those benefits? Just add water.

By combining EMG biofeedback with aquatic therapy, I’ve been awakened to a whole new realm of possibilities. The natural properties of water–buoyancy, hydrostatic pressure, and resistive drag–allow me to strengthen, relax, and correct musculoskeletal deficiencies in a more supportive, pain-reducing environment. The biggest advantage to combining these two therapeutic tools is that the partnership allows me to start the rehab process sooner and return my patients to their previous level of function more quickly.

As a rehab tool, aquatic therapy offers several well-documented advantages, primarily because it allows for highly customized workouts. Water can unweight the body to varying percentages depending on the depth of immersion–the deeper the pool, the lower the weight burden. As a result, joint compression can be decreased to make exercise less painful, particularly when rehabbing a joint injury or following surgery.

The turbulent drag that water provides allows athletes to modulate the resistance of the exercise to whatever degree of difficulty they can tolerate. In this highly dynamic workout environment, resistance is applied in virtually every plane of movement, and can be adjusted by altering the movement speed and direction.

The fundamental principles of aquatic biofeedback are not complicated–I take the same techniques I use on land, and simply take into account the changes in resistance and weight load introduced by the water. Whether on land or in water, biofeedback allows me to evaluate specific muscles, and decide tactical approaches for strengthening (up training), relaxing (down training), developing bilateral symmetry, or correcting muscle strength ratios.

Still, not everything is the same in the pool as on land. Buoyancy and aquatic resistance can affect the data collected by the biofeedback unit and those differences must be taken into account during aquatic rehab sessions. For instance, if I am testing an athlete’s quads during an underwater walking movement, the output will be lower than during a similar movement on a dry-land treadmill. The resistance created by water is outweighed by the gravity reduction of buoyancy, resulting in reduced overall muscle recruitment. The deeper the athlete is submerged during the movement, the greater this effect.

In addition, turbulent drag can produce irregular recruitment patterns on the biofeedback unit screen, due to the varying amount of effort aquatic workouts require. Movement of the extremities through water is rarely consistent from one repetition to the next. I have found the best way to interpret aquatic biofeedback data is to view it as a “big picture” guideline. I try to keep the variables and movement patterns as precise and consistent as possible, but I don’t micro-manage individual phases of the workout or expect athletes to produce the same consistent muscle effort as they would during a dry-land biofeedback session.

Backed by Research

Aquatic EMG biofeedback is largely a new frontier for rehab and athletic training applications. But there is a small body of research evaluating its effectiveness. Several articles have been written looking at aquatic EMG not only for use with athletes and rehab patients but also for its potential to aid in the diagnosis and treatment of certain biomechanical conditions.

Below is a summary of the research articles I have found most useful as I’ve applied aquatic biofeedback in my setting. It’s not a comprehensive list, but these studies have produced some of the key findings in this area of treatment.

• In 1986, authors Nuber, Jobe, et al., published an article in the American Journal of Sports Medicine after attempting to observe the shoulder muscles of swimmers using fine wire EMG. Small needles were inserted bilaterally into specific muscles and a telemetry system was used to analyze the firing sequence of the shoulder musculature during several swim strokes.

This research had several important results. First, it established baseline data on the firing sequence of the shoulder muscles during swimming, which would be subsequently expanded upon by other authors. Second, it showed that the use of EMG needles in strong muscle groups during a fast, repetitive movement may not be the best way to gather data. Occasionally, the needles were accidentally pulled out of the muscle during the swim strokes, revealing an important limitation of this type of testing. Third, it helped establish EMG as a valuable tool in unlocking the secrets of the human musculoskeletal system and spurred greater curiosity about this modality in the sports medicine field.

• Ten years later, authors Becker, Erlandson, et al., conducted research at the College of St. Catherine comparing the muscle activity of the serratus anterior during prone exercise in water and on land, using an EMG biofeedback unit to gather the data. This was the first article to compare aquatic exercise to land exercise, and it helped show the medical community that aquatic exercise was both valid and, more importantly, quantifiable.

• In 1999, I collaborated with Brian Awbrey, MD, and others to publish an article in the American Physical Therapy Association’s Journal of Aquatic Physical Therapy that compared the muscle activity of the vastus medialis oblique (VMO) during a single-leg mini-squat on land and in water at varying depths. Our research found that the VMO activity generated in waist-deep water was 50 percent of that generated on land. In chest-deep water, the activity was reduced to 25 percent. This correlated well with other studies showing similar immersion-weight reduction ratios. It also made intuitive sense: If your body weight is reduced by half because you’re half underwater, you should only need 50 percent of normal muscle recruitment to perform an activity.

In addition, we found that performing closed-chain exercises in varying water depths allowed the physical therapist or athletic trainer to exert greater control over the exercise, thus allowing rehabilitation to start earlier after injury. We used a sample of 50 research subjects, making it one of the most extensive studies on the topic to date and adding further validity to aquatic biofeedback as a rehab protocol.

• Authors Kelly, Roskin, et al., published a paper in the Journal of Orthopedic and Sports Physical Therapy in 2000 based on their research into the shoulder rotator cuff musculature working at three different speeds of movement on land and in water. Observing movements ranging from 0 to 90 degrees in the scapular plane, they found that muscle activation at the slower test speeds (30 degrees/second and 45 degrees/second) was significantly lower in the water than on land. This result implied that using aquatic therapy for early movement after surgical rotator cuff repair would not compromise the surgery site or the surrounding tissue, because the movement is performed at slower speeds. Safe, early active movement is an important consideration in restoring normal joint kinematics, so this finding was significant.

• In 2001, I collaborated with Thom Stowell, DC, DPT, and George Fulk, DPT, to explore the possibility of using an aquatic environment to improve the motor function of a subject who had suffered an incomplete spinal cord injury. Our hope was to mimic the effects of a harness-assisted body weight gait training system. We used EMG biofeedback both on land and in the water to assess muscle activity and recruitment, as well as to direct the aquatic exercise routines.

We observed one very interesting trend during our three months of outpatient treatment sessions: EMG output of the lower extremities increased both on land and in the pool. This revealed that the patient’s general function and mobility were improving, even though Manual Muscle Test (MMT) results remained unchanged. When we published our research in the Journal of Aquatic Physical Therapy, we wrote that EMG biofeedback played a key role in the patient’s rehabilitation, and speculated that it might have significant potential in treating individuals after spinal cord injuries.

Practical Application

What does an aquatic EMG biofeedback workout actually look like? The sample workout below was designed for a patient suffering from patellofemoral pain syndrome.

1. Water walking forward, backward, and sideways, with a focus on slow, exaggerated steps and a normalized gait pattern. 2. Bilateral lower extremity PRE’s (straight-leg flexion/extension and abduction/adduction). 3. Three-way tethered mini-squats with EMG biofeedback. 4. Step-ups and step-downs with EMG biofeedback. 5. Forward step-up sequence. 6. Deep-water scissors. 7. Deep-water abduction/adduction. 8. Deep-water mini-squats on a board with EMG biofeedback. 9. Deep-water “up-out-open-close-in-down.” 10. Deep-water bicycles.

As patients make progress, I add variations of all these exercises to introduce greater challenges. For instance, as their endurance level and overall conditioning improves, I’ll increase the number of reps or the speed of the exercise, or I’ll add resistive equipment. I will also tape the patella while the patient is in the pool to promote normal tracking.

The EMG biofeedback unit displays the level of muscle activation created by each modification I make, and the patient keeps me updated on their pain level. Using those two guides, I’ll adjust the depth of squats, range of motion, immersion level, and other variables.

An Emerging Modality

Aquatic biofeedback allows therapists to work on specific muscles and focused techniques early in the rehabilitative process. It provides a new level of control and specificity. And because it reduces pain, it can help make rehab less difficult and ultimately more beneficial for athletes.

I strongly believe that aquatic biofeedback has a bright future in athletic training facilities and rehabilitation clinics. Since I’ve begun using this approach, the success I’ve seen has convinced me that it can be an effective tool for athletes in a wide variety of rehab and training situations.

To view complete references for the published research mentioned in this article, please go to: www.training-conditioning.com/references.

Sidebar: Wiring Up

Early on in the development of aquatic EMG biofeedback, it became glaringly obvious that the ability to waterproof the electrical sensors was crucial. Any water coming into contact with the sensors would cause a short out, rendering that sensor ineffective. Another problem was the effect of chlorinated water on the delicate circuitry of the sensors. Simply put, surface EMG biofeedback equipment was poorly suited for the aquatic environment.

Through trials and (many) errors, I have settled on two reliable methods of “waterproofing” EMG sensors. The traditional method is to use a bioclusive barrier to cover the sensor. A newer method uses a latex “sock” to cover the extremity being tested. With either method, the sensor placement and application are the same as on dry land.

With the bioclusive barrier method, I always use a skin prep wipe to ensure that the barrier will stick to the skin. The sensor and surrounding area are then covered with the barrier, and the exit wire is sealed tightly so that no water can migrate to the sensor. The lead wires are then connected to the biofeedback unit before the patient enters the water.

The patient wears the EMG biofeedback unit only for certain exercises. The bioclusive barrier is effective for about 30 minutes, but will eventually start to pull off due to immersion and physical movement.

Sidebar: Beyond EMG

The therapy discussed in this article involves one segment of the biofeedback spectrum: electromyogram (EMG) biofeedback designed to sense muscle tension and activation. But biofeedback is an umbrella term encompassing several different types of treatment, and biofeedback units are now available to detect everything from heart rate and blood pressure to brain activity.

One of the most promising applications for biofeedback in athletic settings centers on its ability to prolong the effectiveness of pain-management protocols. When used in conjunction with electrical stimulation, a device that incorporates biofeedback can provide more targeted, longer-lasting pain relief.

For instance, transcutaneous electrical nerve stimulation (TENS) is well known in the sports medicine community as a pain-relieving modality. But as the nervous system becomes habituated to an electrical stimulus, the treatment becomes less effective and the pain can return. A biofeedback device can be used to sense the response of soft tissue to electrostimulation, and by altering the intensity and delivery of the current accordingly, it can prevent habituation to TENS.

Other uses for biofeedback include alternative medicine and mind-body therapy for the treatment of conditions ranging from high blood pressure to asthma and from attention deficit hyperactivity disorder to epilepsy. According to the Biofeedback Certification Institute of America (BCIA), “[Biofeedback] signals typically measure skin temperature, muscle tension, and/or brainwave function. With this information, patients can learn to make changes so subtle that at first they cannot be consciously perceived. With practice, however, the new responses and behaviors can help to bring relief and improvement to a variety of disorders.”

References for this article can be found here.

For more information, visit the BCIA online at: www.bcia.org. — Greg Scholand


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