Musculoskeletal disorder patients have intact proprioception. Biofeedback applications include blepharospasm, fecal elimination disorders, urinary incontinence, meniscectomy, and muscle-tendon transfers.

Meniscectomy (removal of knee cartilage) is a representative musculoskeletal application. Following surgery, these patients show generalized muscular weakness due to cartilage and ligament damage. A clinician attempts to increase motor unit recruitment (number of motor units and rate of firing) to restore strength and function.

This unit covers General treatment considerations (IV-D) and Target muscles, typical electrode placements, and SEMG treatment protocols for specific neuromuscular conditions (IV-E).
Students completing this unit will be able to discuss:

  1. General treatment considerations
    A. Standard physical rehabilitation techniques and procedures
    B. SEMG biofeedback techniques used to improve motor control
    C. Use of SEMG biofeedback to promote relaxation in clients with spasticity and rigidity
  2. Target muscles, typical electrode placements, and SEMG treatment protocols for specific
    neuromuscular conditions
    A. Urinary and fecal incontinence

Blepharospasm involves spasm of the eyelids characterized by bilateral blinking. The responsible muscles are the orbicularis oculi that surround the eyes. Symptoms range in severity from increased blinking and periodic eyelid spasm to ocular pain, facial spasms, and disabling interference with vision. Their functional blindness may prevent normal activities that depend on vision, like driving, reading, viewing television, and walking. Anxiety, depression and suicide, inability to perform their job, and social withdrawal are common reactions (Saulny, 2005).

There are an estimated 50,000 cases of blepharospasm in the United States, with 2,000 new cases annually, and a prevalence of 5 in 100,000. This disorder is more common in women than men (1.8 to 1). Blepharospasm is first diagnosed at 56 and two-thirds of these patients are 60 or older (Saulny, 2005).

SEMG biofeedback can be used to reduce spasticity in the orbicularis oculi muscles. Miniature (0.5 cm) surface electrodes are placed over these muscles. Patients are instructed to reduce the elevated SEMG levels associated with muscle hyperactivity. Home practice may focus on spasm suppression using a mirror for feedback.

The orbicularis oculi muscles (shown below) are located around the eyes.



Below is a BioTrace+ / NeXus-10 screen that provides SEMG biofeedback to help clients learn to relax. This screen shows a water lily digital water ripple effect to teach SEMG relaxation. The water surface will become 'quieter' as the SEMG levels decline. This display also shows the percentage of time the client's SEMG level exceeds the training threshold.

Fecal incontinence is the involuntary release of feces or gas due to loss of anal sphincter control. The diverse causes of fecal incontinence include congenital abnormalities that damage the spinal cord, and anal sphincter damage due to vaginal delivery, surgery, inflammatory conditions, and cancer, inflammatory bowel conditions, and medical conditions, including diabetes mellitus, stroke, spinal cord trauma, and neurodegenerative disorders.

Nelson and colleagues (1995) reported a prevalence rate of 2.2%. The incidence of fecal incontinence is 8 times higher in women than men. Childbirth is the most common predisposing factor to fecal incontinence because it may disrupt the internal or external anal sphincter, or damage the pudendal nerve (Seymour, 2002).

When peristalsis transports fecal material from the sigmoid colon to the rectum, pressure on the rectal wall triggers a defecation reflex. Firing of sacral spine parasympathetic motor neurons shortens the rectum, increasing pressure on fecal material.

The involuntary internal sphincter is opened by increased pressure within the rectum, voluntary diaphragm and abdominal muscle contraction, and parasympathetic stimulation. Intentional relaxation of the voluntary external sphincter expels feces, while constriction postpones defecation (Seymour, 2002).

Biofeedback should only be initiated following medical evaluation and conducted under medical supervision. Two major training procedures include an anal EMG probe and three-balloon manometry (pressure) system.

The anal EMG probe, based on John Perry’s vaginal Perinometer, detects muscle activity associated with the external anal sphincter.


Continence training teaches the patient to increase external rectal sphincter strength to prevent unwanted voiding of feces and to develop proprioceptive cues so that signals from rectal wall stretch receptors will contract the external rectal sphincter to prevent leakage.

A Thought Technology Ltd. U-Control home continence trainer is shown below.

A manometry system places one of three balloons (Schuster anorectal probe or others) in the anal canal to simulate movement of fecal material, adjacent to the internal rectal sphincter, and adjacent to the external rectal sphincter. As the anal canal balloon is inflated, polygraph tracings show contraction of the internal and external rectal sphincters. Training is designed to teach the patient to contract the external rectal sphincter (preventing leakage of feces) when the anal canal balloon expands, activating rectal wall stretch receptors.

Adjunctive training procedures used in addition to biofeedback include bowel or habit training, dietary counseling, medication, home program including logs (normal bowel movements and incontinence episodes), and daily sphincter control exercises.

Biofeedback has been effective in children diagnosed with fecal incontinence and encopresis (constipation), and in adults with chronic fecal incontinence and incontinence due to obstetric complications, and constipation. Several researchers have shown that patients maintain continence at long-term follow-up. Biofeedback does not correct incontinence caused by surgery to correct rectal prolapse.

Evidence-Based Practice in Biofeedback and Neurofeedback (2004) rates biofeedback for fecal elimination disorders at level 3 efficacy, probably efficacious. The criteria for level 3 efficacy include "Multiple observational studies, clinical studies, wait list controlled studies, and within subject and intrasubject replication studies that demonstrate efficacy" (pp. 19-21). This rating was assigned due to the heterogeneous patient populations studied and the absence of control groups.

Whitehead and Drossman (1996) concluded that when pelvic nerve injuries impair anal sphincter contraction or sensory feedback from stretch receptors in the rectal wall, biofeedback can eliminate or reduce the frequency of incontinence by 90% for about 72% of patients. Most gastroenterologists consider biofeedback the treatment of choice in these cases. Biofeedback is also preferred for treating constipation due to a patient’s inability to relax pelvic floor muscles during elimination. Biofeedback also shows promise for treating rectal pain due to excessive pelvic floor muscle contraction.

Heymen, Jones, Ringel, Scarlett, and Whitehead (2001) estimated that biofeedback for fecal incontinence achieves a 67-74% success rate. They criticized the experimental design of several of the studies they reviewed.

Seymour (2002) concluded that the effectiveness of fecal incontinence biofeedback has been demonstrated for neurogenic and idiopathic anal incontinence, and incontinence related to disruption of anal sphincters. Fecal incontinence biofeedback reduced incontinence episodes 90% in more than 60% of patients. Electrical stimulation of the anal sphincter combined with biofeedback may result in greater symptom and pressure improvement than biofeedback alone.

Mahony and colleagues (2004) randomly assigned 60 symptomatic women diagnosed with postpartum fecal incontinence to 12 weekly sessions of intra-anal electromyographic biofeedback alone or combined with electrical stimulation of the anal sphincter. They also assigned these patients daily pelvic floor exercises. Fifty-four women completed treatment. Both groups achieved improved continence scores and squeeze anal pressures, while resting anal pressures did not change. Patients in both groups also reported improved quality of life. The addition of electrical stimulation did not improve therapeutic outcome.

Urinary incontinence is the involuntary loss of urine. This problem affects approximately 13 million Americans, mainly women. Three common types of incontinence are urge incontinence, stress incontinence, and mixed incontinence.

Urge incontinence involves involuntarily emptying the entire bladder and is produced by detrusor muscle overactivity due to detrusor myopathy (abnormal muscle condition), neuropathy (nerve damage), and both myopathy and neuropathy.

Stress incontinence is the involuntary loss of a variable amount of urine when intra-abdominal pressure increases. The problem in stress incontinence is the failure of the urethral sphincters to resist urinary flow. Possible stress incontinence causes include excessive urethral movement due to insufficient pelvic floor support and intrinsic sphincter deficiency.

Mixed incontinence is the involuntary loss of urine that results from stress and urge incontinence. The detrusor is overactive and the urinary sphincters are weak (Choe, 2002; Geurrero & Sinert, 2002; O'Shaughnessy, 2006).

About 13 million Americans may experience urinary incontinence. The prevalence of this disorder may range from 10-25% in females 15-64, and 1.5-5% in males (O'Shaughnessy, 2006).

The urinary bladder is located in the pelvic cavity. The bladder wall consists of three coats. The intermediate coat is the detrusor muscle, which is composed of three smooth muscle layers. The movement of urine from the urinary bladder to the urethral orifice is controlled by the involuntary internal urethral sphincter (smooth muscle) and voluntary external urethral sphincter (skeletal muscle).

Micturition (urine discharge) is produced by contraction of involuntary and voluntary muscles coordinated by the micturition center in spinal cord segments S2 and S3. When bladder volume exceeds 200-400 ml, the micturition center triggers the micturition reflex.

During the micturition reflex, the micturition center signals the detrusor muscle to contract and the internal urethral sphincter to relax, and blocks contraction of the external urethral sphincter, causing it to relax.

During early childhood, we learn to initiate or delay urination by learning to control the external urethral sphincter and pelvic floor muscles. (Choe, 2002; Geurrero & Sinert, 2002; O'Shaughnessy, 2002).

Clinicians use three strategies to treat urinary incontinence: reducing detrusor overactivity by monitoring the bladder using an inserted catheter, increasing the strength of pelvic floor muscles using SEMG sensors (vaginal or anal) or pressure sensors, and combining the previous methods while minimizing intra-abdominal pressure increases monitored by a rectal balloon (multimeasurement method).

Tries and Brubaker (1996) recommended the multimeasurement method because it reinforces “a more discriminate pelvic floor contraction” than single channel methods. The multimeasurement method achieved superior reductions in incontinence episodes from 75.9-82% in about 5 sessions, compared with 43-61% reductions with single-channel biofeedback in an average of 11 sessions.

Biofeedback training sessions use devices like the Thought Technology Ltd. MyoTrac 3 Continence Trainer and continence software, which displays pelvic floor and accessory muscle SEMG activity.


Biofeedback training in the clinic is supplemented by a home program that includes symptoms logs and pelvic muscle training exercises using devices like the Thought Technology Ltd. U-Control home continence trainer shown above.

Evidence-Based Practice in Biofeedback and Neurofeedback (2004) rates biofeedback for urinary incontinence in females at level 5 efficacy, efficacious and specific. Level 5 efficacy means: "The investigational treatment has been shown to be statistically superior to credible sham therapy, pill, or alternative bona fide treatment in at least two independent research settings" (p. 35).

Researchers have found that biofeedback for urinary incontinence in females is superior to no treatment, comparable or superior to alternative behavioral treatments like pelvic floor exercises, and superior to drugs like oxybutynin chloride, regardless of patient age. A stepped program that combines drug and behavioral treatments may be superior to an individual treatment.

Evidence-Based Practice in Biofeedback and Neurofeedback (2004) rates biofeedback for urinary incontinence in males at level 4 efficacy, efficacious. The criteria for level 4 efficacy include:"

  1. In a comparison with a no-treatment control group, alternative treatment group, or sham (placebo) control utilizing randomized assignment, the investigational treatment is shown to be statistically significantly superior to the control condition or the investigational treatment is equivalent to a treatment of established efficacy in a study with sufficient power to detect moderate differences, and
  2. The studies have been conducted with a population treated for a specific problem, for whom inclusion criteria are delineated in a reliable, operationally defined manner, and
  3. The study used valid and clearly specified outcome measures related to the problem being treated, and
  4. The data are subjected to appropriate data analysis, and
  5. The diagnostic and treatment variables and procedures are clearly defined in a manner that permits replication of the study by independent researchers, and
  6. The superiority or equivalence of the investigational treatment has been shown in at least two independent research settings" (p. 36).

Van Kampen et al. (2000)
reported that biofeedback for urinary incontinence following prostatectomy was superior to a no-treatment control. Floratos et al. (2002) showed that biofeedback for urinary incontinence was equivalent to pelvic floor exercises.

Evidence-Based Practice in Biofeedback and Neurofeedback (2004) rates biofeedback for urinary incontinence in children at level 2 efficacy, possibly efficacious. The criteria for level 2 efficacy include "At least one study of sufficient statistical power with well identified outcome measures, but lacking randomized assignment to a control condition internal to the study" (pp. 36-37). A level 2 rating was awarded due to lack of randomized clinical trials.

While studies of biofeedback continence training for children lack randomized assignment to experimental and control conditions, three studies showed improved continence in 80-90% of participants (Combs, Glassberg, Gerdes, & Horowitz, 1998; Hoekx, Wyndaele, & Vermandel, 1998; McKenna, Herndon, Connery, & Ferrer, 1999).

After removal of meniscus cartilage in the knee, a postmeniscectomy patient experiences weakness in the muscles that act on the leg. A knee joint is shown below with cartilage and tendons.


Acute meniscal tears are diagnosed in 61 of 100,000 persons in the United States. Males outnumber females 2.5 to 1. Meniscal injury shows the highest incidence in males 31-40 and females 11-20. The rate of this problem is 60% in patients above the age of 65 (Baker, 2004).

SEMG electrodes may be placed over the quadriceps femoris to assist practice of isometric or isotonic contractions to increase muscle strength. Initial electrode spacing should be wide due to weak muscle output and then narrowed to reduce crosstalk from co-contracting hamstring muscles.

The vastus lateralis and vastus medialis obliquus muscles are shown below on the left diagram above the knee.


Total knee arthroplasty (TKA) treats knee pain, deformity, and instability due to degeneration or inflammation by replacing the knee with a prosthesis. Pain due to severe arthritis is the primary indication for this procedure. Physical therapy is initiated soon after surgery and involves exercises which may be complemented by use of a continuous passive motion (CPM) device. Patients must usually achieve 90 degree knee flexion before discharge (Palmer & Cross, 2004).


Approximately 130,000 total knee replacement operations are annually performed in the United States. While osteoarthritic degeneration of the knee is seen in the radiographs of 40% of 40-year-olds, only half of these individuals are symptomatic (Palmer & Cross, 2004).

Kuiken, Amir, and Scheidt (2004) studied 14 asymptomatic controls and 11 patients following total knee arthroplasty (TKA), in which the knee joint was surgically replaced. A computerized biofeedback knee joint goniometer (CBG) provides patients and physicians with audiovisual feedback about knee joint angle. This information is crucial in retraining TKA patients to achieve a normal range-of-motion (ROM). The authors reported that CBG-angle measurements were highly correlated with manual clinician measurements between 0° and 100°. Most patients showed good acceptance of CBG. Auditory feedback motivated exercise more than visual feedback. There was slightly more ROM activity on days that that the device silently monitored patients than on the audiovisual feedback days.

Muscle-tendon transfer is a procedure that repositions a tendon so that an attached muscle can be reoriented and produce a new movement. This operation is used when there is permanent muscle injury or paralysis and is designed to replace or reconstruct a missing motor function (Higgs & Baumeister, 2005).

SEMG biofeedback is used to increase motor unit recruitment in re-educated muscles and reduce interference from antagonist muscles. Where SEMG measurements do not correspond to a change in position, as when the recording surface (wrist) is too small for electrodes or the muscle lies too deeply, positional feedback may be superior. For example, an electrogoniometer (shown below) places a potentiometer over two bones that form a joint and displays joint angle changes as changes in voltage.


Now that you have completed this module, locate the muscles discussed above in a muscle atlas.  Consider where two-channel SEMG assessment is indicated and why.

Baker, B. S. (2004). Meniscus injuries. eMedicine.

Basmajian, J. V. (Ed.). (1989). Biofeedback: Principles and practice for clinicians. New York: Williams & Wilkins.

Choe, J. M. (2002). Incontinence, urinary: Surgical therapies. eMedicine.

Combs, A. J., Glassberg, A. D., Gerdes, D., & Horowitz, M. (1998). Biofeedback therapy for children with dysfunctional voiding. Urology, 52(2), 312-315.

Cram, J. R., & associates (1990). Clinical EMG for surface recordings: Volume 2. Nevada City, CA: Clinical Resources.

Floratos, D. L., Sonke, G. S., Rapidou, C. A., Alivizatos, G. J., Deliveliotis, C., Constantinides, C. A., et al. (2002). Biofeedback vs. verbal feedback as learning tools for pelvic muscle exercises in the early management of urinary incontinence after radical prostatectomy. British Journal of Urology, International, 89(7), 714-719.

Geurrero, P., & Sinert, R. (2002). Urinary incontinence. eMedicine.

Gevirtz, R. (2003). The mind/muscle connection: A search for psychophysiological mechanisms of chronic muscle pain. Special  Address presented at the 34th AAPB annual convention at Jacksonville, Florida.

Hartje, J. (1997). Biofeedback: Basic neuromuscular intervention (module 3). Wheat Ridge: AAPB.

Heymen, S., Jones, K. R., Ringel, Y., Scarlett, Y., & Whitehead, W. E. (2001). Biofeedback treatment of fecal incontinence: A critical review. Diseases of the Colon and Rectum, 44(5), 728-736.

Higgs, P. E., & Baumeister, S. (2005). Hand, tendon transfers. eMedicine.

Hoekx, L., Wyndaele, J. J., & Vermandel, A. (1998). The role of bladder biofeedback in the treatment of children with refractory nocturnal enuresis associated with idiopathic detrusor instability and small bladder capacity. Journal of Urology, 160 (3 pt 1), 858-860.

Kuiken, T. A., Amir, H., & Scheidt, R. A. (2004). Computerized biofeedback knee goniometer: acceptance and effect on exercise behavior in post-total knee arthroplasty rehabilitation. Archives of Physical Medicine Rehabilitation, 85(6), 1026-1030.

McKenna, P. H., Herndon, C. D., Connery, S., & Ferrer, F. A. (1999). Pelvic floor muscle retraining for pediatric voiding dysfunction using interactive computer games. Journal of Urology, 162(3 pt 2), 1056-1063.

Mahony, R. T.,  Malone, P. A., Nalty, J., Behan, M., O'Connell, P. R., & O'Herlihy, C. (2004). Randomized clinical trial of intra-anal electromyographic biofeedback physiotherapy with intra-anal electromyographic biofeedback augmented with electrical stimulation of the anal sphincter in the early treatment of postpartum fecal incontinence. American Journal of Obstetrics and Gynecology, 191(3), 885-890.

Nelson, R., Norton, N., Cautley, E., & Furner, S. (1995). Community-based prevalence of anal incontinence. JAMA, 274(7), 559-561.

O'Shaughnessy, M. (2006). Incontinence, urinary: Comprehensive review of medical and surgical aspects. eMedicine.

Palmer, S. H., & Cross, M. J. (2004). Total knee athroplasty. eMedicine.

Saulny, S. S. (2005). Blepharospasm, benign essential. eMedicine.

M. S. Schwartz, & F. Andrasik (Eds.). (2003). Biofeedback: A practitioner's guide (3rd ed.). New York: The Guilford Press.

Seymour, S. D. (2002). Fecal incontinence. eMedicine.

Tortora, G. J., & Derrickson, B. H. (2006). Principles of anatomy and physiology (11th ed.). New York: John Wiley & Sons.

Tries, J., & Brubaker, L. (1996). Application of biofeedback in the treatment of urinary incontinence. Professional Psychology: Research and Practice, 27(6), 554-560.

Tries, J., Eisman, E., & Lowery, S. P. (1995). Fecal incontinence. In M. S. Schwartz (Ed.). (1995). Biofeedback: A practitioner's guide. New York: The Guilford Press.

Van Kampen, M. De Weerdt, W., Van Poppel, H., De Ridder, D., Feys, H., & Baert, L. (2000). Effect of pelvic floor re-education on duration and degree of incontinence after radical prostatectomy: A randomized controlled trial. Lancet, 355(9198), 98-102.

Whitehead, W. E., & Drossman, D. A. (1996). Biofeedback for disorders of elimination: Fecal incontinence and pelvic floor dyssynergia. Professional Psychology: Research and Practice, 27(3), 234-240.

Yucha, C. B., & Gilbert, C. D. (2004). Evidence-based practice in biofeedback and neurofeedback. Wheat Ridge: AAPB.