Urinary incontinence (UI) is defined as the involuntary flow of urine and is a social and public health problem. Urinary incontinence not only leads to perineal rashes, pressure sores and urinary tract infections, but also causes embarrassment and negative self-perceptions. In incontinent groups, they experience reduced social interaction, poorer self-evaluation of health, low emotional and psychological status, sexual relationship disorders, reduced quality of life and depressive symptoms.
1.Types of urinary incontinence
There are three main types of urinary incontinence: stress incontinence, urge incontinence and mixed incontinence.
Stress incontinence is the involuntary flow of urine that occurs at work or during exertion, or when coughing and sneezing. During work and exertion, the intra-abdominal pressure increases and the urethral sphincter is unable to maintain a pressure higher than that of the bladder. Urinary overflow can also occur during daily activities such as lifting heavy objects, laughing, jumping, sneezing or coughing.
Urge incontinence refers to the leakage of urine on or immediately after the onset of the urge to urinate. During bladder filling, the bladder contracts abnormally, so the sensation of urination becomes more intense, making it difficult to ignore and eventually leading to the onset of leakage. Urge incontinence may be associated with overactive bladder disorder, which is characterized by frequent, urgent and nocturnal urination, with or without urge incontinence.
Mixed incontinence is associated with involuntary leakage with urgency and is also associated with exertion, work, sneezing or coughing.
2. Pelvic floor anatomy and mechanisms of incontinence
The mechanism of urinary incontinence is related to the structure of the pelvic floor. The pelvic floor is made up of transverse muscles arranged in a dome shape, which is usually considered a suspensory structure. The fascia and muscles of the pelvic floor support the bladder, uterus, and rectum. The deep pelvic floor muscles include the levator and sciatic caudalis muscles. During the bladder storage period, activation of the sympathetic nervous system increases the tension and contraction of the internal urethral sphincter thereby preventing leakage.
3.Pathophysiology of stress urinary incontinence
The main anatomical hypotheses for the pathogenesis of stress incontinence are as follows: loss of supporting structures, the “hammock hypothesis” and the neurological hypothesis.
In addition to the above three hypotheses related to urinary incontinence, there are some risk factors associated with the development of urinary incontinence, such as the number of births, age, decreased collagen volume and elasticity, race, obesity, smoking, chronic cough, respiratory disease, pelvic surgery, chronic constipation, and carbonated beverage intake.
There are also nonspecific risk factors such as pelvic organ prolapse, medications, fluid intake, fecal incontinence, and pelvic pain that can contribute to the development of stress urinary incontinence. Notably, pelvic symptoms associated with stress incontinence include diaphoretic incontinence, pelvic organ prolapse, constipation, sexual dysfunction, chronic pelvic pain, low back pain, and hip pain.
4.Treatment of stress urinary incontinence
In female patients with stress urinary incontinence, physical therapy options include physical therapy of the pelvic floor, lifestyle and behavioral therapy, and pharmacotherapy, and also patient education.
Pelvic floor physiotherapy
The most common treatment for stress urinary incontinence is pelvic floor muscle training (PFME), or specific strength training for the levator muscle. The theory behind this treatment is that strong contractions of the detrusor muscle improve urethral closure and increase support for the pelvic organs. If the contraction of the pelvic floor muscles is strong enough and timely, then the urethra can be compressed and the leakage interrupted.
Since the levator muscle is composed of both type I and type II muscle fibers, targeted plyometric training can affect the type II muscle fibers and thus assist the urethral sphincter in preventing urinary incontinence. Kegel training can be performed with verbal guidance from a therapist or under palpation to promote contraction of the levator muscle.PFME focuses on strength training and motor control coordination training for the muscles that make up the abdominal wall, resulting in stabilization of the lumbosacral muscles.
In women with stress urinary incontinence, the effectiveness of PFME training depends on the frequency and intensity of training. For example, previous studies have suggested that in women with mild to moderate stress incontinence, a program of 2 to 4 seconds of muscle contraction per session, with 15 repetitions for 1 set, and 3 sets of training per day for 8 weeks, significantly relieved the patient’s incontinence symptoms.
Knack or diagonal bracing techniques can also prevent urinary leakage during increased intra-abdominal pressure, and patients are generally instructed to contract the pelvic floor muscles prior to an increase in pressure (e.g., before sneezing) to prevent leakage. However, the rationale for these interventions (PFME or behavioral therapy applying Knack principles) in patients with stress urinary incontinence is not well understood. And because the maximum efficacy of plyometric training usually peaks 5 months after training, the slightly shorter duration of training studied is also a shortcoming.
In a Cochrane search for PFME, treatment was more effective when women were trained for at least 3 months.
Borello-France et al. compared the effectiveness of PFME training in two different positions, such as in an upright position such as sitting or standing, and in a supine position. The results suggest that posture is not an important influence in PFME training. However, the authors of this paper believe that further studies are needed to further validate the effect of training position on the efficacy of PFME.
In clinical practice, physiotherapy for the pelvic floor muscles generally follows the following sequence, starting with training in a gravity-eliminating position, followed by training in an anti-gravity position, and finally training on an unstable support plane (e.g., application of a Swiss ball). It is also important to keep in mind that the closer the motor task is to the functional task, the greater the benefit to the patient.
PFME combined with biofeedback therapy
Biofeedback or palpation can clarify whether the patient’s muscle contractions are correct or not. In women, feedback can be obtained by placing small electrode pads around the anus or by applying electrodes built into the vagina. The application of biofeedback techniques allows the patient to feel the muscle output immediately during the training.
According to previous information in the literature, PFME combined with biofeedback is not as effective as PFME alone. However, PFME combined with biofeedback may be an effective and acceptable treatment option. A practical treatment strategy is to combine biofeedback therapy at the start of PFME training in patients who have difficulty understanding how to contract or are unable to contract the pelvic floor muscles.
PFME combined with electrical stimulation
Physical therapists can also use electrical stimulation therapy to reduce the incidence of incontinence. The goal of electrical stimulation is to increase muscle volume, normalize reflex activity in the lower urinary tract, and improve circulation to the muscles and capillary system. Stimulation of the pubic nerves can improve urethral closure by activating the pelvic floor muscles.
A recent meta-analysis noted that the efficacy of electrical stimulation was comparable to that of sham stimulation or PFME in terms of improvement in urinary incontinence symptoms. However, electrical stimulation may be preferred in patients who are initially unable to contract the pelvic floor muscles on their own.
Preventive role of pelvic floor muscle training
There are no studies on the use of pelvic floor muscle training as a preventive treatment for stress urinary incontinence. In theory, strengthening the pelvic floor muscles with specific training can prevent stress incontinence and pelvic organ prolapse. If the pelvic floor has a certain strength, then muscle contraction has the potential to counteract the increase in abdominal pressure during physical activity.
Previous studies have focused on the preventive effect of PFME treatment on urinary incontinence at the time of pregnancy or after delivery. The researchers found that in women who did not have symptoms of incontinence, their pelvic floor muscle strength was stronger than that of incontinent women. The other two studies suggested that PFME training at the time of pregnancy or after delivery had no preventive effect. However, it is important to note that the strength of the evidence from these two studies is weak because their training programs consisted of only one session with a midwife or physiotherapist, with no supervision or guidance for subsequent sessions.
Barriers to successful implementation of physiotherapy
In general, female patients with stress urinary incontinence receive physical therapy once a week for 4 to 8 weeks. Home treatment combined with physical therapy is an effective treatment option for urinary incontinence. In addition, factors such as the patient’s education, activity level, number of births, smoking status, type of birth and pelvic pain may affect the patient’s ability to properly complete PFME.