Yes, your sphincter muscles do weaken with age. This is a normal part of aging, driven by gradual muscle loss, nerve changes, and shifts in connective tissue. The anal sphincter is the one most people are asking about, and the data is clear: resting anal pressure in women drops from an average of 88 mmHg before age 50 to about 63 mmHg after 50, roughly a 28% decline. That drop reflects real structural changes in the muscle, not just a vague slowing down.
What Actually Changes in the Muscle
Your anal sphincter is really two muscles working together. The internal sphincter is smooth muscle that stays contracted automatically, keeping things closed without any conscious effort. The external sphincter is skeletal muscle you can voluntarily squeeze. Both deteriorate with age, but in slightly different ways.
Animal studies examining aged sphincter tissue found that muscle content dropped from about 70% of the tissue in young subjects to 52% in old ones. The missing muscle gets replaced by connective tissue and collagen, a process called fibrosis. Think of it like a rubber band slowly being replaced by string: it loses its elasticity and can’t generate the same force. Researchers have identified specific proteins involved in both the muscle wasting and the scarring process, and both ramp up significantly with age.
This same pattern plays out in your urethral sphincter, which controls urine flow. A cadaver study of women aged 15 to 80 found that the urethra loses about 2% of its muscle fibers per year across a lifetime. That’s roughly 364 fibers disappearing annually. The individual fibers don’t shrink, they just vanish entirely, leaving fewer and fewer to do the job.
Nerve Signals Slow Down Too
Muscle weakness is only part of the story. The pudendal nerve, which carries signals from your spinal cord to your pelvic floor and sphincters, conducts more slowly as you get older. Studies measuring how fast this nerve fires found a clear positive correlation between age and signal delay. Participants over 50 had noticeably slower conduction times than younger adults. When the nerve signal arrives late or weakened, even healthy muscle can’t respond as quickly or forcefully, which matters most during sudden pressure changes like coughing, sneezing, or laughing.
Hormones Play a Role, Especially After Menopause
Estrogen receptors have been found directly in anal sphincter tissue, which means the hormone actively supports sphincter health. After menopause, when estrogen levels drop sharply, the effects can be significant. Animal studies show that removing the ovaries (which eliminates estrogen production) leads to a measurable reduction in the cross-sectional area of the anal sphincter’s striated muscle. This parallels the well-known effects of estrogen loss on vaginal tissue, bladder function, and other pelvic structures.
Whether estrogen replacement helps is less clear. Some small studies found that estrogen therapy improved internal sphincter resting pressure, possibly by altering collagen and elastic content in the pelvic floor. But a large prospective study found the opposite: current and past estrogen use was associated with more bowel leakage, possibly because estrogen loosens connective tissue in the internal sphincter. The relationship is genuinely complicated, and the research hasn’t settled it.
It’s Part of Whole-Body Muscle Loss
Sarcopenia, the age-related loss of skeletal muscle throughout your body, doesn’t spare the pelvic floor. The same process that makes it harder to open jars or climb stairs in your 70s is happening to the muscles that keep you continent. Fast-twitch muscle fibers, the ones responsible for quick, forceful contractions like clamping down when you feel urgency, are disproportionately affected. Both their size and number decline, which is why the “squeeze” component of sphincter function tends to weaken alongside grip strength and leg power.
Internal sphincter changes show up differently on pressure testing. Resting tone, the passive squeeze your internal sphincter maintains all day, drops significantly with age. But maximum voluntary squeeze pressure (the hardest you can clamp down) stays relatively stable longer. In one study of healthy women, squeeze pressure barely changed between younger and older groups (167 vs. 162 mmHg), while resting pressure fell by nearly 30%. This means the background, automatic tightness fades first, which is why age-related leakage often starts with minor soiling or difficulty holding gas rather than complete loss of control.
How Common Incontinence Becomes
Fecal incontinence affects about 2.6% of adults in their 20s. By age 70 and older, that number climbs to 15.3%, a roughly sixfold increase. That doesn’t mean most older adults experience it, but it does mean it becomes far more common. The risk factors stack up over a lifetime: childbirth injuries, chronic straining, surgeries, neurological conditions, and the baseline muscle and nerve deterioration that happens to everyone.
Your Esophageal Sphincter Ages Too
The sphincter at the bottom of your esophagus, which keeps stomach acid from flowing upward, also weakens with age. Older adults are more prone to acid reflux partly because this sphincter loses pressure over time. Medications commonly taken by older adults (blood pressure drugs, certain pain relievers) can reduce this pressure further. A higher frequency of hiatal hernia, slower esophageal contractions, and reduced saliva production compound the problem. This is why GERD becomes increasingly common in later decades.
Pelvic Floor Training Still Works
The most effective thing you can do is strengthen the muscles you still have. Pelvic floor muscle training, often called Kegel exercises, achieves 56% to 75% success rates for urinary incontinence, and the principles apply to anal sphincter function as well. These exercises target the external sphincter and the surrounding pelvic floor, building the voluntary squeeze that compensates for declining resting tone.
Consistency matters more than intensity. Studies in older women have confirmed measurable improvement in incontinence symptoms with regular pelvic floor training compared to no exercise. Biofeedback, where a sensor gives you real-time feedback on whether you’re contracting the right muscles, can help if you’re unsure you’re doing the exercises correctly. Staying physically active overall also helps slow sarcopenia, which indirectly supports pelvic floor strength. Maintaining a healthy weight reduces chronic downward pressure on the pelvic floor, and avoiding habitual straining during bowel movements protects both the muscles and the pudendal nerve from cumulative damage.