While both the slow-twitch and fast-twitch muscles lose strength as the body ages, the fast-twitch muscle fibers do so more readily. The slow-twitch muscles that make the pelvic floor a center of endurance and support tend to keep their power and function longer—unless there is trauma or injury. In a sense, the power to endure remains, while the power to perform some of the pelvic floor's key functions can diminish.
That's natural. As we get older, our powers diminish. That's why it's so important to stay as fit as we can for as long as we can; physical strength and vigor are the best defense against the aging process.
That's certainly true where the pelvic floor muscles are concerned. It's no exaggeration to say that a healthy pelvic core is a major component of a healthy you. For that reason, it's important to pay attention to any pelvic pain or disorder; it could be a signal that something may be wrong. And unfortunately, lots of things can go wrong.
Of course, anytime you have a mechanism as highly complex as the pelvic floor, with all those muscles, nerves, tissues, and ligaments holding all those organs and attached to all that bone, it's prone to things going wrong. Basically, however, there are four root causes of pelvic floor disorders: inflammation, infection, trauma, and a range of what we might term "mechanical" muscular conditions—and any number of contributing factors that set the causes in motion.
Any kind of chronic inflammatory condition in any of the pelvic organs can originate a disorder.
So can any kind of infection: urinary tract infection, yeast infection, bacterial infection, or a major disease that affects the area.
Certainly, an injury from an accident or fall can cause dysfunction. Surgery—a hysterectomy, prostatectomy, or Caesarean section—can leave the muscles weak or injured. And physical or sexual abuse may also produce harmful trauma.
But it's equally possible that an individual's pelvic floor disorder has been caused by simple weakness in the trunk and pelvic stabilizers. Or maybe the person's spine and pelvis are misaligned. The individual may simply have been born with these conditions; it's not uncommon to inherit a weak trunk or a spinal misalignment. Or the conditions could be a result of poor posture, excessive strain from heavy lifting or other physical activities, or working at a repetitive-motion job. It is possible that you are using the pelvic floor muscles incorrectly, resulting in incoordination of the muscles. All can overload and/or shorten the pelvic floor muscles. Such stress weakens the muscles and decreases their range of motion.
Moreover, it doesn't take much to throw a monkey wrench into the works and kick off a disorder in the pelvic floor. Something as common as childbirth can do it. So can wearing clothing that is too tight, sliding too hard into third base at the Fourth of July softball game, using the wrong over-the-counter treatment for a yeast infection, or even playing a wind instrument. Any or all of these triggering factors could lead to a spasm or weakness or impairment of the muscles, producing dysfunctions ranging from debilitating pain to irritable bowel syndrome to skin disorders to erectile dysfunction and/or lowered libido.