I've seen a lot of health professionals over the past couple of years, and most of the appointments have been to do with running. No, that's not ammunition for people who moan that running is bad for you. It's because I started running at 41 after 15 years or so of a typical modern sedentary lifestyle, leaving me with weak gluteal muscles, a sagging pelvis and, consequently, excessive impact and problems on my right side. I've seen my GP, physios, masseurs, podiatrists. I've had acupuncture that taught me how extraordinarily powerful a token needle twiddle can be. But there is another issue I've suffered from since I began running, and it's an issue that dare not speak its name: sometimes when I run, I pee. While running.

You've heard of runners' trots. There are plenty of pictures of elite athletes unable to control their bowels, guts and periods (though, unlike one recent summing up of top marathon moments, I don't think the episode where Paula Radcliffe had to stop and publicly go to the toilet was one of them. I think her world record was). Maybe the reason there aren't so many videos showing runners voiding their bladders is because it's harder to see urine on TV. But I'm sure it happens more than is acknowledged. I can guess that from the massive queues at the ladies' toilets before every race, or from the way that female runners look anxiously at their watch in the half hour before the race starts, then dash to the toilet. I'm pretty sure I'm not the only woman before a race saying silently: 'Shall I go? No, I'll hold it. No, I'd better go."

I know it happens from discussing it with my female club mates. I know it happens from running forums online. And I know it happens because it happens to me. I am 44 years old, and so is my bladder. I haven't got the excuse of having had children – childbirth notoriously weakens the pelvic floor, particularly if forceps were involved – but I am a writer and my decades of sedentary lifestyle haven't only debilitated my glutes, but my pelvic floor, too.

I don't remember the first time it happened. I just know that I began to carry wet wipes and clean trousers to change into after a run, just in case. I've had emergency changing sessions in countless pub toilets. I've had to pee in the open, on roadsides or in bushes, and cursed the high-visibility neon orange jacket I run in, which is great for my safety but not for camouflage. Every pair of running tights and shorts I own is black, though I make up for it with garishness everywhere else. (And while I'm on the subject: running designers, how about some patterns?)

From forums, I know that some women wear Tena pads or nappies when they run. That's dedication, but it can't be comfortable. I preferred to try to fix it. I know I can because I've been doing more Pilates and pelvic-strengthening exercises to sort out my skewed running style, and the peeing-and-running has got much rarer. But I would like it to disappear for good, so I went to my GP, Dr Gemma Ashwell. She has done an ultramarathon and is sympathetic to running-related ailments – as every GP should be, if they do a cost benefit analysis and realise how much you're improving your health by running, thus not costing the NHS, and that the odd hip niggle or weak pelvic floor is a small price to pay.

She referred me to an incontinence clinic. I found this ironic, as I've written a book about sanitation and bodily excreta, and once gave a lecture to a hall full of NHS incontinence nurses. I wish I'd been a runner then, and got a hallful of free advice. Incontinence is a huge and unspoken issue. It can be desperate for many elderly people, some of whom stay home – on what is called a "bladder leash" – for fear of not being able to find a toilet in good time when they leave the house.

There are three types of incontinence, Ashwell told me: stress, urge and mixed. Stress urinary incontinence is the most frequent form. It's defined by the International Continence Society as "involuntary leakage on effort or exertion or on sneezing or coughing". In her experience, "it is surprisingly common in women. Studies have shown the prevalence [in men] to be very low, ie less than 1%." She has never had a male patient with SUI.

Is it worse among runners? There isn't much research on it, though Ashwell sent me a 2011 paper that found 26.3% of female fitness instructors reported urinary incontinence. The researchers concluded that their research suggested "a higher prevalence in young women who practice high-impact sports, specifically those involving jumping". (Running, of course, is constant jumping.) A 1990 US study found 38% of female runners reported stress incontinence. Their average age was 38, but even in younger, nulliparous women (a lovely word that means a woman who hasn't given birth), the rate was 28%.

So where are these women? It is obviously not just me. In Ashwell's experience, many women try to cope with SUI themselves. "Those few that we do see are likely to be the tip of the iceberg."

It is true that it took me a few years to get to my doctors' surgery with my SUI. My reluctance was bizarre, as I'm not embarrassed by it. You can't write a book about toilets and be embarrassed about peeing. Also, I'm delighted that my body is strong enough to run at all, and for miles. That is more important to me than the fact that in a contest between weak pelvic floor muscles and a constant pounding motion for great distances, the muscles sometimes lose. "It's a shame that women may be suffering in silence," says Ashwell. "I hope that increased awareness of it will encourage women to get help when they need it."

Luckily my pelvic floor, as the incontinence nurse discovered with the aid of some surgical gloves and internal clutching, isn't a hopeless cause, just lazy. It can be strengthened, along with my core, knees and glutes. She gave me daily exercises that I'm doing as I write this (she did say they could be done anywhere) and expects rapid improvement. And the wet wipes can be kept for cross-country races, where they will never be superfluous.