Leaking when you run, jump, skip or land is stress incontinence under load: each impact pushes the bladder down against a pelvic floor that is not braced or not strong enough for that instant. It is the most common reason women quietly stop exercising, it happens to women who have never had children, and it usually improves with pelvic-floor physiotherapy. This page covers why impact is different from a sneeze, what runners and trampoliners actually do about it, and what to wear so a session does not end in a wet patch.
The forum threads tell the story: "Runners, any help with stress incontinence?", "Just wet myself whilst running", "Help: need running knickers and stress incontinence liners that don't chafe!!", "Is this the right place? Trampolining and pelvic floor (or lack of it)". And the confession underneath them all: "I feel like the more I ran the more I leaked. When I stopped, the problem stopped."
Why running and jumping leak when walking does not
Every landing sends a spike of pressure through the abdomen onto the bladder. Walking produces small spikes the pelvic floor absorbs without noticing. Running produces a spike every step, at two to three times body weight; a trampoline produces larger ones, on repeat, for twenty minutes. The pelvic floor has to contract a fraction of a second before each impact, hundreds of times, and it fatigues. That is why women leak at kilometre four and not kilometre one, and on the trampoline but not on a sneeze. Studies of elite trampolinists have found that most of them leak during training; nobody would call elite gymnasts weak.
Why do I leak when I run if I have never had kids?
Because impact exposes a pelvic floor that has never been trained, whether or not it has been through childbirth. High-impact sport, heavy lifting with a held breath, chronic coughing, constipation, hypermobility and a naturally weaker pelvic floor all produce it. Women in their twenties who run, do HIIT, ride horses or dance ask this question constantly. "I'm 24 and the incontinence pads get full within the first minute of exercise" is a real post. You are not an anomaly, and you are not too young.
I stopped drinking water before I ran
A lot of women do this, and it makes the next run worse. Concentrated urine irritates the bladder and increases urgency, and dehydration makes cramps and fatigue worse. Drink normally, empty just before you start, and manage the leak with the right pelvic-floor work and the right underwear rather than with thirst.
The tampon trick, and why it half works
"Wear a tampon during your run. Weird but it's true, it's a complete game changer." It is a genuine hack: a tampon sits behind the urethra and gives it something to press against, which is roughly what a pessary does properly. It is not what tampons are designed for, it does nothing for the pelvic floor, and it is a poor idea outside a period. If it helps you, mention it to a pelvic-health physiotherapist; there are devices made for exactly that job, and a physiotherapist can fit one.
What actually helps
- Pelvic-floor physiotherapy, first. A physiotherapist checks whether you are contracting the right muscles, whether the problem is weakness or tightness (a tight pelvic floor leaks too, and Kegels make it worse), and builds impact tolerance step by step: walk-run intervals, then longer runs. Most women improve.
- Brace before impact. Squeeze and lift the pelvic floor a moment before a jump or a landing. On a trampoline, that means on every bounce, which is why fatigue is the limit.
- Build back up gradually after a baby. Returning to running too early, before the pelvic floor has recovered, is the most common cause of postpartum running leaks. Physiotherapists generally advise a structured return rather than a date.
- Empty before you start, keep drinking, cut caffeine before a session if it triggers you.
- Treat constipation. A full bowel presses on the bladder and the pelvic floor.
What to wear
The honest job of underwear here is to catch the leak that gets through while the physiotherapy does its work, without chafing, showing under leggings or bunching mid-run. Pads and liners fail all three: they shift, they chafe, and a full pad "feels like a diaper" by kilometre five. A pair with the absorbent panel sewn in and a waterproof layer that runs to the leg edge keeps the leak inside the garment and off your leggings.
Our P14 leak-proof panty holds up to 100 ml in daytime use, has four layers with a wicking top layer built for a fast surge rather than a slow trickle, and is a high-waist panty from the outside; sizes XS to 4XL. For period days that coincide with a run, the SLK8036 boyshort does both jobs. Neither is built for a full bladder release, and a trampoline session that empties the bladder exceeds any washable underwear; the point is the repeated small leaks that add up over a session, which is what most women describe.
Three or four pairs cover a week of training days; the how-many-pairs guide has the arithmetic. Rinse cold after the session and wash without fabric softener, or the wicking layer stops working; see how to wash leak-proof underwear.
Why is my underwear wet after running?
Sweat, or a leak, and the smell tells you which when you get home. A urine smell and a patch concentrated at the front is a stress leak. Our why is my underwear wet page walks through the difference. If it is a leak, nothing on this page says stop running; the physiotherapists on the running forums say the opposite.
When to see a doctor
- Leaks that started suddenly or are getting worse quickly.
- Leaks with pain, burning, blood, or a fever.
- A feeling of heaviness, dragging or a bulge in the vagina, especially after running; that can be a prolapse and needs assessment before more impact.
- Leaks in the months after childbirth that are not improving.
Common questions
Why do I leak when I run?
Each landing sends a spike of pressure onto the bladder. If the pelvic floor is not braced or strong enough for that instant, a little urine escapes. Running repeats that hundreds of times and the muscles fatigue, which is why leaks appear later in a run. Pelvic-floor physiotherapy is the first-line fix.
Is it normal to pee a little when exercising?
It is common, including in women who have never had children and in elite athletes, and it is not something to accept as permanent. It usually improves with physiotherapy and a gradual build-up of impact.
Should I stop running if I leak?
Not necessarily. Physiotherapists generally advise assessment and a structured programme rather than stopping. The exception is a feeling of heaviness or a bulge, which should be checked before more impact.
What underwear is best for running with bladder leaks?
A pair with the absorbent panel sewn in, a wicking top layer for a fast surge, and a waterproof layer to the leg edge, so nothing shifts, chafes or shows. Our P14 holds up to 100 ml in daytime use.
Does the tampon trick work for running leaks?
It can reduce leaks by supporting the urethra, which is what a fitted pessary does properly. It does not treat the cause and is not what tampons are designed for. Ask a pelvic-health physiotherapist about a device made for the job.
Can I jump on a trampoline with bladder leaks?
Many women do, with pelvic-floor work and absorbent underwear for the small leaks that get through. A session that empties the bladder exceeds any washable underwear, and a feeling of heaviness afterwards should be checked before jumping again.
This page is general information, not medical advice. Leaks that are new, worsening or painful, or any sense of heaviness or a bulge, should be assessed by a doctor or pelvic-health physiotherapist.
Written by Laura Hopson, founder of Maven Nove. Last updated 10 September 2026.