The Underwear That Changed How I Feel About Running on My Period

June 13, 2026

NIXI Body The Susie Black Leakproof Knicker showing the mid-rise VPL-free design with four-layer absorbent gusset holding up to 15ml suitable for periods bladder leaks and exercise

I have been running for about six years. Not competitively, just the kind of running that keeps me sane: three or four times a week, usually early morning, usually between five and ten kilometres. It is the part of my routine that I am most protective of and most reluctant to skip.

For most of those six years, I had been skipping runs on heavy period days. Not every period day, just the heavy ones, the days when the combination of products I was using never felt quite secure enough for the movement and impact of running. I had tried various combinations: tampon plus pad, tampon plus period underwear that was not quite absorbent enough, tampon plus hope. None of them gave me the confidence to run without the low-level anxiety that something was going to go wrong mid-run.

My name is Jess Hartley. I am a thirty-two-year-old physiotherapist from Manchester, and I had been accepting the skipped runs as an unavoidable feature of having a period. That turned out to be wrong.

The Discovery

A colleague mentioned NIXI Body period underwear at work in February. She had been using The Susie for about six months and had specifically recommended it for running, which is what caught my attention. I had tried period underwear before but had found it either too bulky to be comfortable under gym leggings or not absorbent enough to use without additional products on heavier days.

I found NIXI Body The Susie Black Leakproof Knicker at ALTOE. The spec addressed both of my previous objections. The four layers of discreet absorbent gusset hold up to 15ml, which is 2-3 tampons worth, which is enough for a medium to heavy period day with or without additional products. The mid-rise VPL-free design is specifically described as invisible under gym leggings and activewear, and as loved by runners and athletes. The 75% nylon, 25% elastane outer with a cotton lining and waterproof TPU layer is the construction that makes it both comfortable and genuinely leakproof.

At £18 it was a straightforward trial. I ordered it on a Wednesday. It arrived Friday.

NIXI Body The Susie Black Leakproof Knicker shown in activewear context demonstrating how the VPL-free mid-rise design sits invisibly under gym leggings with no visible panty line during exercise

The First Run

My period started on the Monday after it arrived. Tuesday was a heavy day. I put on The Susie, wore it alongside a tampon as I would normally, and went for my usual 7km morning run.

I ran without anxiety. That is the most accurate way to describe it. The low-level monitoring that I had been doing on heavy period days, the constant awareness of whether something was going wrong, was not there. The underwear felt secure throughout the run. The VPL-free design was genuinely invisible under my leggings. I got home, checked, and everything was fine.

NIXI Body The Susie Black Leakproof Knicker product features showing the four key benefits including the four-layer absorbent gusset holding up to 15ml the VPL-free design the washable reusable construction and the comfortable mid-rise waistband

I had not run on a heavy period day without anxiety in six years. The difference was immediate and significant in a way I had not quite anticipated.

Four Months On

I have not skipped a run due to my period in four months. I wear The Susie on every period day, heavy or light, with or without additional products depending on the day. The absorbency has been reliable throughout. The VPL-free design has been consistently invisible under leggings. The mid-rise waistband has not rolled or shifted during runs.

NIXI Body The Susie Black Leakproof Knicker absorbency guide showing the 15ml capacity equivalent to 2-3 tampons and the suitability for medium period days bladder leaks discharge and sweat during exercise

The washing instructions are straightforward: 30 or 40 degrees, no fabric conditioner, air dry. The air drying takes slightly longer than standard underwear due to the layers, which I had been warned about and which is a minor consideration rather than a problem. After four months of regular washing, the absorbency and the waterproof layer are performing exactly as they did on the first use.

NIXI Body The Susie Black Leakproof Knicker shown from the back on a model demonstrating the mid-rise fit the comfortable waistband and the discreet absorbent gusset design that provides leakproof protection during activity

I have bought two more pairs, which means I have three in rotation and always have a clean pair available during my period. The cost per pair at £18 is considerably less than the ongoing cost of the additional products I had been using, and the environmental benefit of washable reusable underwear over disposable products is meaningful.

NIXI Body The Susie Black Leakproof Knicker shown in a lifestyle context demonstrating the everyday wearability of the period underwear beyond exercise including its suitability for work and daily activities

Three friends who run have bought The Susie after I mentioned it. All three have reported the same experience: the anxiety that had been accompanying period day runs is gone, the design is genuinely invisible under leggings, and they have stopped skipping runs. One of them, who had been skipping runs for longer than I had, said it was the most practically useful thing she had bought in a year.

NIXI Body The Susie Black Leakproof Knicker shown in multiple colourway context demonstrating the award-winning design that has been recognised for combining leakproof performance with everyday comfort and activewear compatibility

NIXI Body The Susie Black Leakproof Knicker care and fabric guide showing the 75 percent nylon 25 percent elastane outer cotton lining waterproof TPU construction and the washing instructions for maintaining performance

The Verdict

If you run and you have been skipping runs on heavy period days because the combination of products you are using does not feel secure enough, try period underwear designed specifically for activity. The NIXI Body Susie is the right choice: the absorbency is genuine, the VPL-free design is genuinely invisible under leggings, the mid-rise fit stays in place during runs, and the washable construction makes it a better long-term option than disposable products. I have not skipped a run due to my period in four months. That is the result.

Find NIXI Body The Susie Black Leakproof Knicker at ALTOE. Listed in Latest Products, Apparel & Accessories, Clothing, Lingerie, and Women's Underpants.

Stop skipping the run. The right kit makes it possible.

— Jess Hartley, Manchester