Can you exercise on your period?
Yes, and the NHS suggests gentle exercise as one of the things that can ease period pain, alongside heat, a warm bath, massage and painkillers such as paracetamol or ibuprofen. There’s no NHS guidance telling anyone to avoid sport during a period.
Wanting to is a different question, and it’s fine to drop the intensity on the days you feel rough. A walk, a swim or a yoga class counts. Brand A’s exercise advice says the same: move if it helps, ease off if it doesn’t.
The one caveat comes from the NHS heavy periods page, which lists periods that stop you doing daily activities such as exercise among the signs of heavy bleeding to raise with a GP. If your flow is what keeps you off the track rather than cramps or tiredness, our heavy flow guide sets out the rest of those signs.
Does exercise help period cramps?
Yes, probably, though the evidence is weaker than the headlines suggest. A 2019 Cochrane review of 12 studies covering 854 women found that exercise may substantially reduce period pain compared with doing nothing, by around 25 points on a 100-point pain scale. Both low-intensity exercise such as yoga and high-intensity exercise such as aerobics helped, and most of the studies used 45 to 60 minute sessions at least three times a week.
The reviewers rated the certainty of that evidence low to very low, so take it as encouragement rather than proof. It does mean that staying active across your cycle, not just exercising on the day your cramps hit, is the pattern that showed results.
Can you wear period pants for sport?
Yes, period pants are built for movement, which is why runners, gym-goers and cyclists often prefer them to pads that bunch or liners that peel off sweaty skin. Nothing moves against you, there’s no string, and no edge to rub. Annahitah describes its pants as made to support you through all types of exercise.
Independent testers back that up. The Stylist writer behind its exercise piece has run 30 km in period pants and found them as comfortable as ordinary running knickers, adding that liners wouldn’t stick to sweaty underwear anyway; the Fiona Outdoors review of a seamless running pair found that because nothing shifts, there’s less chafing than with a towel. Women’s Running’s testers judge pants on four things: chafe-free wear, sweat-wicking fabric, flat seams and no bulk.
| What matters for sport | Why | What to look for |
|---|---|---|
| Nothing visible under leggings | Lines show through thin fabric | Seamless or g-string styles |
| No chafing | Stitched edges rub when you sweat | Seamless or flat-seamed edges, snug fit |
| Sweat handling | Cotton holds sweat and stays damp | A wicking top layer |
| Stays put | Movement shifts pads and liners | A fitted waistband, no gaping at the leg |
| Enough capacity | Sweat and blood share the same layers | Your flow level for the day, one up for long sessions |
Which absorbency do you need for a workout?
Match the pants to your flow on that day, not to the workout, then go up a level for anything long. A 45-minute gym session on day four of your period needs the same Light or Medium pair you’d wear to the office. A long run on day two needs your heaviest.
The reason to size up for long sessions is capacity sharing. Period pants wick sweat into the same absorbent layers that hold blood, so on a hot two-hour run you’re asking one pair to do two jobs. Brand B’s sport advice is High Waist Heavy for high-intensity training on heavy days; Annahitah’s equivalent would be a Super Heavy such as Odessa, which is seamless and in the Sweat Control collection as well as the Super Heavy one.
For the gym on a light day, Annahitah’s Light styles (the Venus, Nirvana and Eden g-strings) do the job, and the brand says the same styles also cater for sweat when you’re not on your period.
Which styles disappear under leggings?
Seamless briefs and g-strings leave no lines under leggings, which is why they’re the two cuts sold as gym pants. Women’s Running’s buying guide names flat or absent seams as the thing that avoids both visible lines and chafing, and the Stylist writer credits no-VPL styles with the confidence to cycle to the gym in the first place.
Annahitah’s Sweat Control collection is built around this: Odessa, Venus, Nirvana, Luna and Eden, described as discreet and seamless under tight sportswear. Nirvana and Venus are the two g-strings the brand sells as invisible under tight gym clothes.
The trade-off is absorbency. G-strings are Light only, because the gusset is too short to hold more, so they suit light days and the sweat-only days between periods. For a heavy day under leggings, a seamless high-waist such as Odessa gives you the no-lines finish at Super Heavy capacity. Both routes are in the seamless period pants collection, which spans all four absorbencies, and the lighter option on its own is the invisible gym thongs collection.
One thing to check: the highest-waisted pants can peek above low-rise leggings. Luna, a seamless Medium high-waist with sheer side panels, is the lighter and stretchier of the two high-waisted seamless styles, so try it under a lower waistband.
A fit for your flow.
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Find your pair Explore styles, flow ratings & sizesDo period pants chafe when running?
No, a snug seamless pair is less likely to chafe than a pad, because nothing moves against your skin and there’s no adhesive edge or wing to catch. The chafing risk with pants comes from stitched seams at the leg or waist, a loose fit that lets fabric rub, or a cotton gusset that stays wet.
Three things reduce it:
- Edges with no stitched seam, which is what “seamless” means in practice, or at least flat seams.
- A size that sits flat without digging in. Annahitah’s sizes run generous, so pick the smaller if you’re between two.
- A wicking fabric. Women’s Running notes that cotton holds sweat and can chafe. Annahitah’s seamless styles such as Odessa, Nirvana and Luna are nylon and elastane blends, while the organic cotton Venus and Eden thongs suit shorter or cooler sessions.
Fiona Outdoors’ review of a seamless running pair found the gusset felt bulky at first but settled, which is a fair warning: the first run in period pants feels different from the second.
Do period pants handle sweat as well as blood?
Yes, the wicking top layer pulls sweat away from your skin as it does blood, but both end up in the same absorbent core, so a long sweaty run eats into capacity you may want for flow. On a short gym session this doesn’t matter. On a long run on a heavy day, it does.
Annahitah’s four-layer construction is an outer moisture-wicking layer with absorbent, breathable layers inside, and the brand sells its Light styles for sweat alone when you’re not on your period. The Sweat Control collection (Odessa, Venus, Nirvana, Luna, Eden) is the brand’s answer to visible sweat under gym clothes.
Practical rule: on a heavy day, treat a run of over an hour as a reason to go up a level or carry a spare in your kit bag.
Can you swim in period pants?
No, ordinary period pants don’t work in water, and Annahitah doesn’t sell swimwear yet. Brand A’s support page says plainly that its underwear isn’t designed for swimming because the fabrics aren’t made to be worn in water. The absorbent layers soak up pool water, leaving nothing for your flow, and the leak-proof layer can’t tell the difference.
A few related facts from Brand C’s piece on periods and water: water pressure can slow flow while you’re submerged, but the period doesn’t stop; a disposable pad absorbs water and becomes useless in the same way; and competition rules bar extra items under racing swimwear. If you swim on your period, the choices are a tampon, a cup or dedicated period swimwear, which several UK brands make.
Annahitah’s FAQ answer to “Do you offer swimwear?” is “Watch this space”, so that may change. For now, its pants are for dry land.
What about PE at school?
A Medium or Heavy pair worn from the morning covers a PE lesson without a changing-room swap, which is the main thing teenagers worry about. Brand B’s school advice is a bikini cut for PE and a high-leg style for leotards; Annahitah’s Valentina, the organic cotton brief sold as its signature teenage style, goes down to XXXS and is described on its page as great for sporty girls on the go.
Stylist quotes sports scientist Dr Georgie Bruinvels saying fear of leaking is one of the main reasons teenage girls drop out of sport during puberty. Pants that don’t move go some way to answering that.
How do you wash period pants after a sweaty session?
Rinse them in cold water as soon as you get home, then wash on a gentle 30°C cycle with your darks, no softener and no bleach. That’s Annahitah’s standard routine and it applies just the same after a run as after a normal day; the cold rinse clears sweat and blood before either sets.
Don’t leave a sweaty pair balled up in a gym bag overnight. If you’re changing after training, the washable organic cotton Eco-bag that comes with every Annahitah order is made for carrying the used pair home, and the bag itself washes at 30 or 40 degrees. Hang the pants to dry rather than tumbling if you can.
