Our pick for the gym
Squat deep.
Nothing rides up.
Flissie women's bamboo boxer shorts are buttery soft and breathable, with a 6 inch leg that stays put through squats, lunges and classes, so your thighs glide instead of rub. Every size from UK 8 to 30, at one price.
4.7 out of 5 from 336 reviews
Choose my pair£13.50 a pair, or £11.50 a pair in a 10 pack. Free UK delivery. 60 Day Wear Test.
This guide compares gym underwear for women from Flissie, Runderwear, Boody and Step One on fabric, leg length, price and returns, so you know what to wear under leggings and shorts. Updated 10 November 2026: prices and specifications checked on each brand's own UK website on 8 October 2026.
At a glance
Gym underwear for women: the quick answer
For most gym sessions, a longer leg in a breathable fabric beats a brief. It puts a smooth layer between your thighs, it does not cut across your hip under a waistband, and it is less likely to ride into a wedgie the moment you squat.
- Our pick for classes, weights and walking: Flissie women's bamboo boxer shorts (we make them): buttery soft, breathable bamboo viscose with a 6 inch leg that stays put through squats and lunges, and a wide flat waistband that does not dig in, in every size from UK 8 to 30 at one price, £13.50 a pair or £11.50 a pair in a 10 pack, with a 60 day guarantee: full refund, worn or not.
- Hard cardio and running: Runderwear's 8 inch Women's Running Long Boxer, £23, in a recycled polyamide that dries faster, with a 90 day chafe-free guarantee.
- No visible line under fitted leggings: a seamfree brief such as Boody's Boyleg Briefs, £13, or Runderwear's seamless running brief, £18.
- The lowest price in bamboo viscose: Step One's Women's Body Shorts, £15, with most colours at £9 in its sale.
Prices checked on each brand's own UK website on 8 October 2026. Prices change often.
Three things decide whether it works:
- Leg length. Under 6 inches and it will not reach where thighs touch
- The right size. These work through skin contact, so sizing up beats sizing down
- Fabric. Anything that holds damp against you is worse than anything that moves it
Rated 4.7 out of 5 from 336 reviews (Judge.me, 10 November 2026)
"Perfect anti-chafe shorts! Really soft, light weight boxer shorts, they come to a good length to prevent chafe and are a lot cooler than my sports shorts"
Verified buyer, United Kingdom, April 2026
"These boxers are brilliant as the leg doesn't ride up and nothing digs in."
Val, United Kingdom, verified review, December 2025
"I have now bought this style pants from 4 suppliers and these are by far the best. Extraordinarily comfortable, they don't ride up and fit so well...love them."
Verified buyer, United Kingdom, April 2026
"They never rolled up under my trousers and the waist band was unnoticeable"
P.O., United Kingdom, review, January 2023
"The material is very lightweight and breathable, and the sizing/fit is perfect. Love the colours!"
Amalie, United Kingdom, verified buyer, August 2026
"Fabulous once I got the right size!"
Marian, United Kingdom, verified buyer, May 2026
Some reviewers earned a reward towards a future purchase.
Try them for 60 days
The 60 Day Wear Test
Wear them for 60 days. Under dresses, on long walks, through the wash. If they ride up, rub or roll, send them back for a full refund, worn or not.
- 10 pairs of Flissie women's bamboo boxer shorts in your colours and sizes (£135 at the single price)
- Free UK delivery
- Free size swap on your whole first order, as long as you try one pair and send the rest back unopened
- The 60 Day Wear Test: a full refund, worn or not
£11.50 a pair in a 10 pack
1 pair £13.504 pairs £546 pairs £7510 pairs £115
Start my Wear Test60 day guarantee from purchase: full refund, worn or not (return postage at your cost).
Why you can trust this guide
★★★★★ 4.7 out of 5 from 336 reviews of Flissie women's bamboo boxer shorts, and about 2,500 customers since 2021.
- Who wrote it: Phillippa and Matthew, the founders of Flissie. We have designed and sold women's boxer shorts from Derbyshire since 2021.
- Why Flissie is here: we make Flissie women's bamboo boxer shorts, and customers wear them for classes, weights, walking and marathon training, with a 6 inch leg that stays put in every size from UK 8 to 30.
- No paid placements: no brand paid to be included.
- How we compared: fabric, leg length, price and returns, from each brand's own UK website on 8 October 2026.
"Ridiculously comfortable and easy to wear" Tricia, United Kingdom, verified buyer, April 2026 (reviewer earned a reward for a future purchase)
The options, compared
The brands people weigh up for the gym, with the specifications each publishes. Ours is first and marked; the rest follow. Checked on each brand's own UK website on 8 October 2026.
| Fabric | Longest leg | Price | Best for | If you have worn them | |
|---|---|---|---|---|---|
| Flissie women's bamboo boxer shorts (ours, our pick) | 95% bamboo viscose, 5% elastane | 6 or 9 inch | £13.50, or £11.50 a pair in a 10 pack | Classes, weights, walking, hot rooms | 60 days, full refund, worn or not; free size swap on your whole first order, as long as you try one pair and send the rest back unopened |
| Runderwear Women's Running Long Boxer | 92% recycled polyamide, 8% recycled elastane | 8 inch | £23; running brief £18 | Hard cardio and running | No returns once tried on, but a 90 day chafe-free guarantee |
| Boody Boyleg Briefs and Seamfree Undershort | 79% viscose from bamboo, 15% nylon, 6% elastane | 6 inch undershort | Boyleg £13; undershort £18 | Low-sweat sessions, no visible line | Comfort Guarantee on your first single pair only |
| Step One Women's Body Shorts | 95% bamboo viscose, 5% spandex | Not published | £15; most colours £9 in its sale | Everyday, budget | 30 day first pair guarantee; sale items cannot be refunded |
| Sports brands | Polyester and nylon blends | Varies widely | Varies | High-output training | Varies |
On a phone, swipe the table sideways to see every column.
Flissie women's bamboo boxer shorts (ours, our pick)
Best for: classes, weights, walking and hot rooms, with a 6 inch leg, in UK 8 to 30
| Price | £13.50 a pair, or £11.50 a pair in a 10 pack, the same in every size. Free UK delivery. |
|---|---|
| What you get | 95% bamboo viscose and 5% elastane, buttery soft and breathable, seamless at the back and sides with a flat front seam that does not dig or rub, a wide flat waistband, and a 6 inch leg in all 8 colours or a 9 inch in black and pine green. |
| Pros | A published leg length that reaches where thighs touch and stays put when you squat, in a buttery soft fabric that breathes rather than traps heat. |
| Good to know | Built for classes, weights, walking and hot rooms; for a long, hard summer run, a technical synthetic dries faster. Seamless at the back and sides, with one flat front seam. |
| Reviews | 4.7 out of 5 from 336 reviews (Judge.me, 10 November 2026). |
| Guarantee | 60 days from purchase: full refund, worn or not (return postage at your cost). Free size swap on your whole first order, as long as you try one pair and send the rest back unopened. |
Why it is our pick for the gym: a published 6 or 9 inch leg (the 9 inch is the longest in this table) that stays put through squats and lunges, in a buttery soft fabric that breathes rather than traps heat, at one price in every size from UK 8 to 30. For classes, weights, walking and hot rooms, start with the 6 inch.
Shown in Sage green, 6 inch leg
Also in black, pine green, taupe white and chocolate brown. The 9 inch leg comes in black and pine green. Pictured: Flissie women's bamboo boxer shorts (we make them).
See the 6 inch legWrong size? We swap your whole first order free, as long as you try one pair and send the rest back unopened.
Runderwear Women's Running Long Boxer
Best for: hard cardio and running
| Price | £23 for the 8 inch long boxer, or £18 for the seamless running brief (8 October 2026). |
|---|---|
| What you get | An 8 inch long boxer in 92% recycled polyamide and 8% recycled elastane, 360 degree seamless, with silicone grippers around the leg hems, S to XL. |
| Pros | Dries faster than any natural fibre, and a 90 day chafe-free guarantee: Runderwear refunds you if a pair makes you chafe. 4.8 out of 5 from 197 reviews. |
| Cons | Fully synthetic, sizes stop at XL, and outside that guarantee it does not accept returns on underwear that has been tried on. |
Runderwear is the specialist and it shows. 360 degree seamless construction, flatlock edging, silicone grippers around the leg hems to stop them travelling, and a recycled polyamide that dries faster than anything natural. If you run or do hard cardio, they are built for it. Two things to weigh: at £23 for the long boxer they cost more than most, and they do not accept returns on underwear once it has been tried on, although Runderwear's 90 day chafe-free guarantee refunds you if a pair makes you chafe.
Boody Boyleg Briefs and Seamfree Undershort
Best for: a seamfree pair under fitted leggings, in UK 6 to 22
| Price | £13 for the Boyleg Briefs, or £18 for the 6 inch Seamfree Undershort (8 October 2026). UK delivery free over £45, otherwise £4.50. |
|---|---|
| What you get | Knitted as a tube, so no side seams, in 79% viscose from bamboo, 15% nylon and 6% elastane, XS to 4XL (UK 6 to 22). |
| Pros | Seamfree, a wide range of styles, and a 6 inch undershort that reaches where thighs touch. |
| Cons | Sizes stop at UK 22, and Boody does not take back opened underwear unless it is faulty, apart from a Comfort Guarantee on your first single pair. |
Boody is seamfree, so under very fitted leggings they show less. The range goes to 4XL (UK 22). Their boyleg is short, so it will not reach where thighs touch, but Boody also makes a 6 inch Seamfree Undershort, at £18, that does.
Step One Women's Body Shorts
Best for: a bamboo viscose short on a budget
| Price | £15 a pair, with 36 of its 40 colours at £9 in its sale (8 October 2026). Free UK delivery. |
|---|---|
| What you get | 95% bamboo viscose and 5% spandex, with Step One's Ultraglyde anti-chafe panels, XS to 4XL. |
| Pros | The cheapest bamboo viscose option here in its sale, and a 30 day guarantee on your first single pair. |
| Cons | No published leg length, its size guide stops at 2XL, and its refund policy says sale items cannot be refunded. |
Step One is the cheapest bamboo viscose option in its sale: £15 a pair, with 36 of its 40 colours at £9 when we checked on 8 October 2026, though its refund policy says sale items cannot be refunded. They do not publish an inseam for the women's Body Short, which matters if you are buying to stop thighs rubbing.
What goes wrong with normal underwear at the gym
It rides up. A brief with a high leg cut has almost nothing holding it in place once you start moving. Squats, lunges and anything on a mat make it worse.
Thighs rub. No coverage means skin on skin, and by the second half of a class that stings.
The waistband sits exactly where your leggings' waistband sits. Two elastics in the same place is a mark on your skin and a line under your clothes.
It stays damp. Cotton absorbs sweat and holds it. That is fine for a walk and unpleasant for an hour of cardio.
What to look for
A leg of 6 inches or more. This is the whole point. Most underwear marketed to women stops between 2 and 4 inches, which does not reach where thighs actually touch.
A wide, flat waistband. It should sit above or below your leggings' band, not on it.
Flat, bonded or seamfree edges. Overlocked seams sit proud and rub under a fitted legging.
A fabric that moves moisture rather than absorbing it. Bamboo viscose, modal and technical synthetics all do this. Cotton does not.
Check the returns policy. You cannot try underwear on, and some brands accept nothing once worn.
And a leg band that grips without digging, which is the thing most brands get wrong. Runderwear use silicone grippers, we use a wider band and a longer leg. Both approaches work.
Which fabric is best for gym underwear?
Technical synthetics dry fastest and are what you want for high-output running or anything where you will be soaked.
Bamboo viscose is buttery soft, breathable and moisture-wicking: it moves sweat away rather than holding it. Good for weights, classes, walking and moderate cardio. A cool wash and no fabric softener keep it that way.
Cotton absorbs and holds. Fine for a gentle session, poor for anything sweaty.
Merino is excellent and expensive.
Our take: for the gym, bamboo viscose is a strong choice: buttery soft, breathable and cool, and it moves sweat rather than sitting in it. For a long summer run, a technical synthetic dries faster, and our running comparison covers those.
Getting the length and size right
This is what decides whether long-leg underwear works for you when you are moving, and it is worth two minutes before you buy.
Start with the 6 inch. It sits mid-thigh, covers the top of the inner thigh where most rubbing starts, and comes in every colour and size, for classes, weights and walking as well as everyday wear. The 9 inch sits just above the knee, in black and pine green, if you already know you like a longer leg.
Today I've been on an 11 mile hike in the Peak District and I didn't have to fuss with them once. They never rolled up under my trousers and the waistband was unnoticeable.
P.O., UK, verified review
Size up if you are between two. These work through full contact with the skin. A tighter leg has to stretch further and grips less evenly, so sizing down makes bunching more likely rather than less.
Being a size 16-18, horse riding 5/6 days a week, walking more than 18,000 steps a day. Soft, super comfortable, stretchy, breathable and ZERO CHAFFING. Just ordered 5 more.
A.R., UK, verified review
Get both right and they stay where you put them. If the size is not right, we swap your whole first order free, as long as you try one pair and send the rest back unopened.
Under leggings
Fitted leggings are the hardest test for any underwear, so it is worth knowing what to expect.
A longer leg usually shows less than a brief, because the seam runs under the curve of the buttock rather than straight across it. Under very thin or very light leggings, though, any edge can show, whatever you are wearing.
If chafing or ride up is the problem you are solving, the longer leg of Flissie women's bamboo boxer shorts is the answer, and in a mid-weight legging it will not show. If a completely invisible line under very thin leggings matters most, a seamfree brief from Boody or a 360 degree seamless pair from Runderwear shows less.
What we make
We make Flissie women's bamboo boxer shorts: buttery soft bamboo viscose, with a 6 or 9 inch leg, UK 8 to 30, every size one price. Wide flat waistband, flat seams that do not dig or rub, no tag, dyed to OEKO-TEX Standard 100.
For the gym, start with the 6 inch, and size up if you are between two.
Great for exercise. Bought for marathon training and have been brilliant.
Emily, UK, verified review
The 60 Day Wear Test, free UK delivery, and a free size swap on your whole first order, as long as you try one pair and send the rest back unopened. See the range.
Not sure about the size?
Flissie women's bamboo boxer shorts run from S (UK 8 to 10) to 3XL (UK 28 to 30), all at the same price. If you are between sizes, size up, and if the size is wrong, we swap your whole first order free, as long as you try one pair and send the rest back unopened. Every order has free UK delivery and a 60 day guarantee: full refund, worn or not.
Gym underwear: your questions
What underwear should I wear to the gym?
Something with a leg long enough to stop thighs rubbing, a flat waistband that does not sit where your leggings' band sits, and a fabric that moves moisture rather than holding it. For most sessions that means a 6 to 9 inch boxer short or a technical brief.
What is the best gym underwear for women?
For classes, weights, walking and hot rooms, our pick is Flissie women's bamboo boxer shorts (we make them): buttery soft bamboo viscose with a 6 inch leg that stays put, in UK 8 to 30, with a 60 day guarantee, full refund, worn or not. For hard cardio and running, Runderwear's recycled polyamide dries fastest. For no visible line under very fitted leggings, a seamfree brief from Boody.
Should you wear underwear under gym leggings?
Most people do, and it is largely preference. Many leggings have a built-in gusset and are designed to be worn without. If you do wear something, a flat-seamed longer leg shows less than a brief and puts a layer between your thighs.
What underwear does not show under leggings?
Seamfree briefs and thongs show least. A flat-seamed boxer short usually shows less than a standard brief, because the seam sits under the curve rather than across it. Under very thin leggings, any edge can show.
Why does my underwear ride up at the gym?
Usually leg length or size. A short leg has more thigh to travel across, and underwear that is too small has to stretch further and grips less evenly. A longer leg and sizing up both help, which is why Flissie women's bamboo boxer shorts (we make them) have a 6 inch leg and a wide, flat waistband that stays put. Some brands use silicone grippers on the hem to do the same job.
Is bamboo underwear good for the gym?
Yes. Bamboo viscose is buttery soft, breathable and moisture-wicking, so it keeps you cool and moves sweat away rather than absorbing it, which is why customers wear Flissie women's bamboo boxer shorts (we make them) for classes, weights, hiking and walking. For high-output running in summer, a technical synthetic dries faster.
Does cotton underwear work for exercise?
Not well. Cotton absorbs sweat and holds it, so it stays damp. Fine for a gentle session, unpleasant for anything sustained.
What stops thigh chafing at the gym?
Coverage. A smooth layer between your thighs so they glide rather than catch, with a leg long enough to reach where they actually touch. Flissie women's bamboo boxer shorts (we make them) do this with a 6 inch leg in buttery soft bamboo viscose. We cover the mechanics on our anti-chafing shorts page.
How long should the leg be on gym underwear?
At least 6 inches, so it reaches where thighs touch; most underwear marketed to women stops between 2 and 4 inches. Flissie women's bamboo boxer shorts (we make them) come with a 6 inch leg that sits mid-thigh, in all 8 colours and every size from UK 8 to 30. The 9 inch sits just above the knee, in black and pine green, if you already know you prefer a longer leg.
How much does good gym underwear cost?
Between £9 and £23 a pair for the options here, checked on 8 October 2026: Step One's Body Shorts are £15, with most colours at £9 in its sale; Boody's Boyleg Briefs are £13 and its 6 inch undershort £18; and Runderwear's 8 inch long boxer is £23. Flissie women's bamboo boxer shorts (we make them) are £13.50 a pair, or £11.50 a pair in a 10 pack, with free UK delivery.
Is Runderwear worth it?
For running and hard cardio, yes: 360 degree seamless construction, silicone grippers on the leg hems and a recycled polyamide that dries faster than anything natural. It costs more than most, at £23 for the 8 inch long boxer, and outside its 90 day chafe-free guarantee it does not accept returns on underwear once tried on. For classes, weights and walking, Flissie women's bamboo boxer shorts (we make them) have a 6 inch leg and a 60 day guarantee with a full refund, worn or not.
Sources
Prices, fabrics and policies were checked on each brand's own UK website on 8 October 2026. Prices change often, so check before you buy. We have no commercial relationship with any of these brands.
- Runderwear: Women's Running Long Boxer Shorts
- Runderwear: Women's Running Briefs
- Runderwear: returns and chafe-free guarantee
- Boody UK: Boyleg Briefs, Seamfree Undershort 6 inch and Comfort Guarantee
- Step One UK: Women's Body Shorts and refund policy
The 60 Day Wear Test
Ready to train without the rub?
Try Flissie women's bamboo boxer shorts for 60 days. If they ride up, rub or roll, you get a full refund, worn or not.
Choose my pair£13.50 a pair, 6 for £75 or 10 for £115 (£11.50 a pair). Free UK delivery. Return postage is at your cost.
Written by Phillippa and Matthew, the founders of Flissie. We make the Flissie women's bamboo boxer shorts on this page.
Related reading
- Moisture wicking underwear: does it actually work?
- Best running underwear for women
- Chub rub: what causes it and how to stop it
- Anti-chafing shorts
- Best hiking underwear for women: what actually works on a long day
- Why does my underwear still show under my trousers?
- No VPL knickers: 7 options compared
