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The Training Set

The Training Set

Regular price $66.00
Regular price $66.00 Sale price $117.00
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★★★★★ 4.7 / (146)

The Training Set

$117.00 $66.00
Size :
xs
Product fit
Small Perfect Loose
Low on stock. Get it while you can!
1
Free UK Delivery over £65
Free UK Returns & Exchange
3 payments of $22.00 with Klarna. Check purchase power.

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Why we made this +
Your workout drawer, sorted. Featuring three Workout Thongs and our Scuba Pouch, designed to keep your essentials in one place and move with you through every session. Crafted from moisture-wicking performance fabric with a stay-put fit and minimal VPL, it's built to keep up with every squat, sprint and stretch.
Details +

• Three Workout Thongs

• Scuba Pouch included

• Minimal VPL

• Moisture-wicking fabric

• Stay-put fit

• Four-way stretch

• Extra-long antimicrobial gusset

• Fast drying

• Made for movement

Fabric and care +

• 80% Recycled Nylon, 20% Elastane
• Extra-long gusset: 92% TENCEL™ Micromodal, 8% Elastane
• OEKO-TEX® certified (26.HCN.12854)

Made to perform, workout after workout.

• Cool wash, 40°C max
• Air-dry flat in a shaded area
• Do not iron or tumble dry

Shipping and returns +
  • UK: free over £65. Standard 2–3 working days, or Next Working Day if you order before 3pm.
  • International: Please check our FAQs
Sizing +

Not sure?

The Training Set : XS

unparalleled performance

Boost your confidence with underwear engineered to be worn under gym leggings 

Goodbye Distractions

Experience unparalleled performance with our premium workout underwear, meticulously engineered to stay in place and eliminate distractions. No more rolling or bunching.

Moisture-free

We chose a fast-drying recycled nylon to keep you sweat-free whilst you exercise. Why? Because regular cotton underwear retains moisture when you sweat leading to unwanted infections.

Designed to move

Featuring a 4-way stretch, The Workout Thong moves seamlessly with you, ensuring squat-proof confidence and ultra-comfortable wear both in the gym and every day.

frequently asked questions

Same thong shape, different fabric. The Everyday Thong uses ultra-soft modal designed for daily comfort under work clothes, jeans, and dresses. The Workout Thong uses a moisture-wicking, quick-dry performance fabric engineered to handle sweat and movement during exercise. If you’re heading to the gym, choose Workout. For everything else, choose Everyday.

Yes. The Workout Thong is designed to stay put during high-intensity movement — including squats, deadlifts, running, and HIIT. The flat leg elastics and secure waistband prevent bunching and riding up.

Absolutely. It works for everything from hot yoga to weight training. The moisture-wicking fabric handles sweat, and the flat seams prevent any chafing during floor work and stretching.

If visible panty lines under leggings bother you, or if you find briefs bunching during certain movements, the Workout Thong solves both problems.

Our core colour Black is always available and restocked regularly. Fashion colours and seasonal drops are limited edition — once they sell out, they won't be coming back. If you spot a colour you love, we'd recommend grabbing it before it's gone. Follow us on social or sign up to our mailing list to be the first to know when new color drops land.

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Customer reviews

4.7
★★★★★
146 reviews
5
4
3
2
1
Fit
SmallPerfectLoose
What customers say ✦ Auto-generated
Reviewers consistently praise The Training Set for its incredibly soft, buttery fabric and secure fit that stays perfectly in place without visible lines under leggings during intense workouts. Many also commend its flattering design, effective sweat-wicking properties, and overall comfort, making it an essential activewear staple from Underdays.
Avatar for Alexandra C
Alexandra C ✚ ✦ Verified
buyer
★ ★ ★ ★ ★

Great underwear, as expected

i wasn’t sure what to expect from these as compared to the everyday thong, but I loved the color way and wanted to try. They are comfortable, the fit is great, and the material is more of an athletic material. Would definitely buy again

♥ Would recommend
21 days ago
Fit
SmallPerfectLoose
Avatar for Angela G
Angela G ✚ ✦ Verified
buyer
★ ★ ★ ★ ★

Love them

Oh I absolutely love them. So comfortable and don't move around. They fit nice even for a larger lady

♥ Would recommend
last month
Fit
SmallPerfectLoose
Avatar for Hannah H
Hannah H ✚ ✦ Verified
buyer
★ ★ ★ ★ ★

Love them!

Super comfy! Great quality

Review for The Training Set - M
♥ Would recommend
3 months ago
Fit
SmallPerfectLoose
Avatar for Asweeni J
Asweeni J ✚ ✦ Verified
buyer
★ ★ ★ ★ ★

Very comfortable to wear!

Very comfortable to wear!

Review for The Training Set - L
♥ Would recommend
3 months ago
Fit
SmallPerfectLoose
Avatar for Samantha K
Samantha K ✚ ✦ Verified
buyer
★ ★ ★ ★ ★

Love these!

I absolutely love the workout thongs and this colour is especially lovely for under leggings which aren’t entirely squat proof. A joy to wear and honestly - I’m slowly swapping out my knicker drawer for more of these!

♥ Would recommend
4 months ago
Fit
SmallPerfectLoose

Reviews

4.7
★★★★★
146 reviews
5
4
3
2
1
Fit
Small Perfect Loose
What customers say Auto-generated
Reviewers consistently praise The Training Set for its incredibly soft, buttery fabric and secure fit that stays perfectly in place without visible lines under leggings during intense workouts. Many also commend its flattering design, effective sweat-wicking properties, and overall comfort, making it an essential activewear staple from Underdays.
Avatar for Alexandra C
Alexandra C ✦ ✦ Verified
buyer
★ ★ ★ ★ ★

Great underwear, as expected

i wasn’t sure what to expect from these as compared to the everyday thong, but I loved the color way and wanted to try. They are comfortable, the fit is great, and the material is more of an athletic material. Would definitely buy again

♥ Would recommend
21 days ago
Fit
SmallPerfectLoose
Avatar for Angela G
Angela G ✦ ✦ Verified
buyer
★ ★ ★ ★ ★

Love them

Oh I absolutely love them. So comfortable and don't move around. They fit nice even for a larger lady

♥ Would recommend
last month
Fit
SmallPerfectLoose
Avatar for Hannah S
Hannah S ✦ ✦ Verified
buyer
★ ★ ★ ★ ★

Love them!

Super comfy! Great quality

Review for The Training Set - M
♥ Would recommend
3 months ago
Fit
SmallPerfectLoose
Avatar for Asweeni J
Asweeni J ✦ ✦ Verified
buyer
★ ★ ★ ★ ★

Very comfortable to wear!

Very comfortable to wear!

Review for The Training Set - L
♥ Would recommend
3 months ago
Fit
SmallPerfectLoose
Avatar for Samantha K
Samantha K ✦ ✦ Verified
buyer
★ ★ ★ ★ ★

Love these!

I absolutely love the workout thongs and this colour is especially lovely for under leggings which aren’t entirely squat proof. A joy to wear and honestly - I’m slowly swapping out my knicker drawer for more of these!

♥ Would recommend
4 months ago
Fit
SmallPerfectLoose