To find your size in women's performance kit, start from your usual women's size, then use the fitted-chest, relaxed-stomach principle and the product page fit notes to confirm the exact fit rather than defaulting up or down. THETA cuts precisely per size, so the right choice sits close through the chest and shoulders with room to brace at the stomach.
- THETA's tech tops are precision-cut per size and built to a fitted-chest, relaxed-stomach standard.
- The women's range is engineered by THETA's female athletes for freedom of movement with controlled structure, as of 2026.
- A HYROX race is worn through 8km of running and 8 stations, so fit under movement matters more than fit standing still.
Where should you start with sizing?
Start from your usual women's size. Do not borrow a men's equivalent, and do not guess. THETA's women's kit is cut for a women's frame and precision-cut per size, so your true size is the right first reference. From there the product page fit notes tell you whether a specific piece runs closer or roomier, which matters because a race singlet and a training tee do different jobs. Sizing is a starting point plus a check. It is not a guess.
What does "fitted chest, relaxed stomach" mean for choosing a size?
Most people size up for comfort. It is the wrong instinct here. THETA cuts tops to sit close through the chest and shoulders while leaving room at the stomach, so the right size feels snug up top and easy through the middle. Loose across the chest and shoulders means the top is too big, and it will flap on the run and ride up overhead. Restriction at the ribs or the brace at the stomach means it is too small. Read both cues together, and if a size fits the chest but pulls at the stomach, let the fit notes guide you rather than simply sizing up.
How should shorts and waistbands fit?
Shorts should sit secure at the waist without digging. The body should be squat-proof and stay opaque at depth. THETA's Women's Gym Shorts use a 3-tier waistband that stays anchored under load, so the right size holds without over-tightening. Test it. Squat and lunge deep: the fabric should stretch freely and recover to shape, and the waistband should stay put. If you have to cinch it hard to stop it sliding, size down. If it digs at the waist, size up, and check the fit notes for the specific short.
| Sign | Meaning | Action |
|---|---|---|
| Loose across chest and shoulders | Top too big | Size down or check fit notes |
| Restricts brace at stomach | Top too small | Size up |
| Waistband digs | Short too small | Size up |
| Waistband slides at true tension | Short too big | Size down |
How do you confirm the size is right?
- Start from your usual women's size and read the product page fit notes for that piece.
- Check the top is fitted across the chest and shoulders with room at the stomach.
- Raise your arms overhead and confirm the hem stays near the waist.
- Squat and lunge deep to confirm the shorts stretch, recover and stay opaque.
- Test the kit soaked in a full session, since sweat changes how fit and coverage behave.
"The most common sizing mistake is defaulting up for comfort. Our tops are cut fitted at the chest and relaxed at the stomach on purpose, so your true size usually is the comfortable one. Trust the fit notes and test it moving," says the THETA coaching team.
Why does testing under movement matter?
Kit that fits standing still can still fail once you move. Running, reaching and lunging reveal the ride-up, sliding and gapping a mirror hides. A race top is worn through 8km and 8 stations, so the real test is whether it stays anchored overhead and covered at depth, not how it looks standing there. That is why you rehearse your size in a full soaked session. If it stays put and comfortable through the movements that matter, the size is right. If not, the fit notes guide the adjustment.
Common questions
How do I find my size in women's performance kit?
Start from your usual women's size, then confirm with the fitted-chest, relaxed-stomach cue and the product page fit notes. THETA cuts precisely per size, so your true size is usually correct rather than sizing up for comfort.
Should I size up in performance tops?
Usually not, because sizing up adds loose fabric that flaps on the run and rides up overhead. THETA's relaxed-stomach cut already provides bracing room, so stick to your true size unless the fit notes say otherwise.
How should a women's performance top fit?
It should sit fitted across the chest and shoulders with room at the stomach, staying anchored when you reach overhead. Loose across the chest means too big; restriction at the stomach means too small.
How do I know if shorts are the right size?
The waistband should stay secure without digging, and the squat-proof body should stretch, recover and stay opaque at depth. If you must over-tighten to stop sliding, size down; if the waist digs, size up.
Do THETA's women's pieces run true to size?
They are precision-cut per size to a fitted-chest, relaxed-stomach standard, so starting from your true size is the right reference. Check each product page's fit notes, since a race singlet and a training tee can fit differently.
Why should I test kit soaked before deciding on size?
Sweat changes how fit and coverage behave, so a full soaked session reveals ride-up, sliding or gapping you would not see standing still. If the kit stays anchored and covered through movement when wet, the size is right.
Sources
- THETA product development notes and female-athlete testing, 2024–2026
- HYROX race format and station demands (hyrox.com)
- Established principles of technical-garment fit and sizing
Get the size right the first time. Check the per-size fit notes across the THETA performance kit on each product page before you buy.