Size THETA kit to your chest, not your stomach. The range uses a fitted-chest, relaxed-stomach cut, so tops are trim across the shoulders and chest and ease slightly through the midsection. Pick the size that fits your chest cleanly and you get the intended athletic silhouette without the fabric pulling at the stomach. When you are between sizes, chest measurement decides it.
- THETA's tops use a fitted-chest, relaxed-stomach cut across the Tech, Core and Race lines as of 2026.
- The fit is designed for full overhead range on wall balls and SkiErg without riding up.
- The Tech T-Shirt Race Team v2 is precision cut per size, so following the fit notes matters more than guessing.
What does fitted chest, relaxed stomach actually mean?
The top is cut close through the shoulders and chest, then given a little more room through the stomach. That gives an athletic shape without clinging at the waist. Most athletes carry a touch more there, or bloat during a long, heavy session. The cut avoids two problems at once: a boxy fit up top and an unflattering pull across the midsection.
The payoff is comfort under load. A chest-fitted top stays put during overhead work on the wall balls and SkiErg. The relaxed stomach means the fabric does not dig in when you fold into a deep lunge or breathe hard between stations. This is a fit built for movement, not for standing still in a mirror.
How should you measure for the right size?
Measure your chest at its widest point. Keep the tape level and under the arms, then check that number against the size guide on the product page. The chest anchors the fit, so it drives the choice. Your usual t-shirt size is a starting point and nothing more. The size guide is more reliable than assuming your habitual size carries across.
For shorts, focus on your waist measurement. The range uses a premium elasticated waistband and 4-way stretch, so there is some give, but you still want the stated waist range to match. The Tech Short v2 has a racing-specific fit. Do not oversize chasing a looseness that would undermine the intended cut.
What if you are between sizes?
Size to the chest. Going up to loosen the stomach leaves the shoulders and chest too baggy, which defeats the athletic fit and lets the top shift during overhead movements. Going down for a tighter look risks restriction across the chest and riding up. The stomach is already handled by the cut, so the chest is the only measurement that should decide it.
| Situation | What to do | Why |
|---|---|---|
| Between sizes on tops | Size to your chest | Chest is the anchor of the cut |
| Want a looser stomach | Stay true, don't oversize | The cut already relaxes the stomach |
| Prefer a trim race feel | True to chest, not smaller | Too small rides up overhead |
| Shorts | Match stated waist range | Elasticated waistband + 4-way stretch |
"The mistake we see is people sizing up to hide the stomach, then wondering why the top looks baggy and shifts on the wall balls. The cut already relaxes the stomach for you. Size to your chest and let the fabric do its job," says the THETA coaching team.
Why is this cut built for HYROX?
HYROX asks for full overhead extension on the wall balls and SkiErg, deep lunges under a sandbag, and hard breathing across 8 kilometres of running. A chest-anchored fit keeps the top secure through overhead reps so it does not ride up. The relaxed stomach leaves room to fold, breathe and bloat over a 60 to 90 minute effort. The 4-way stretch in the shorts supports the same range of movement.
Use this process to get your size right first time.
- Measure your chest at its widest point with a level tape.
- Compare it to the size guide on the specific product page.
- If between sizes, choose based on the chest measurement.
- For shorts, match your waist to the stated range.
- Test overhead reps and lunges to confirm nothing rides up or restricts.
Common questions
How does THETA kit fit?
THETA tops use a fitted-chest, relaxed-stomach cut, meaning they are trim across the shoulders and chest and slightly roomier through the stomach. This gives an athletic shape that stays in place during overhead work while allowing room to breathe and lunge. Size to your chest for the intended fit.
Should I size up or down in THETA tops?
Size true to your chest measurement rather than up or down. Sizing up to loosen the stomach leaves the chest and shoulders baggy, while sizing down risks restriction and riding up during overhead movements. The cut already relaxes the stomach, so your chest size is the right call.
How do I measure my chest for the right size?
Measure around the widest part of your chest with a tape kept level and under the arms, then compare that number to the product page size guide. The chest is the anchor of THETA's fit, so this measurement should drive your choice. Do not simply assume your usual t-shirt size transfers.
Does the relaxed stomach mean the top is loose?
No, it is not a loose top overall. It is fitted through the chest and shoulders with only a slight easing through the stomach, so the fabric does not cling or dig in at the waist during a hard session. The overall silhouette stays athletic rather than baggy.
How should THETA shorts fit?
Shorts use a racing-specific fit with a premium elasticated waistband and 4-way stretch, so match your waist to the stated size range rather than oversizing for looseness. The fit is designed to move through lunges and squats without riding up. Sizing up too far undermines the intended cut.
Is the Tech T-Shirt v2 cut the same as v1?
Both use the fitted-chest, relaxed-stomach cut, so the silhouette is consistent, but the v2 is precision cut per size for a more refined fit. Sizing generally carries across between the two. Check the fit notes on the product page to confirm.
Sources
- THETA product construction notes: fitted-chest, relaxed-stomach cut, precision-cut sizing, waistband and stretch
- THETA testing provenance: Elite 15, athlete-led design loop, 2 race seasons of fit testing
- HYROX official race format (overhead wall balls, SkiErg, lunges) informing the fit design (hyrox.com)
Getting the fit right the first time. Size THETA kit to your chest and let the relaxed-stomach cut do the rest, then move freely through every station. Shop THETA performance kit.