Polyester wicks sweat and dries fast, polyamide (nylon) is soft, strong and abrasion-resistant, and elastane provides stretch and recovery, so performance kit blends them to combine sweat management, durability and freedom of movement. As of 2026, THETA uses each fibre where it does its best job, polyester for wicking tops, polyamide for soft tight outers, and elastane for stretch throughout.

• HYROX kit must wick sweat, survive sled and rack abrasion, and stretch through deep lunges, no single fibre does all three.
• THETA's Half Tight uses a polyamide/elastane outer with a polyester/elastane sweat-wicking liner.
• Blend ratios such as 89% polyester/11% elastane tune the balance of wicking, durability and stretch.

What does polyester do best?

Think of polyester as the workhorse of sweat management. It's hydrophobic, so instead of drinking water into the fibre it pushes sweat to the surface to evaporate, keeping kit light and quick-drying, which is exactly what a 60 to 120 minute HYROX asks for. It's durable too, holding its colour and shape through the frequent washing that hybrid training demands, and it can be engineered ultra-light. That's why THETA uses modified polyester with excess weight removed and woven-in breathable holes in its tops, and polyester-elastane blends in shorts. When the core job is keeping you dry and light, nothing common does it better.

What does polyamide (nylon) do best?

Polyamide, which you probably know as nylon, is the fibre you reach for when softness, strength and abrasion resistance matter. It feels smooth against the skin and shrugs off repeated stress, so it's ideal for the outer of a garment that takes contact and has to feel good over long wear. THETA uses an ultra-soft polyamide/elastane outer on the Half Tight and pairs that comfort and toughness with a separate wicking liner. The one catch, and it's a small one, is that nylon holds a touch more moisture than polyester, which is why it lives where softness and durability count more than the fastest drying.

What does elastane do best?

Elastane, sometimes sold under trade names, is simply the stretch fibre. Even a small percentage blended into a fabric gives it the ability to extend and recover, and that's what makes 4-way stretch possible in the first place. It does almost nothing for sweat management or abrasion resistance, so you'll never find it used alone, it's always riding along with polyester or polyamide. In HYROX kit, elastane is what lets shorts drop through a deep sandbag lunge and a low sled drive and then snap straight back, and what gives a fitted top freedom across the shoulders without gripping.

Why blend them rather than pick one?

Because each fibre quietly covers a weakness in the others:

1. Polyester wicks and dries but is not the softest, so nylon can add comfort where it touches the skin.
2. Polyamide is soft and tough but dries slower, so a polyester liner handles the sweat.
3. Elastane adds the stretch neither polyester nor nylon has much of on their own.
4. Blend ratios tune the balance, more elastane for stretch, more polyester for drying.
5. The Half Tight shows the logic: soft nylon outer, wicking polyester liner, elastane in both for stretch.

"There is no magic single fibre. The skill is putting each one where it works, wicking against the skin, softness and strength on the outside, stretch throughout," says the THETA coaching team.

How should this guide your choice?

So read the fabric content and match it to the job, it really is that simple. For a race or training top where staying light and dry is everything, you want polyester or polyester-elastane. For a tight or soft short where comfort and abrasion resistance matter, a polyamide-elastane outer with a wicking liner is the sweet spot. And for anything with deep range under load, just make sure elastane is in the blend for that 4-way stretch. Helpfully, THETA labels its blends, such as 89% polyester/11% elastane, so there's no guessing what balance you're getting.

Common questions

What is the difference between polyester and polyamide?

Polyester wicks sweat and dries faster and lighter, while polyamide, or nylon, is softer, stronger and more abrasion-resistant but holds slightly more water. Kit often uses polyester for wicking layers and polyamide for soft, tough outers.

Is polyamide the same as nylon?

Yes. Polyamide is the technical name for the fibre family commonly called nylon. THETA uses a polyamide, or nylon, outer on the Half Tight for its softness and durability.

What does elastane actually do?

Elastane provides stretch and recovery, letting fabric extend and snap back. It is always blended in small amounts with polyester or polyamide because it does not wick or resist abrasion on its own.

Why do tights have two different fabrics?

The Half Tight uses a soft, durable polyamide-elastane outer and a separate polyester-elastane wicking liner, so the outside feels good and lasts while the inside manages sweat against the skin.

Does a higher elastane percentage mean better kit?

Not automatically. More elastane means more stretch, but you still need enough polyester or nylon for wicking and durability. The right ratio depends on the garment's job, which is why blends are tuned.

Which fabric is best for a HYROX top?

A polyester or polyester-elastane top, because polyester wicks and dries fast to stay light, and the elastane adds freedom of movement. This is why THETA's tops are built on modified polyester.

Sources

• HYROX official race format (hyrox.com)
• THETA coaching and product testing data, 2024–2026
• Established textile science (fibre properties of polyester, polyamide and elastane)

Want kit that puts each fibre where it belongs? THETA blends polyester, polyamide and elastane by job across its range. Explore the THETA performance kit.