HIIT (high-intensity interval training) is the most demanding test for activewear. You need fabric that wicks sweat, waistbands that don't move during box jumps, sports bras that hold during jumping jacks, and nothing that restricts a full squat or lateral lunge.
Here's a practical guide based on what the community actually wears.
Leggings: what HIIT demands
Stay-put waistband: Any legging with a soft, narrow, or stretchy waistband will roll down during floor work. Look for a wide structured waistband with at least 7–8cm of height.
Opaque under all conditions: Test your leggings with a phone torch to the back before doing HIIT in them. If you can see through, you'll see through in a forward bend.
Squat depth: The legging needs to follow your hip crease without restriction in a full squat. Woven or structured fabrics (some Nike, Gymshark Adapt) can restrict range of motion at depth.
Sweat handling: You will sweat. A lot. Fabrics that go see-through when wet (thin Nylon/Lycra blends) are not HIIT fabrics.
Best HIIT leggings by community vote:
- Nike Go Leggings (Dri-FIT ADV) — stiff enough to stay up, compressive enough to support
- Gymshark Training Leggings — more woven than seamless, holds its shape under load
- Sweaty Betty Power Leggings — go-to for women who want compression without restriction
- Lululemon Fast and Free — lighter compression, excellent range of motion
Sports bras: the HIIT test
You need encapsulation or combination support for anything above a B cup. Jumping, burpees, and tuck jumps create more vertical movement than running — which means a bra that works for 5k may not hold up in a 20-minute HIIT class.
Adjustable straps matter. During a HIIT class you may need to tighten after warming up.
Best options:
- Gymshark Flex Sports Bra (A–C cup, medium-high impact)
- Sweaty Betty Stamina (B–D cup, high impact)
- Shock Absorber Ultimate (D–G cup, high impact)
Shorts vs leggings for HIIT
Shorts are better for hot HIIT classes because less fabric = less overheating. The trade-off is modesty in floor work — if you're doing box jumps, sprawls, and burpees, make sure shorts are long enough to cover fully in all positions.
Bike shorts (mid-thigh length) are the best compromise — coverage in floor work, cooler than full leggings.
What not to wear
- Cotton: Absorbs sweat and stays wet. Gets heavy. Chafes.
- Loose shorts without compression lining: Will move everywhere during dynamic work
- Thin seamless fabrics (Gymshark Vital in lighter colours): Show sweat and can go transparent
Keep it simple. Dark colours, structured waistband, opaque fabric, good bra. Test at home before class.