Fit
The Gymshark Flex fits differently than most leggings — intentionally so. Strategic seam placement along the thighs and glutes creates a subtle sculpting effect that’s visible from the first wear. The paneling isn’t just aesthetic; it’s engineered to contour the body and create the appearance of a lifted, rounder silhouette. For gym wear, this is a meaningful design choice.
The high-rise waistband sits comfortably above the hip and covers the midsection cleanly. The fabric has genuine compression — not extreme, but enough to feel held-in during a workout rather than just draped. This is not a zero-compression fabric like Nulu. The Flex is designed to shape and support.
Where the fit can fall short: some reviewers with a shorter torso or more rounded stomach report the waistband folding over during squats or lunges. This isn’t universal — it’s body-type dependent — but it’s worth knowing before you buy. If you’ve had folding issues with other high-rise leggings, this one may exhibit the same behavior.
Sizing runs true for most people, but colorways can vary slightly in cut. If you’re buying a new color, check the specific product reviews.
Fabric & Feel
The Flex fabric is a 79/21 polyester-elastane blend — smooth, firm, and performance-oriented. It doesn’t have the buttery softness of Nulu or Butterluxe. That’s by design. The Flex is a gym legging, and the fabric reflects that: it’s built for movement, sweat, and durability rather than skin-like comfort.
Moisture-wicking is excellent. The fabric pulls sweat away from the skin quickly and dries fast enough that you won’t feel damp mid-workout. For HIIT, weight training, cycling, and similar activities, this fabric performs reliably where softer fabrics fail.
Squat-proof performance is a genuine selling point. The Flex is opaque at every angle, even in lighter colors, and the fabric doesn’t shift or ride up during deep squats. This is the test that eliminates many competitors, and the Flex passes it cleanly.
Durability
Gymshark’s construction is noticeably solid. Seams are reinforced at stress points, stitching doesn’t unravel at the waist or ankle, and the fabric maintains its shape and opacity through months of washing. Pilling is minimal compared to softer fabrics — the polyester-heavy blend is more resistant by nature.
Owners frequently report these leggings looking near-new after a year of regular gym use. The fabric doesn’t thin, the seams don’t fray, and the waistband doesn’t lose its elasticity. For a $55 legging that you’ll wear three or four times a week, that durability calculus is favorable.
Standard care applies: cold wash, no fabric softener, air dry when possible. Machine drying accelerates waistband degradation over time.
Value
At $55, the Gymshark Flex sits in the mid-market. It’s more than budget options but significantly less than Lululemon’s performance line. For gym use specifically, the price-to-performance ratio is strong. You’re getting sculpting seams, squat-proof construction, and durable fabric that holds up through heavy use — all features that cheaper options fail to deliver consistently.
The value comparison shifts if you’re looking for a multipurpose legging. For yoga, lounging, or walking, the Flex is overbuilt — you’d be paying for gym features you don’t need. For those use cases, the CRZ YOGA Butterluxe or Lululemon Align would serve better at the same or lower price.
For the gym, though, the Flex is hard to beat in its price range.
Who It’s For
The Gymshark Flex is for regular gym-goers who want a legging that does its job without complaints. If your workout involves squats, lunges, or any movement that puts sheer leggings to the test, this is a reliable answer. It’s also a good choice for people who want a sculpting silhouette during workouts — the seam placement does real work on that front.
If your primary use case is yoga, pilates, or lounging, look at the Lululemon Align or CRZ YOGA Butterluxe instead. The Flex earns its reputation in the gym; it’s not the most comfortable option outside of one.
