Before I openly declare my love for my On running leggings, let me say this: I made a pretty major mistake ahead of my first-ever half-marathon training block. I assumed that running trainers were the one investment I'd need to make — that my seasoned gym leggings and years-old sports bra would do.
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Eight weeks of chafing and regular breaks to pull up my leggings, and it dawned on me that, perhaps, I could have made my life easier — and possibly hit a few more PBs — had I invested in suitable activewear.
Hence why, ahead of embarking on my third training block, I've spent my fun runs testing a host of stretchy contenders to see which would be up to hundreds of miles of road-running. Enter: On's Studio Leggings.
| Sizes | XS — XXL. |
| Inseam | 26". |
| Material | 73% recycled polyamide, 27% elastane. |
| Care | Machine wash. |
Granted, the brand says the soft-touch, semi-sculpting leggings are best suited for low-impact activities — yoga, Pilates, low-impact training and the like. Yet I fall into the camp of (amateur) runners who don't like their bottom layers to be too compressive. Rather, these feel like a second skin; form-fitting without being overly compressive. Essentially, no movement is restricted.
For context, I'm a UK size 12 and fall just under 5'7", so I opted for a size medium — and to my surprise, these full-length leggings actually live up to their name, even ruching a little at the ankle. That's no bad thing, though; the extra material prevents them from escaping whatever running socks I tuck them into.
At the waist, I'd be lying if I said there wasn't some movement — but that's to be expected when you're attempting to keep a pace under 5:30 per km. Although for those debating between two sizes, go smaller.
My only constructive pointer? Can we have some more fun colour and pattern options, please? Saying that, classic black and navy work with my existing rotation of running jackets, while the Mineral (more seafoam green) is a universally flattering hue that shouldn't reveal your sweat marks — or, as I've rebranded them, signals of your hard work.
| Pros | Cons |
|---|---|
| Fit close to the body without limiting movement. | Size down one to prevent (minor) slippage. |
| Four-way stretch fabric is soft against the skin and smooth to the touch. | Neutral design options only. |
| The phone pocket on the right is handy for mid-run gels. | |
| High-waisted, plus the missing front seam prevents any unflattering caving. | |
| Crafted from 73% recycled materials. |
On running leggings: The Verdict
To summarise, here's the appeal of this pair of On running leggings. Want full-length lengths that don't slide, twist or split, even after 200 miles? But, being crafted from On's unique SenseTec fabric, they're also all-weather appropriate — the somewhat fleecy material keeps me cool in those early spring winds, but dries quickly post-workout when I head straight to brunch.
In terms of sizing, I'd say they're true — although to ensure they stay put, I'd consider sizing down one. I personally found, in the size below, the four-way stretch fabric still accommodated my curves, but required less manhandling mid-run.
And while I'm just a girl who loves a pastel or pink pair of running leggings, I can't complain that the classic hues of black and navy both fit easily into my existing rotation of activewear.
My other On essentials:
Because a runner's not going to get very far without a supportive pair of running shoes — and this vest is one I trust to hold my two water pouches, running gels and emergency supply of Percy Pigs.
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Why you can trust me:
A bit of context: I've been a wellness-focused commerce writer for almost three years — that's 12 months writing for Women's Health and Cosmopolitan, followed by 18 at Glamour. In that time, I've been tasked with reviewing everything from activewear (including yoga leggings and gym trainers) to dry robes, menstrual products such as period pants and the latest sexual wellness devices. That means I've tried thousands of products across hundreds of brands, and so am more clued up on the subject of wellness than your average online shopper.
As a result, my working week involves attending countless press events, interviewing activewear designers, women's health experts and sex therapists, plus keeping up to date on the latest wellness research.
In terms of my experience running, I'm a cliché. I used the first lockdown to complete Couch to 5K and ran my first half-marathon 12 months after that. To date, I've completed both the Manchester Half Marathon and the Royal Parks Half, and am set to take on the latter again this October. I run three to four times a week, and favour interval training over Fartlek, and a flat route over hills.
When reviewing running leggings, I aim to wear them for at least four runs of varying lengths before rating them against the following criteria:
| Design | Are they practical, fit for purpose and aesthetic? |
| Fit | Are they true to size? Are there options in terms of length, style and design? |
| Support | Do the running leggings offer some compression without limiting my movement? Does the waistband roll or slide down? |
| Price point | Would I be willing to spend that much on a pair of running leggings again? Are they good quality? Will they last, and do they wash well? |
| Delivery | How quickly did they arrive, and what were the associated costs? |
