Brooks Adrenaline GTS 21 Review

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For 2 years straight, the Brooks Adrenaline GTS 21 has been flying off the shelves. Alongside the Ghost, it’s one of Brooks’ best-selling shoes – and for good reason.

Having been in the shoe game for over two decades, Brooks is amongst both the oldest and most successful running shoe companies globally. Their specialty is producing durable, everyday trainers with their innovative technology and specialized cushioning.

This model is one of Brooks’ medium cushion, stability shoes. While not made for speedy sprints, the stability and responsivity mean the Adrenaline 21 is built to withstand countless miles, including your everyday runs and training for marathons.

Even better, this model is covered by Brooks’ RunHappy Promise, meaning you can try them out for 90 days before you decide whether they’re right for you – a testament Brooks’ confidence in their designs!

Pros Cons
Secure, flexible fit Not made for speed runs
Good arch support (Guiderails) Breathability could be improved
Stability Toe box could be wider
Super Durable   
Brooks adrenaline gts 21

Brooks Adrenaline GTS 21: Features and First Impressions

The Outsole

Brooks are known for being super durable, and on unboxing the Adrenaline GTS 21, I was already sure that this model would be no exception.

You’ll immediately notice that there is a pretty thick covering of rubber on the outsole to defend against wear and tear. The outsole also features ‘omega flex grooves’, strategically located to improve flexibility and grip.

This is designed to protect the softer midsole foam but does also contribute to the shoe being slightly heavy at 292 g / 10.3 oz – although still lighter than the previous GTS 20.

Brooks adrenaline gts 21 review

The Upper

When it comes to the upper, the Adrenaline 21 is pretty similar to the previous model, the Adrenaline GTS 20.

This consists of a double-layered, engineered mesh – a little more structured than other shoe brands, and designed to allow the upper to keep its form and hug the foot more securely.

The laces are slightly elasticated and the tongue is gusseted – both features are designed to keep the fit secure while increasing breathability and flexibility in the upper.


With a stack height of 30mm, the Adrenaline 21 is considered a maximal running shoe. Like previous models, it uses Brooks’ popular DNA Loft cushioning – a firmer foam than other brands made of EVA foam, rubber, and air.

The drop of this shoe is 12mm, being 1mm less than the previous GTS 20, but still much higher than the running shoe average drop of 8-10mm.

Brooks adrenaline gts 21 review

Unlike previous models, however, the cushioning in this shoe has been extended from the heel up to the forefoot and a centimeter or two out from the lateral edge of the insole.


What makes the Adrenaline 21 a strong stability shoe is Brooks’ unique Guide Rails Support System.

Believing that the ‘correct’ way to run is simply your natural way, Brooks developed their Guiderail technology to support those with a tendency to overpronation and heel strikers, hoping to keep them safe from injury whilst allowing them to keep running in their own way.

The technology consists of two ‘guide rails’ – one on the inside of the foot and one on the outside, both towards the heel.

The former acts to stabilize the foot from the heel bone, preventing the arch from collapsing too far inwards. The latter reduces outwards rotation of the heel which causes the knee to twist. Thus they work together to keep the body moving along its natural line.

Illustration of a cross section of a Brooks shoe with GuideRails technology demonstrating placement of foam on each side of the heel.

Colours and Width Options

The Brooks Adrenaline GTS 21 also comes in an exceptionally broad variety of colors and shapes, with 9 colors and four width options (Narrow, Normal, Wide, and X-Wide) to choose from.

Brooks Adrenaline GTS 21: The Road Test

The first time I tried on the Adrenaline 21, two things stood out to me: the snug fit and the firm underfoot.

Brooks adrenaline gts 21 review

The Fit

We’ll start with the first standout: the snug fit.

The shoe hugged my foot nicely, with a super cozy upper, moderate but noticeable arch support, and a really comfortable padded heel counter with no slip issues.

The fit on the bridge of my foot felt a little too snug at first, but once I started moving, I was pleasantly surprised at how the gusseted tongue and laces flexed as my foot did, allowing for a nice smooth transition by preventing any restriction, rubbing or tightness.

Saying this, however, there was a little tightness on my lateral side towards the toe box, and on my first few runs, I did come away with some small chilblains on my outer toes.

I’m putting this down to a few things. The first is simply breaking in, with Brooks being known to take a little longer to mold than other shoes.

The second explanation is breathability.

Brooks adrenaline gts 21 review

Developing chilblains normally happens when cool skin is exposed to heat quickly, and I think what was happening in my first few runs was that the heat from my feet was getting trapped in the shoe due to slightly limited breathability.

A final explanation that has been noted by a few other reviews is that the toebox of this model could be a little wider. Our feet swell when we run, and while the toebox felt fine at first when I started running my toes began to feel a little bunched and restricted.

However similar to the other issues that I experienced with this shoe, the breathability issue seemed to disappear as I wore the shoe in. The toe box also feels more comfortable now after a few miles, although I’d still prefer a bit more room for my toes to splay.

The Landing

The second standout was down to Brooks’ DNA Loft foam, which creates a much firmer landing than ‘marshmallow softness’ running shoes such as the Hoka Clifton 8.

Saying this, it still felt pretty soft, nicely responsive, and only got better the more miles I ran. The firmness was definitely noticeable at first, but after a few runs, I found that the foam broke in nicely, becoming more supple.

Brooks adrenaline gts 21 review

This break-in is actually part of Brooks’ smart design. Over time, the midsole is designed to soften in the places of greater repeated impact – i.e. the places where you need it most.

As I ran more, I started to appreciate the extended and added DNA cushioning more and more. The higher stack height that this has created compared to the GTS 20 or 21 has done wonders for the landing and transition of this newer model.

The landing surface area has become slightly larger as a result of the extended cushioning, managing to improve the stability and shock absorption of the shoe, without making the landing overly plush.

The transition of the shoe also feels smoother than the previous Adrenaline GTS 19 and 20 models that I’ve tried, partly thanks to the added cushioning.

A lot of people have complained about the drop of this shoe being a little too high at 12mm.

I must say this isn’t something I really found any issue with unless I was going down a slope, where it became a little more noticeable and definitely led to me holding back the pace slightly (which isn’t necessarily a bad thing when running downhill!).

Brooks adrenaline gts 21 review

The Stability Support

Being in northeastern Spain where we’re blessed with lots of different terrains, I was lucky to be able to test these bad boys out on various surfaces – from urban areas, sand, track, grassland, rocky mountain runs, and softer forest trails.

For a road running shoe, I was pretty impressed with how the Adrenaline GTS 21 performed in all these environments, proving to be much more versatile than I was expecting.

It was actually running on these uneven surfaces that I could really appreciate the GuideRails Technology. I’m a mild overpronator, and running on unpredictable surfaces often seems to make this worse, but my foot felt really stable and supported throughout.

Brooks adrenaline gts 21 review

What is great about the GuideRails technology is that it’s pretty subtle and only kicks in when and to the degree that I needed it, meaning the shoe is also suitable for those with more neutral pronation.

The grip was definitely better on loose surfaces than it was on wet surfaces, but was pretty good on both.

While the landing and stability of the shoes were ace, it wasn’t the easiest model to pick up pace in – which is to be expected as this is designed as a daily trainer, not a speed shoe.

Brooks adrenaline gTS 21 review: The Takeaways

We’re coming to the end of our Brooks Adrenaline GTS 21 review – so, what are the key takeaways, and who should/shouldn’t buy them?

Overall, the Brooks Adrenaline GTS 21 is perfect for those looking for a versatile daily running shoe. Flexible, snug, stable, and durable, it performs superbly for your easy miles, long distances, and fares well on various terrains.

Brooks adrenaline gts 21 review

As mentioned, this is a daily trainer slightly on the heavier side, which isn’t built to encourage you to move at a high pace. So if you’re looking for shoes best for speed runs, this probably isn’t the one for you.

Related Article: Saucony Endorphin Speed 2 Review

Likewise, if you’re impatient with your shoes and want shoes ready to go right away, Brooks Adrenaline might not be the right choice. For me, this is the biggest criticism of the GTS 21 – the long break-in time.

Most of the immediate issues such as slightly rigid landing, limited breathability, and tightness in the forefoot began to disappear after 20 miles or so as I wore in the shoes and only got better from there. But for some runners, this is simply too long a wait to keep faith.

However this is partly down to the resistant and durable materials that Brooks uses – so if you’re not in a rush, I guess a little break-in time is a fair trade-off for a great quality pair of trainers that will last you countless miles.

My recommendation would be to try this model for 90 days under their RunHappy Promisewhat have you got to lose?

Brooks adrenaline gts 21 review

Not Sure If the Brooks Adrenaline GTS 21 is right for you? Try the Saucony Endorphin Shift 2!

Another great high-mileage trainer, read our review of this star shoe linked below:

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Tish is a plant-based yogi and running enthusiast based in Brighton, UK. Having reaped the physical, spiritual, and mental health benefits of long-distance running, she's passionate about spreading the wonders of the sport to others. Having completed half marathons and marathons, she's now stepping it up a notch (or two!) and currently training for her first 100km!

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