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Hylo Athletics Impact Review
By Bach Pham and Matthew Klein

There is increasing talk about sustainability in the footwear world. As the realization has come regarding the excessive waste that occurs with the production and disposal of shoes, particularly running shoes. A few companies have debuted bio-based shoes, but most did not completely push into the performance realm. Hylo Athletics came onto the scene in 2022 with a fully green, bio-based shoe that was a learning experience. It was a firm, thin-soled shoe that served as a proof of concept for the company. The Hylo Impact is a completely different, serious performance running shoe. Featuring a large amount of nitrogen-infused sugarcane-based midsole with a competitive daily training weight and a comfortable fit, the Hylo Impact certainly lives up to its name.

Hylo Athletics Impact
Price: $165 at Running Warehouse
Weight: 9.8 oz, 280 g (men's size 9/women's size 10.5)
Stack Height: 39 mm / 31 mm
Drop: 8 mm
Shoe Purpose: Bio-Based Daily Trainer

Pros: Extremely well cushioned, stylish look, comfortable upper
Cons: Not super stable, small challenge with lace security


The Hylo Impact is a radical departure from their previous models for the brand. The Hylo Impact features a soft, neutral riding shoe with bio-based materials throughout. Sustainability very much remains at the forefront of the Impact. Their midsole, called Hyperbolt, is a high stacked, bio-based (spoonful of sugar) EVA that is nitrogen infused. There is also a 60% natural rubber outsole with a unique design and Rilsan knitted upper made from castor beans. The elements come together nicely in a very modern package that actually makes the sustainability story feel somewhat second fiddle.

: Puma Velocity Nitro 3, Saucony Ride 17
PAST MODEL: This is a new model

(To learn how a shoe should fit, check out our full podcast on fit by Matt Klein.)

Matt: The Hylo Impact fits me true to size in my normal men's US size 10. The upper is fairly comfortable, albeit slightly thick. The fit is normal throughout the length of the shoe and a little wider in the heel. The forefoot fits normally with a slightly tapered forefoot which makes it feel a tiny bit snug. This is offset by the flexible mesh upper and light toe guard which has no bothered me at all. The midfoot features a mild to moderately thin tongue that is gusseted and secure. The thicker laces do slide slightly but the midfoot is overall quite secure when they are tightened down. The heel fits slightly wide with a flexible heel counter and moderate heel collar cushioning. Despite the slightly wider fit, I have not experienced any heel slippage while wearing socks. The inner liner up the upper is extremely comfortable while sockless, however this causes a bit of heel slippage for me. Once I lace locked the shoe, this was fine. So with or without socks this upper does well but a few adjustments are needed for security without them. 

Typical Size: Men's US Size 10
Shoes that have fit Matt well: Saucony Guide 17, ASICS Kayano 30, Hoka Gaviota 5, Saucony Endorphin Elite, Nike Ultrafly
Shoes that have fit snug: Hoka Arahi 7, Saucony Kinvara 14
Shoes that have fit large: Salomon S/Lab Phantasm 2, Altra Timp 5

Bach: The Hylo Impact's upper is a very comfortable, standard foot size fitting shoe. The shoe worked for my regular men's size 9.5. The shoe's length is just very slightly short and snug at the big toe. The volume is just average. I had a little bit of room to wiggle, and the upper is fairly soft and malleable. As I got more miles in the shoe I didn't have any issues, but thin socks are definitely advised. I wouldn't necessarily size up unless you are between sizes as the heel is a bit looser. The midfoot is comfortable, leaning just a touch snug going into the forefoot.

I found the lockdown with a traditional lacing to work well for me. I didn't have slippage, but there was a faint feeling of not having the most full lockdown possible. This is due to the roomier heel to midfoot. I found the upper to be okay on breathability and the upper in general to be really cozy on foot. It's a soft material all-around. The insole is removeable here and the rearfoot has a flexible heel.

Typical Size: Men's US Size 10
Shoes that have fit Bach well: Nike Pegasus 40, Saucony Guide 17, Mizuno Wave Inspire 19, Saucony Endorphin Speed 3, Nike Structure 25
Shoes that have fit snug: Hoka Arahi 7, Asics Kayano 30, Puma Electrify Nitro, Brooks Hyperion, Hoka Clifton 9 GTX

Shoes that have fit large: Hoka Gaviota 5, Reebok Floatride Energy X

Doctors of Running Checklist

Is This a Good Shoe for Walking: Yes
Is This a Good Shoe for Standing: Yes
Is the Forefoot Flexible: Mildly
How Flexible is the Shoe: Not flexible but not stiff
Is This a Good Heel Bevel: Decent bevel but significant posterior flare
Recommended for Haglunds: Somewhat
Recommended for Sockless: Yes, but additional lacing security required
Durability Expectation: Above Average


Matt: The Hylo Impact is a maximal performance daily training shoe with a large amount of bouncy cushioning underfoot. The nitrogen-infused sugarcane midsole is highly cushioned and soft, reminiscent of FuelCell foam. It is a bit more soft than it is responsive, but can actually handle some pace changes. The weight feels lighter than the 9.8 oz (men's size 9) but the Hylo Impact does feel more on the training side of the spectrum. There is an 8mm drop listed with a tall 39mm / 31mm stack height. The heel drop feels higher than listed, mostly due to the large posterior flare which causes a slightly early initial contact. The heel does have a rocker geometry, although the large chunk of posteriorly flared midsole does make heel contacts a little clunky. This breaks in as the midsole is soft enough that it collapses well but is still noticeable. Those who land farther forward will be treated to a soft sole that transitions well off the forefoot. The front features a gradual forefoot rocker with a mild bit of flex that makes for a smooth transition. The forefoot feels best at easier efforts, making this a great mileage shoe and daily trainer. The sole is bouncy enough to handle some uptempo miles, but it does not respond fast enough to be a racing shoe.

For those with neutral mechanics, the Hylo Impact is a great easy day, long run and uptempo shoe base on its transitions and cushioning. The outsole traction is good on most road surfaces but this is not a shoe that shoe be used for any type of rough terrain. The outsole rubber is great and there is only a tiny bit of wear after 20 miles of use in my pair. However, the amount of exposed, soft midsole foam makes it easy for rocks to tear up the bottom. Thus, as long as you stay on road and well groomed dirt, the Hylo Impact does great for training miles. 

Bach: The Hylo Impact is a surprise all-around. The Hyperbolt midsole is a bio-based (a spoonful of sugar as they call it), nitrogen-infused EVA. It is far more soft than you would think a sustainable shoe would be. It is particularly soft out of the box, but I did find the foam to settle over a few miles and find a middle ground between soft and firm, leaning just slightly softer. The On Cloudsurfer is a reasonable comparison here, sole-wise. The shoe feels fairly light on foot, but the midsole is reads best at easy daily training paces. The softer sole doesn't read as much responsive as it does comfortable. I was able to pick up the pace a little, but didn't feel like it was a shoe I could sustain workout efforts in. That being said, it handles daily training really well and was fine for both short and longer easy runs. I tend to be a little more forward of a runner and found the forefoot to be great to land on thanks to its spaciousness. The rearfoot does feel less smooth due to the posterior heel flare.

Out of the box, I was really curious how the very unique outsole design would feel. It does grip well and so far seems very durable after 20 miles. On very flat terrain, the shoe's smooth outsole runs just that, very smoothly; when the terrain was a little uneven or going uphill though, I felt like I was butting up on the third rubber oval that doesn't extend all the way up into the toes. I don't think it is at all a dealbreaker for the shoe, but an observation running a very hilly, uneven sidewalk neighborhood.

The shoe being so comfortable on foot has also been a great walking shoe for those who want a softer sole.


Matt: The Hylo Impact is a neutral shoe. There are no traditional measures of stability. There are sidewalls in the heel, although I did not notice this as the midsole foam is so soft it does not provide much resistance to motion. There is a good amount of midsole flare in the heel with more in the medial than lateral direction. However, the posterior heel flare does cause an early initial contact, which accelerates foot motion forward. For me, combined with a narrowed midfoot and extremely soft midsole, this makes the shoe unstable for me. The midfoot is not stable and the narrowed amount makes my foot hang off the medial side. The forefoot has a good amount of sole flare in both directions and the smooth transition is nice. However, it isn't overly stable or unstable up front. Thus, the Hylo Impact will work best for those with neutral mechanics or are sensitive to stability, but not for those particularly with midfoot stability/guidance needs. 

Bach: While the Hylo Impact is definitely a neutral shoe, the forefoot does have a good amount of width and sole flare that reminded me a little bit of the Puma ForeverRun Nitro. The insole also wraps up slightly around the midfoot which helps you stay a little centered on the platform. For runners who like have that generous forefoot, it does feel nice to land on. The shoe otherwise is very neutral in the mid-to-rearfoot with a narrow medial midfoot and slightly clunky heel. The shoe feels better for runners who are a little bit more forward in their running. For flat foot runners, I felt decently comfortable in the shoe despite the lack of stability and didn't find anything irritated my foot. I did reserve the shoe for slower, easier efforts overall due to the stability in the midfoot.

Culture Corner: Innovating the End-of-Life Space for Running Footwear
By Bach Pham

We talk a lot about the innovations happening around the ride and stability of footwear constantly at Doctors of Running, but something we haven't explored at all is what innovations are happening about the afterlife of a shoe. The sustainability space has been rapidly growing as brands compete to make footwear that both performs and hits sustainability goals. While some companies have focused more on the use of bio-based ingredients within the shoe itself, others like Hylo have also investigated and come up with ideas that complete the cycle. The reality about running shoes is that they create a tremendous amount of difficult-to-breakdown waste. For high mileage runners, one can go through several pairs a year and the shoes have very little that can be done post-running life besides some walking and errands until the sole is completely used out. There are solutions in the works though, and we gathered just a few of the most interesting ideas companies have innovated over the past few years:

Hyloop (Hylo): The Hyloop program allows Hylo runners to send their shoes back to Hylo. Hylo is in fact also taking non-Hylo trainers as well! Learn more at 

Index 03 (Salomon): More focused on their singular model, the Index is a bio-based shoe in the Salomon line-up that runners can send back to Salomon who will dissect the shoe for a second life in ski boots.

EcoPure (Newton Running): Instead of recycling, Newton offers a completely hands-free strategy by adding an additive called EcoPure to their shoes which helps rapidly accelerate the decomposition by 75% when it is in the right conditions (aka a landfill). Newton says shoes can take nearly 40 years to fully decompose. This process would bring it down to 10 years.

Cyclon (On Running): The Cloudneo introduces a monthly subscription-based model where runners can wear down the shoes and return for a new pair every 90 days to six months. The shoes are recycled by On to make new products.


Matt: Overall I am extremely impressed with the Hylo Impact. This is a GIANT step forward for this company while maintaining their mission and is a true performance running shoe. The foam is great, the ride is comfortable, the upper fits decently and the shoe feels like a true maximal training shoe. There is still some room for improvement in the sole geometry and upper. As comfortable as the upper is, I think it is a bit thicker than it needs to be. The heel especially feels a little thick and could be thinned down to save a little bit of weight. The laces are a bit thicker than necessary too and could be thinned out a little. Outside of those things the upper is good.

The midsole cushioning is awesome but that large posterior flare could be reduced to make heel transitions smoother. If this could be cut down a little, it would further save weight and make for a smoother transition. With a 39mm stack height, a large heel bevel is necessary for appropriate transitions, although right now the extremely soft midsole material takes some responsibility off this. While I recognize there are sidewalls, the sole is so soft that any stabilizing mechanism from the sole does not seem to help offset the narrowed midfoot. There is nothing wrong with soft cushioning and this design for those with neutral mechanics, but those with stability needs may struggle with this shoe over longer distances. Give this is a maximal shoe, I would consider filling in the midfoot for a touch more guidance. Outside of that, this is a great shoe and is probably the best bio-based shoes I have ever tried. 

Bach: The Hylo Impact is a massive upgrade for the company and immediately pushes them into a competitive position in the running market with this model. I completely echo Matt on his recommendations. I wouldn't mind just a little bit more volume in the midfoot for added comfort, while snugging in the heel slightly for a more locked-in fit to really let the shoe shine. As a neutral shoe, the underfoot feels solid besides the geometry changes that would help the rearfoot. Continuing to dial in the upper will only help further make the shoe shine.


Matt: The Hylo Impact is for those with neutral mechanics and normal-width feet wanting a highly cushioned, maximal stack height shoe that is completely bio-based. The upper fits normally with a little taper up front and a little extra room in the back. The midsole is extremely cushioned with a little bit of a clunky heel but a smooth forefoot transition. Best as a daily training shoe but with a little versatility into some uptempo miles, the Hylo Impact is a great second shoe for the company, demonstrating how serious they are about footwear while also showcasing what can be done performance-wise with green materials. The $165 price tag is fairly mild given the materials used and the performance provided, appropriately running in line with other brands with similar models. Some refinements are still needed (get rid of that posterior flare!) but this shoe clearly shows that performance can be Earth-friendly. Now the question is... can we have a bio-based super shoe?

Bach: Hylo's transformation from the shoe they started with two years ago to the Impact is nothing short of astronomical. The Impact is a very modern, surprisingly fun bio-based trainer that will tick a lot of boxes for runners who want both a well-forming neutral trainer and sustainability. The shoe is easily in the conversation as a top bio-based, premium cushioned trainer alongside shoes like the Saucony Triumph RFG and slightly bio-based Asics Nimbus 26.

Something we haven't talked about is that the shoe simply looks good. There's a lot of fun design features to the shoe with their signature Run Like the World Depends on It branding around the shoe and clean logo embedded into the upper. It strikes both some minimalism with a little bit of their stamp on the shoe.


Fit: B+ (Slightly thicker upper with normal width fit. Slightly snug in forefoot with a little width in the heel)
B+ (A highly cushioned and comfortable ride that is best for daily training/uptempo miles. Slightly clunky heel transitions into smooth forefoot)
Stability: B/B- [Neutral] (Extremely soft sole and narrow midfoot make this shoe best for neutral mechanics even with sole flare and sidewalls)
Value: B+/A- (Comparable price to other premium cushioned daily trainers)
Personal: B (Extremely comfortable shoe. Not stable enough for me and upper a little thicker than necessary. Need posterior flare removed but otherwise a great shoe that will work well for many people with neutral mechanics)
Overall Design: B/B+ 

Fit: B+ (The shoe has a very relaxed, easy day fit. The shoe runs slightly snug in the forefoot and slightly wide in the heel though which may make some decision-making on sizing a little difficult for some)
B+ (A really cushioned, comfortable ride with a generous forefoot to land on)
Stability: B (A very neutral shoe through and through)
Value: A- (It reads high, but matches spot on with most competitors which is impressive for a heavily bio-based shoe)
Personal: B+ (I'm just really impressed by the changes Hylo has made and can't wait to see more.)
Overall Design: B+


Hylo Impact
Price: $165 at Running Warehouse

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Editor's Note: As always, the views presented on this website belong to myself or the selected few who contribute to these posts. This website should not and does not serve as a replacement for seeking medical care. If you are currently injured or concerned about an injury, please see your local running physical therapist. If you are in the Los Angeles, Santa Barbara, Danbury and Stevens Point areas, we am currently taking clients for running evaluations.

***Disclaimer: These shoes were provided free of charge in exchange for a review.  We thank the people at Hylo Athletic for sending us a pairs.  This in no way affected the honesty of this review. We systematically put each type of shoe through certain runs prior to review. For trainers and performance trainers, we take them on daily runs, workouts, recovery runs and a long run prior to review (often accumulating anywhere from 20-50 miles in the process). For racing flats we ensure that we have completed intervals, a tempo or steady state run as well as a warm-up and cool down in each pair prior to review. This systematic process is to ensure that we have experience with each shoe in a large variety of conditions to provide expansive and thorough reviews for the public and for companies. Our views are based on our extensive history in the footwear industry and years testing and developing footwear. If you are a footwear rep looking for footwear reviews or consultations on development, we are currently looking to partner with companies to assist, discuss and promote footwear models. Partnership will not affect the honesty of our reviews.

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