As I first mentioned in my review of the original Altra Instinct, the first thing most people notice about any of the shoes in the Altra line is the foot shaped design. This feature alone sets Altra apart from most of their peers. The distinctive toe box follows the shape of the foot and allows plenty of room for your toes to splay naturally. The Altra Instinct 1.5 skirts the boundary of the minimalist running shoe category. The Instinct 1.5 is definitely minimal because of its zero heel-to-toe drop and anatomically correct shape (custom for women and men) resulting in a nice wide toe box for proper toe splay and the weight is a modest 8.9 oz (252 gr) which is .1 oz (3gr) heavier than the original Instincts. The total stack height is 22.5-24.5mm depending on which removable foam insole is used; either the 5mm Sculpted or 3mm Strengthen insole. The remaining stack height comes from the 15mm thick Dual Layer EVA with A-Bound Top Layer midsole and the 4.5mm thick FootPod Outsole. Obviously with this relatively thick stack height, the amount of ground feel or proprioception is somewhat limited. The new Altra Instinct 1.5 besides being unnoticeably (though slightly) heavier than the original has had its upper completely redesigned and in my own opinion is at least cosmetically and visually superior to its predecessor. Read on for more photos and a full review!

The Upper

As can be seen in these photographs the Instinct 1.5 upper is radically different than the original. What was previously a very large open weave mesh material has been enhanced with an additional filament mesh layer to help keep out debris and dust. The two layer upper approach I found to be very similar to the Saucony Kinvara2 uppers that employed a similar technology. I found these uppers to still be extremely breathable and a lot more stylish than the original Instinct uppers. In addition to the asymmetric lacing, the Instinct 1.5 utilizes what Altra calls the ‘A’-Wrap (the gray strips at the midfoot) and the HeelClaw™ (gray strips in the heel) to lock your heel and midfoot into the shoe while still allowing ample toe room. A nice feature of the entire Altra line is the minimization of seams. I can’t evaluate how these shoes would handle running sockless, but I’ve encountered no foot discomfort: abrasions, blisters, etc… even with the thin socks I wear. All the Altra line comes with removable, thin foam footbeds. There is absolutely no arch support in the Instinct 1.5, the foot bed of the shoe is completely flat and shaped like your foot. So w/o an insole there will be a void between the top of your arch and the food bed. So if you want to “fill that void” use one of the provided foam insoles. The Instinct 1.5, along with all the other Altra models, is designed gender specific to accommodate the unique female and male foot forms. In general this means that the female version, called the Intuition, runs narrower in the heel than the male version and the toe box of the female is a bit narrower than the mens. Overall my first impressions were very positive. Before running in Altra running shoes I’d been so used to slipping my feet into typical road running shoes that ended up crowding my toes together; not so with the Instinct 1.5. I think the large open weave mesh will help keep my feet cool during the swelteringly humid summers where I live. Can’t really highlight any obvious flaws with the new upper other than perhaps the dual layer might make the shoe less breathable? I didn’t find this to be the case but could see why this might be so.

The midsole

The midsole of the Instinct 1.5 is exactly the same as the original Instinct which consists of two sandwiched layers. The first layer, immediately below the footbed is what Altra calls A-Bound™ which they describe as an:
Environmentally friendly, this energy-return compound is made of recycled materials. Offering extra protection, this unique layer sits directly under the foot to return energy back into each stride. It reduces the impact of hard surfaces while still maintaining ground feedback. Traditional running shoe foam compresses 70-90% while A-Bound™ compresses 2-3x less so it won’t deform over time.
The second layer is rather stiff EVA foam, more of the A-Bound™ material but slightly firmer than the first thin layer. If you’re thinking this is a “cushy” road shoe you’d be surprised to learn that the Instinct 1.5 midsole is far from it. In fact the overall feel is very firm and ground feel, while much reduced, isn’t completely eliminated. I could still notice gravel and road inconsistencies underfoot but the relative thickness of the midsole definitely was doing its job to protect my feet.


The sole

Altra calls it the FootPod™ Outsole and it is indeed one of the most unique road sole designs I’ve ever encountered. The skeleton looking sole is also another conversation starter. Per Altra, this outsole was designed “For maximum flex and responsiveness, this outsole maps the bones and tendons of the human foot. With canted lugs mapping your foot, this unique outsole provides a natural, all-purpose traction system for a variety of surfaces from road to treadmill to dirt paths.” I can attest that the outsole is adequate for running on most dry surfaces even on some buffer trails I felt comfortable and in control with the simple tread pattern. Now wet and muddy trails would be a different story, but as this is primarily a road running shoe it’s no big deal. I had more than a few wet pavement runs with these shoes and they definitely don’t slip!


As of this review I have tested the Altra Instinct 1.5 running on paved and gravel roads, on easy dry trails and even on a rubberized track. In short, I’ve tested these shoes on most surfaces it was intended for. At the time of this review I’ve logged almost 50 miles in these shoes and here are my impressions: Pavement — Simply superb; what this shoe is designed for. Plenty of traction and the firm cushioning is neither too squishy nor bricklike. Most of my mileage in the Instinct 1.5 has been on pavement or concrete and I can say they’ve performed very effectively. I did notice on a few occasions when I ran on wet pavement that I did feel the sole slip some which was cause for some concern. Gravel — Very effective. While I could notice larger chunks of gravel I stepped on (sometimes purposefully just to see) it definitely was muted and not painful. For normal gravel I still could sense the ground so there is some ground feel transmitted due to the hard rubber sole and firm midsole. One very slightly annoying thing about running on gravel is the possibility of getting a small rock embedded in one of the grooves on the bottom of the shoe. Didn’t happen super often, but it happened enough to mention but this rock collection capability is definitely not unique to this shoe! Non-Technical Trails — Definitely adequate. A lot of my evening runs with my spouse are on a wooded trail behind our home; never had any issues. The lower profile (stack height) is a plus on the trails. I even ran some on these same trails in less than favorable conditions, mud, standing water, etc… and they still did surprisingly well; slippage was kept to a minimum; definitely better than some other trail dedicated shoes I’ve worn! I never tried the Instinct 1.5s on some of my more “hard core” routes, but I’d suspect they’d do just fine; probably better in drier conditions. I wouldn’t hesitate to use the Instinct 1.5 as a go-to hybrid road/trail shoe for races or routes that would require such a shoe. Rubberized Trac — Not a whole lot of running here, just a weekly speed session on a local track. As expected the Instinct 1.5 worked just fine, but then again about any shoe will work well on a cushy rubber track! However, it’s good to know there weren’t any obvious flaws.


After about 50 miles in the Instinct 1.5s I can’t notice any significant wear in the either the uppers or the sole; even the midsole hardly seems compressed to any degree. Obviously 50 miles shouldn’t be enough to notice any significant wear but it should be enough to spot any major design flaws. In short the Instinct 1.5 is a nice upgrade to the original Instinct. If you liked the original Instinct you’ll love the new 1.5 even more. The overall fit is superb and my toes have never been happier having plenty of room to splay! If you’re an avid runner who is dabbling in (or thought about it) minimalism but doesn’t want to sacrifice ample underfoot cushioning this is the shoe for you. Or even if you’re not a runner but want a shoe with ample toe room that fits well, this is the shoe for you. Note that they retail for $100 but if you don’t mind the older styling, LeftLane has the original Instincts for $55 (and if you’re not a member, use this invite to join and get $10 credit to use on your order). The fact that it’s zero drop, has enough firm cushioning without going over board and has an ample toe box that allows natural toe splay should be enough! Try it out, you’ll like it! As far as my own critical feedback I’d just have to add that it would be nice if the Instinct 1.5 was a bit more flexible in the forefoot and a bit lighter. I think that with some cosmetic and material changes the shoe could be made significantly lighter. Another way to make this shoe radically lighter AND increase its flexibility would be to reduce the amount of the 4.5mm thick FootPod Outsole material. If this shoe was redesigned to only cover the most likely wear pattern areas (midfoot, toes, heel) with the high friction rubber and leave the rest of shoe exposed to the foam midsole you’d most likely shave a lot of weight and make the shoe more flexible as a result. It’s the lack of flexibility that is my only serious criticism of the “thicker” Altra line of shoes. Note that I started running a lot of miles in more flexible though adequately cushioned and roomy shoes a few months ago (Skechers GO line) I’ve been hooked and really noticed the lack of flexibility in these Instinct 1.5s so much more than when I reviewed the original Instincts. This may amount to more of a personal preference but I’ve also noticed a flexible shoe is a quiet shoe and there is something to be said for quiet footsteps …

Altra Instinct 1.5 Specs

Straight from Altra:
An upgrade from the original award-winning shoe, The Instinct™ is the first shoe to truly marry the form-improving benefits of a minimalist shoe with the comfort, cushioning and support of a traditional running shoe. The Zero Drop™ platform and innovative foot-shaped design work together to help runners maintain proper running technique and reduce joint impact while freeing their toes to help alleviate foot pain. Trust your instincts and experience the world’s first fully cushioned, foot-shaped, Zero Drop™ running shoe.