Tuesday, March 14, 2023

Antepes Muscle Runners Review: Run-focused strength and mobility training can be dull - but not if you get to actually run while doing it!

Article by Mike Postaski

Antepes Muscle Runners ($225)


Mike P: I usually jump at the chance to try out anything in the “natural” running space - but of course the Atepes Muscle Runners really defy any sort of categorization. I was able to try out the Naked T/r shoe this past summer - which I thought was a pretty radical design (no shoelaces). But the Muscle Runners now take the cake in that regard. 

With a 18mm positive heel gain - the forefoot is higher than the heel - they make an immediate and striking impression. Yes, I’ve read some of the comments, even within some of our own internal RTR discussions - “blown out Achilles!”, “torn up calf muscles!”, “tendonitis!”, and the like.. I’m not going to completely give away the conclusion here, but I will give one tidbit - I experienced no ankle, calf, or Achilles irritation when using the Muscle Runners. So what do I think about the shoe overall - does it work? Is it merely a training tool? Can you actually run in them?


Comfortable and stable-landing forefoot Mike P

Sustainable materials - Merino wool/Tencel upper Mike P

Heel lockdown works with low collar Mike P

Strengthens lower leg muscles, helps focus on running form & posture Mike P

Actually runnable at normal paces Mike P


Can feel bulky despite low weight (could be due to unusual weight balance) Mike P

A bit difficult to get into and lace up Mike P

Not sold on if those heel wings actually do anything Mike P

High price (but first orders include a nice massage roller) Mike P


 Sample Weight: men’s 9.7 oz  / 274 g (US 9.5)

Stack Height: men’s 21.5 mm heel / 31.5 mm forefoot 

(Forefoot is dropped 10mm lower than heel inside the shoe. Heel ground clearance is 18mm when the forefoot is level with the ground)

$225 Available now for pre-order at Antepes. 10% off on your total order at the link

First Impressions, Fit and Upper

Mike P: Given the truly unique design, I was initially sent two sizes to try for testing (US 9.5 and 10) - in order to ensure I would have the proper fit and comfort. Antepes recommends to size up if you are between sizes. I found the true-to-size US 9.5 to fit just fine. With an intentionally designed broad forefoot and toebox, and the right amount of space in front of the toes, true-to-size is the way to go in these for me.

The upper is a 100% knit construction made up of sustainable materials - Merino wool & knit eucalyptus tree fiber fabric (Tencel). I’ve had some apparel which utilized a Tencel blend, but this is the first time I’m aware of it being used in a shoe upper. The knit is quite dense, but also comfortable and doesn’t stretch much - at least initially. That should be something to keep an eye on down the road. The upper is knit into a bootie-style design, with no separate tongue. 

This makes the shoe a bit difficult to put on - the top opening is slightly tight and also socks tend to grab on to the knit upper material, especially at the tongue area. Plan on an extra minute or so to lace up and possibly using a shoehorn to make things easier (really not a big deal). With the bootie style design, the lacing uses an over/under pattern for eyelets. This also makes the lacing very secure with little/no slippage. I actually laced them a bit too tight around the forefoot on my first run, and squeezed my foot a bit too much. I loosened them up after that, and found the knit upper substantial enough to hold my foot well.

The heel area features something totally different - the HEELX counter. This is made up of the counter itself at the rear of the heel, connected to those separate arched “wings” extending above the collar. The intention of this design is to make sure the heel is locked down enough, without resorting to using a collar against the Achilles to hold the heel in. The “collar” itself at the Achilles is much lower than a typical collar at the Achilles area, and doesn’t make contact with the Achilles at all.

With the heel itself being either “suspended” in the air, or when touching the ground, in a “reverse drop” situation, you can see how heel lockdown would be a primary concern. Throw a carbon plate in the mix, and you can further imagine the pressure trying to pull the heel out of the shoe. Antepes has done a great job with this - once my foot is set in the shoe properly, with the right amount of lace tension - I don’t have any movement or irritation in my heel. 

Now those extended wings are another issue. I have not felt them on the run at all, and I’m not even quite sure if I’m supposed to be noticing them. Perhaps they provide some type of counterbalancing effect to the lower area of the heel counter? Or perhaps they are there for aesthetics? 

Antepes describes their purpose as follows in an email to RTR:

"The medial (inside) and lateral (outside) tabs of the heel counter limit the stretch and deformity of the fabric behind the heel, this allows for the back of the shoe to be lower behind the heel, and therefore there’ll be less surface resting on the Achilles creating friction, which lowers the chance of irritating the Achilles for some runners. Most running shoes have the back of the heel be 5mm higher than compared to our shoes. The tabs are extended and curved back as to follow the shape of the back of the ankle, moving into the space between the malleolus bones and the Achilles, as to avoid poking the ankle. We also did not want anything rigid resting close to the collar behind the heel and the Achilles, and that’s why we have the HEELX heel counter extensions."

In any case, they have no negative effect, so at a minimum they at least look… interesting. 


Mike P: The specs for the midsole are - 31.5mm under the forefoot, and 21.5mm under the heel. This means MORE cushion under the forefoot (10mm Forefoot Gain as they call it) than the heel. This is the opposite of literally every other shoe out there aside from zero drop. On top of the additional physical cushioning under the forefoot, there is a total 18mm “Heel gain” as they call it. According to specs - this “elevates the heel when the shoe is positioned parallel to the ground”. The website also mentions that the forefoot is positioned 10mm lower than the heel inside the shoe.

The numbers are a bit confusing, but in any case - when standing in the shoe with both the forefoot and heel touching the ground, your foot is slanted appreciably and noticeably upwards from the heel to the toes. 

[I’ve got 18mm of washers stacked under the heel here. If I understand their numbers correctly: 31.5mm forefoot - (21.5mm heel - 10mm forefoot lower inside shoe) = 20mm clearance. They say 18 mm heel ground clearance.. Not sure where the other 2mm goes]

The midsole foam itself is a dual-layer Pebax bland, a bit softer at the top and firmer below. There is also a carbon fiber “ForeSpring Plate” - which is mentioned as being flexible in the forefoot and more rigid under the arch and heel. With such a high forefoot stack at 31.5mm, I was initially surprised that the shoe wasn’t softer. I typically think of Pebax as being lighter and usually a bit bouncy, but there’s none of that here. It’s a firm, but not hard blend, with only a little bit of give from the softer upper layer. 

[Here the position on flat “ground”]

After a few runs, this made sense to me, as you’re primarily landing and “balancing” on the forefoot area. Any mushiness or softness would likely be quite hazardous to your ankles in that position. Remember you have no inherent stability coming from the midfoot or heel area. The denseness and stability of the foam works well with the wide landing area so you can really focus on your own balance and form versus having to worry about additional instability coming from the shoe itself. 

The carbon fiber plate is another element which aids in the overall stability package - I’ll discuss that in the Ride section below.


Mike P: Less details are given about the outsole outside of saying that it’s a natural rubber blend. I find it to be on the softer side and grippy enough for wet conditions. There’s obviously no need for any coverage around the midfoot area, and only small areas near the heel touchdown area. There are two segments in the broad forefoot landing area - perhaps the segmentation helps to smooth out the landing from the lateral impact through to the medial side. It seems to work well as I don’t notice any slappy-ness, even though the forefoot is quite wide. I detect a rhythmic “padding” sound when running in the shoe, which is pleasing. 


Mike P: Onto the crux of it.. What is this shoe for? Is it a training tool - to be used in small doses here and there? Is it a legitimate running shoe? Can you run in them on a daily basis? Should you be scared of them, etc. etc. ? 

I was so intrigued that I took them out for a test run as soon as I got them. But given that they looked so radical, I restricted myself to only 5 minutes of feeling out, then 10 minutes of actual running. First off - I almost tripped down my front steps walking out the door. I guess my muscle memory/brain was a bit thrown off by the lack of heel - kind of like when you’re going down the stairs not paying attention and you somehow think there’s another step when you’re already at the bottom. So, keep in mind - pay attention initially to uneven surfaces, stairs, curbs (!) etc. 

On my first run, I wasn’t quite sure if I should be forcing my heel to touch the ground or not. I assumed that I should, so I was actually forcing myself to do it, and it felt a bit strange. There’s a bit of a noticeable tipping point between the back of the ball of the foot and the midfoot. I felt myself landing in that area a bit too much when forcing myself to try to touch the heel down. I did feel some slight pulling around my mid-calf, but I hadn’t warmed up at all. To be fair - Antepes gives very clear guidance that it’s best to warm up a bit, stretch the calves, maybe even do a bit of rolling. 

On subsequent runs, I followed their advice and did some minor light stretching, foam rolling a few times, and some different calf raises and ankle rotation movements. Not a lot, maybe 5-10 mins or so, but it definitely helped. I of course felt much looser right away from the start of my runs in them. Also, on my next runs I didn’t force a heel touchdown. I more or less tried to run on the forefoot and tried to find my balance without the heel touching the ground. 

Interestingly, Antepes guidance suggests to let the heel touch down at first, then work your way up to keeping the heel up when it’s comfortable. For me, I felt the heel touch down to be awkward. I found not forcing the heel to touch down much more comfortable and my running was much smoother. I’m already a midfoot/forefoot striker to begin with, so perhaps your running style will dictate what feels best.

I was able to do 20-30 minute runs with ease - even hitting my normal easy run pace (around 8:00-8:30/mi) without thinking about it. I expected that I would be running much slower and more deliberately in them, but that wasn’t the case at all. Also I was quite surprised that as I got up to 30 minute runs, I didn’t have any ankle, Achilles, calf pains or tightness at all during the runs. 

When we think of carbon plates in running shoes these days - we think of them in terms of their lever effect leading to propulsion. I don’t think that’s quite the case here. It was explained to us that the plate prevents the ball of the foot from sinking down too much and thus putting too much pressure on the toes. My feeling is that the plate acts more as a cantilever - supporting the foot when the heel is in the elevated (“hanging”) position. I suppose it makes sense that without the rigid support of the plate, and with the absence of midfoot or heel contact, the toes would be put under more pressure.

Years ago I did deal with a bout of Achilles tendonitis in my right ankle when I was primarily road running, so I’m aware of how it feels, and what to look out for. My right ankle also has a little bit more instability than my left. Sometimes I can get mild irritation around my lower ankle tendons if a shoe is some combination of being too soft, unstable, or twisting the foot in an uncomfortable way.

With the Muscle Runners, I feel even MORE stable than some other running shoes. On one hand that doesn’t seem to make sense, but if you really think about it - there’s no heel or midfoot interference to “throw” or twist your foot/ankle in a particular direction that it may not want to go. You’re simply relying on your own foot/ankle/Achilles/lower leg/calf/(and on up the chain) to stabilize yourself. After all, the #1 exercise for Achilles rehab is eccentric heel drops.. Is the ride of the Muscles Runners any different?

Conclusions and Recommendations

Mike P: I’ve gotten up to runs in the 30+ minute range in the Muscle Runners, and that feels about right for me right now. I followed their advice and ramped up slowly and cautiously, even though I do have experience with running and using more “natural”, and zero drop running shoes. I did experience some residual, light soreness in my calves after a couple of my runs, but not after all of my runs. I’m also training consistently, so definitely some of that affect may be caused by general tightness from my regular training. 

I’d absolutely caution anyone that has no experience with a zero drop, or natural running style shoe to ramp up even more cautiously with the Muscle Runners. If that’s your situation, I’d advise you to view them more as a “tool” than a running shoe, at least initially. Furthermore, if you’re a definitive heel striker, I’d recommend following that advice x 10. Perhaps experiment with midfoot/forefoot strike patterns in a more familiar low or zero drop shoe first.

For those that are experienced and interested (and if you have that type of $$$ to spare), I think they can be a useful tool for enhancing your running. I see them as a mix of strength, prehab, and actual run training all rolled into one. I like to mix them in here and there when I have a short bit of time to spare, and my legs are feeling fresh. 

The innovative aspect of the raised heel, reducing midfoot/heel interference underfoot - really does put the emphasis on form, balance, and supporting lower leg strength. All aspects of the shoe work well to support that intention - wide & stable forefoot, firm and not too soft cushion, supportive knit upper with no Achilles irritation, carbon plate for foot support. To get those types of form, balance, and lower leg strength improvements, you typically have to focus on very specific (and usually non-running) exercises. Run-focused strength and mobility training can be dull - but not if you get to actually run while doing it!

[Antepes has a limited supply of their Fascia Crusher massage rollers that will be provided with the first orders. I really like the roller because it’s so big and I can get more pressure when rolling out my calves and legs. You can see how it dwarfs my current TriggerPoint roller. If you’re on the fence about the cost of the shoe, it’s definitely a good value add-on]

This is a tricky shoe to score, so take these scores in a context of their own. Don’t think of the actual numbers in relation to other standard running shoe scores. Scoring is less relevant in this shoe specifically since it is so different.

Mike P’s Score:  8.7/10

Ride: 9 - Stable, firm and supportive, surprisingly easy to hold a regular running pace . Stability is key in allowing the shoe to do what it’s supposed to do.

Fit: 9 - Nice, wide forefoot for stability, knit upper holds well. No heel slip for me.

Value: 7 - It’s a high price, but expected for a unique, “concept”-type shoe. Most standard shoes are pushing $150+ these days anyway. Note - if the price is not an issue for you, the shoe scores a solid 9 across the board. Also, the massage roller is included in the first orders.

Style: 9 - The blue looks just like it’s name - Hawaii Ocean, All white looks slick too

Smiles: 😊😊😊😊


Index to all RTR reviews: HERE

Mike P: There are no true “comps” for the Antepes Muscle Runners. Just throwing a few natural or zero drop options out below to highlight some features and differences. None of the comps have any sort of “Heel Gain”, so take that as a given as far as the comparisons go.

Skora Fit (RTR Review)

Mike P (10.0): A shoe I recently tested which I found interesting in the “natural” running space. It takes a more cushioned approach as opposed to the traditional very thin soled design (see Vapor Glove below). This is similar to the Antepes in that neither shoe focuses on “feeling the ground”. Also unique to the Skora is that it features a raised, rounded heel area under the center of the heel. The idea again is also similar to the Antepes, but done in a different way. The intention is to limit any interference from a blocky heel, and to allow the heel to touch down at a more natural angle (whatever that may be for your running pattern). I do wonder if the designers of the Muscle Runners considered this type of design - having a smaller, more narrow, and centered heel. I’m not sure if it would work though as the Antepes is more rigid by nature while the Skora is truly flexible and even foldable.

Merrell Vapor Glove 3 

Mike P (9.5): I’ve been doing all of my treadmill run/hikes recently in these. It’s your more standard, no cushion, “outsole only” natural running design. I like them on the treadmill because I don’t have to worry about running on hard ground with them. It feels like I get a bit of a foot workout too, especially when I’m doing incline hiking. I like that the Vapor Gloves because the rubber outsole wraps up a bit on the medial side, which gives a slight bit of support underfoot.

Topo Magnifly (RTR Review)

Mike P (9.5): This is your more standard zero-drop running shoe in a more traditional style. All the elements of a regular running shoe such as cushion and a more familiar ground platform, mixed with elements of a natural running shoe - namely zero drop and a wider toebox. Topo is a great option in this space as they have great midfoot lockdown, wide but not overly sloppy toeboxes, and good cushion - especially in their newer Zipfoam V2 models.

The Muscle Runner is available now HERE
10% off on your total order by using the link above

Mike Postaski currently focuses on long mountainous ultras - anywhere from 50K up to his favorite - 100M. 5'10", 138 lbs, midfoot/forefoot striker - he typically averages 70 mpw (mostly on trails), ramping up to nearly 100 mpw during race buildups. A recent 2:39 road marathoner, his easy running pace ranges from 7:30 - 9:00/mi. In 2022 Mike won both the Standhope 100M and IMTUF 100M trail ultras within a 7 week period - both extremely rugged Idaho mountain races. Mike's shoe preferences lean towards firmer, dense cushioning, and shoes with narrower profiles. He prefers extra forefoot space, especially for long ultras, and he strongly dislikes pointy toe boxes.

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