Nike ZoomX Invincible Run Flyknit 2: One of Us Actually Likes It
By Contributor Andrea Myers
The Nike ZoomX Invincible Run 2 is a premium daily trainer with a bouncy, cushioned ride from its thick ZoomX midsole and unique geometry. It has a distinctive look thanks to its wide rearfoot and forefoot sole flare in combination with a heavily rockered sole. It is mostly unchanged from the original version, with some updates to the laces and upper. I was interested to find out what this much ZoomX would feel like without a plate; I found a bouncy, responsive shoe that I have greatly enjoyed for easy runs.
Price: $180 at Running Warehouse
Weight: 11.07oz, 314g (men's size 9), 8.92oz, 253g (women's size 8)
Stack Height: Men's: 36.6mm/27.6mm Women's: 34.2mm/25.8mm
Drop: Men's: 9mm Women's: 8.4mm
Classification: Max cushioned premium trainer
RUNNING SHOE SUMMARY
The Nike ZoomX Invincible Run 2 is a premium daily trainer for those who love the bounce of ZoomX (the foam used in the Vaporfly and Alphafly). The shoe does not have a plate, so it relies on its unique geometry to stabilize its thick ZoomX midsole. The most noticeable feature of the shoe is the extremely wide sole flare in the heel and to a slightly lesser degree in the forefoot. The rearfoot sole flare combined with a significant heel bevel made our founder, Matt Klein, return version 1 last year due to Achilles pain (Check out his video review here: https://youtu.be/Hox9ia3LIco). We emphasize here at Doctors of Running the fact just because a shoe does (or doesn't) work for one person, it might perform differently for someone else. One thing Matt mentioned in his video is that while the shoe didn't work for him as a heel striker, the geometry might work better for midfoot strikers like myself. I found Matt's prediction to be spot on and I have really enjoyed testing the cushioned and responsive Invincible Run 2 on many easy runs.
SIMILAR SHOES: New Balance Fresh Foam X More v4
FIT
The Nike ZoomX Invincible Run fit a little long in my usual women's 9.5, but not so much that I would have gone down 1/2 size. This shoe had high step-in comfort for me. I really like the wide toe box, which allows for some toe splay without allowing medial-lateral foot translation. The midfoot narrows significantly, similar to the original Alphafly, and then widens to a normal to slightly wide rearfoot. There is some medial arch support built into the midsole, which feels similar to, but a little less intrusive, than the React Infinity Run FK 3. There is a rigid external heel clip that extends almost to the midfoot on the medial and lateral sides. The heel collar is lightly padded and is unusual in that the padding extends forward towards the malleoli (ankle bones). I occasionally noticed some rubbing on my inner ankle bone, but overall found the fit of the rearfoot to be comfortable and secure. The gusseted tongue is padded and stays in place well. The FlyKnit upper is thick and not the most breathable, but it was perfect for the fall weather (40s-60s) here in CT. The laces are thick and a little cheap feeling for a $180 shoe, but I didn't have any issues with lockdown. I do not run sockless, but there are some interior stitches around the gusset that may cause irritation on bare skin.
PERFORMANCE
I was pleasantly surprised by the feel of the Invincible Run 2. Without a plate to stabilize the thick ZoomX midsole, I anticipated a marshmallowy, unstable ride. Instead, I found a midsole that is bouncy and responsive, while unquestionably softer as compared to Nike's plated ZoomX offerings. I am in the middle of marathon training, and my feet are definitely looking for some cushion and protection on my easy runs.
The rocker geometry of the Invincible Run 2 greatly influences its performance. Due to the severe rearfoot sole flare and heel bevel, heel strikers may experience an entirely different feeling shoe as compared to runners who land further forward. As a midfoot striker who lands at the lateral midfoot, I really had no awareness of the rearfoot geometry while running. I found the wide base, forefoot sole flare, and forefoot rocker to allow me to land comfortably at the lateral midfoot and to allow a smooth progression to push off. At initial contact, the midsole compresses without bottoming out, then immediately returns the energy to boost you into push off. The best metaphor I can use for this feeling is the bounce of a kickball from grade school gym class. The Invincible Run 2 does not have the same propulsive feel that the Vaporfly and Alphafly do, which is likely due to the lack of a plate, different rocker geometry, and heavier weight.
I mostly used the Invincible Run 2 for easy runs, but I did use it for a workout that included 12x20 second strides in the middle. While it wouldn't be one of my top choices for faster running, I found it could handle short bursts of sub-5:30 pace without feeling clunky or unstable. I have used it on easy runs up to 90 minutes and used it for a 4 mile cooldown at the end of an 18 mile workout. This could potentially be an easy long run shoe for some runners.
The heel bevel makes it feel a little less than its stated 8.4mm drop for me, but heel strikers may experience the drop differently due to the large rearfoot sole flare and heel bevel. The waffle-patterned full length rubber outsole provides excellent traction on wet roads and dirt. I have 45 miles on my pair and there is minimal wear at the lateral midfoot. I would expect better than average durability from the outsole, but I do wonder how long the ZoomX will maintain its cushion and bounce. Overall, I found the Invincible Run 2 to be a highly cushioned, protective, and bouncy option for easy runs. The shoe has definitely found its place in my regular rotation.
STABILITY
The extreme sole flare, highly rockered geometry, and rigid heel clip provide some stability to a shoe that might otherwise be quite unstable due to the thick ZoomX midsole and narrow midfoot. A common feature of max cushioned shoes is rocker geometry, which helps stabilize the large volume of foam. The Invincible Run 2 uses both a heel bevel and forefoot rocker to guide initial contact to push off. The specific rocker geometry worked for me as a midfoot striker, but the large posterior flare combined with the heel bevel may actually feel destabilizing to heel strikers (as was Matt's experience with v1). The wide sole flare in the forefoot may also help to center the foot from mid stance to push off and reduce or prevent excessive motion medially or laterally. The forefoot sole flare is biased medially, which may help to reduce excessive or early loading of the medial forefoot. I found the rigid heel clip to be comfortable and helped with the overall stability of the upper, but some runners who are sensitive to rigid heel counters may have a different experience. Overall, I found these features in the Invincible Run 2 to work well for my mechanics and contributed to a comfortable and smooth ride.
THOUGHTS AS A DPT / FOOTWEAR SCIENCE
Thoughts on Footstrikes
The vast majority of runners are heel strikers, with many studies stating as high as 93% (Burke et al 2021, Kasmer et al 2013). It is logical that most running shoes are designed for heel strikers due to this statistic. The remaining 10% (including myself) land further forward, either at the midfoot or forefoot. What features should we look for in a running shoe?
The Invincible Run 2 is a great example of a shoe that performs very differently depending where you make initial contact. Matt found that the large posterior flare and heel bevel made rearfoot landings feel unstable and resulted in both Achilles and anterior knee pain. Conversely, I found that the heel bevel made midfoot landings feel natural and not at all unstable. Shoes with a large heel bevel may generally work well for midfoot strikers because the shape encourages a more forward landing. The bevel essentially gets the heel of the shoe out of the way. This is seen in Skechers' MStrike design, the Hoka Meta Rocker, and the New Balance More v4 (among others).
Shoes with a lower heel to forefoot drop tend to work better for midfoot and forefoot strikers, because they allow initial contact to occur with the ankle in less dorsiflexion and therefore a more forward landing. I have found that shoes with 4-6mm drop work best for my mechanics, but I have tested many 8mm drop shoes that are just as comfortable (including the Invincible Run 2), and even found the 13mm drop Asics Nimbus Lite 3 to work for me. Drop is not the defining performance feature of a shoe because the geometry and compliance of the midsole will also influence how the shoe performs.
A wider base at the midfoot and forefoot may also be beneficial for runners who land further forward. Some shoes narrow significantly at the midfoot, and if that happens to be where you prefer to land, it could make initial contact feel unstable. While the Invincible Run 2 does narrow in the midfoot, the posterior aspect of the forefoot is wider laterally, which corresponds to where I land. Most of the shoes that I prefer have a wider base in the midfoot and forefoot, including the New Balance Beacon v3 and More v4, the Saucony Endorphin Pro 3, and the Topo Specter. The Nimbus Lite 3 has a wide base that runs the entire length of the shoe, and is likely one of the factors that makes its 13mm drop work for me.
Of course, running shoe choice is personal and is influenced by a variety of factors, including overall comfort and an individual runner's preferred movement pathway. The shoes that work for me as a midfoot striker may not work for another runner who has a similar strike pattern but different overall lower extremity biomechanics. It may be helpful for runners of all strike patterns to become familiar with the key features of shoes that they like, because it can help narrow down future shoe choices.
Sources
Burke, A., Dillon, S., O'Connor, S., Whyte, E. F., Gore, S., & Moran, K. A. (2021). Risk Factors for Injuries in Runners: A Systematic Review of Foot Strike Technique and Its Classification at Impact. Orthopaedic journal of sports medicine, 9(9), 23259671211020283.
Kasmer, M. E., Liu, X. C., Roberts, K. G., & Valadao, J. M. (2013). Foot-strike pattern and performance in a marathon. International journal of sports physiology and performance, 8(3), 286–292.
RECOMMENDATIONS
The Invincible Run 2 may be a great option for midfoot or forefoot strikers, but may not work as well for rearfoot strikers due to the large posterior flare and heel bevel. The vast majority of runners are heel strikers, so if Nike wants to make this shoe more accessible to those runners, they may want to clean up the rearfoot by reducing the posterior flare and widening the midfoot to promote stability from initial contact to mid stance. From my perspective, the main improvement to the shoe would be the upper. The material does not feel like the upper of a $180 shoe and would likely be hot in the summer. I would recommend making the upper lighter and more breathable to really make this shoe worth its price tag.
WHO THIS SHOE IS FOR
The Nike ZoomX Invincible Run 2 is a great easy day shoe with the cushion and bounce that so many of us love from ZoomX. The geometry of the shoe may make it work better for midfoot and forefoot strikers who do not have significant stability needs. Runners who prefer the Vaporfly or Alphafly for racing may find an ideal easy day training companion in the Invincible Run 2.
GRADING
Andrea
Fit: A (wide toe box, a little extra length, and excellent lockdown make this a well-fitting shoe)
Performance: A- (ZoomX without a plate is still bouncy, protective, and cushioned. Great for easy days, but not the right choice for faster runs)
Stability: B+ (Rocker geometry, sole flare, and secure heel help stabilize a shoe with the potential to be very unstable)
DPT/Footwear Science: B+ (geometry of the shoe is great for midfoot/forefoot strikers, but potentially less stable for heel strikers)
Personal: A- (One of my current favorites for easy runs, but would like a more breathable upper for summer running)
Overall: A-
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FURTHER READING
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New Balance Fresh Foam More v4 - A stable neutral max cushion trainer for long, easy days
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Newton Motion+ - A light, snappy stability performance trainer
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