Physical Therapists Using Clinical Analysis To Discuss The Art And Science Behind Running and The Stuff We Put On Our Feet

Post Page Advertisement [Top]

 


Nike React Infinity Run Flyknit 3: Matt Likes This One!?
By Chief Editor Matt Klein and Contributor Andrea Myers

I (Matt) have a weird relationship with the Nike Infinity Run series. The first version did not agree with my mechanics and I was quite upset about some of the claims Nike made about this shoe preventing injuries. Anyone with a decent understand of methodology understood that having a group of runners with neutral mechanics run in both the Structure, a previously rigid stability shoe, and the Infinity React, a neutral but guidance-based shoe, will do better in the latter. That doesn't translate to less injuries in the general population, it means that half the group was given the wrong shoe for their mechanics. I hated the original, returned it and never reviewed it. So when a pair showed up through Running Warehouse, I was prepared to be disappointed. Instead, I was pleasantly surprised. The upper fits far better, the React foam has been tuned to provide a cushioned ride, the rocker is extremely smooth and several methods of natural guidance have been integrated well. I am actually excited to review this shoe after some great miles, but I still have some comments. 

Price: $159.95 at Running Warehouse
Weight: 10.5 oz, 297 g (men's size 9), oz, g  (women's size 8)

Stack Height: 34mm/26mm
Drop: 8 mm
Classification: Daily Mileage / Recovery Shoe


RUNNING SHOE SUMMARY

Matt: The Nike React Infinity Run Flyknit 3 is a well-cushioned, snug-fitting and rockered mileage/recovery run shoe. A full knit upper with a tongue integrated into the upper sits up top, providing a snug and secure fit, particularly in the forefoot. The full-length React foam provides a plush ride once it breaks in, which combined with the rockered sole makes for solid transitions during easier paces. A heel clip and outsole flare make this a shoe with rearfoot guidance, but this is not a stability shoe. This all makes the Nike React Infinity Run Flyknit 3 best for those with normal to narrow feet wanting a cushioned and rockered shoe for easy and long runs.

Andrea: The Nike React Infinity Run Flyknit 3 is a great easy day shoe once it breaks in. I have never had a running shoe break in as much as this shoe - the arch and heel clip were so intrusive during my first run that I wasn't sure I was going to be able to continue testing the shoe. I am glad that I gave the shoe another chance, because it got better with every subsequent run. The arch and heel clip felt like they molded to my foot with each additional run and the result is a shoe that fits like a glove. I really enjoyed the combination of the React foam and the rockered sole, which give the shoe a pleasant and protective ride. 




FIT 

Matt: The Nike React Infinity Run Flyknit 3 fits me slightly short in my normal US men's size 10. The upper is made of full-length Flyknit mesh, making for a sock-like feel and fit. The upper is normal to snug in width, with a significant taper at the forefoot. This makes the shoe feel slightly short, but the upper does stretch to accommodate the foot. This provides a surprisingly secure fit, so those wanting a closer fit in the forefoot will enjoy this. Those that are between sizes will definitely want to try this on first before purchase and may want to consider a half size up. I personally would stay true to size as I have gotten used to the snugger fit and the upper has adapted to my feet. Like the forefoot, the heel is a bit snugger. A somewhat flexible heel counter sits in the rear, but the heel collar is highly padded, enough that I did not notice it. The counter integrates with the heel clip that encircles the rearfoot. I did not notice this in regards to fit outside of the heel having excellent lockdown. I did not have to lace lock the shoe at all. Two-thirds of the tongue is integrated with the upper. The last third floats freely and I did have some slippage side to side if I did not lock it down. The midfoot fits normal, but the upper in this area responds well to loosening or tightening the laces. I did have to tighten them down to get a better fit and they stay quite secure. Despite the knit upper, I would run with socks in this shoe as the internal Flyknit was scratchy against my skin. As long as you have socks, the Nike React Infinity Run Flyknit 3 provides a snugger, sock-like and secure fit up top.

Andrea: The Nike React Infinity Run Flyknit 3 fits a little snug in my usual women's 9.5. The width is normal, but my big toe is right at the edge of the mesh. Fortunately, the mesh stretches and I did not have any toenail issues due to the shoe fitting slightly small. If I were purchasing the shoe, I would go up 1/2 size (as I do in the Saucony Endorphin line). On my first run, I found the arch support to be very pronounced to the point where it felt like my heel was sitting high in the heel counter. On each subsequent run, it felt like the arch broke in to allow my rearfoot to settle into the heel counter, which resulted in a snug, comfortable fit. By my fourth run, the shoes fit like a glove and I am very comfortable doing easy miles in them. The heel clip makes the lower part of the heel counter rigid, but the upper portion of the heel counter has some flexibility, which makes it feel like it conforms to my calcaneus. Overall, I found the rearfoot to be secure without any pressure points or irritation. The Flyknit stretches to accommodate the foot, but not so much that there is any translation of the foot in the shoe. The laces are a little on the short side, but I did not have to replace them to get sufficient lockdown. The partially gusseted tongue stays in place as long as I tuck the edges of the tongue inside the upper, as it has a tendency to ride over the side of the upper when donning the shoe. 





PERFORMANCE 

Matt: The Nike React Infinity Run Flynit 3 features full-length React foam and works best for easy mileage. The ride is rockered with a significant heel bevel and toe spring. The midsole initially felt dead but became softer and slightly bouncy after a few miles. The rockered transition, softer ride and slight bounce make it best for recovery runs, easy runs and long runs. It is not best for fast runs as the foam does not respond quick enough during high speeds, the rocker works better for easier runs and the trainer-like weight makes it feel clunky when attempting to pick up the pace. While we do not yet have full specs for this shoe, the previous version has a listed 8mm drop. This feels fairly close and the heel is not obtrusive at all given the softer foam and highly rockered midsole. The outsole features full-length durable rubber that provides solid traction on both wet and dry road. While the Infinity Run 3 can handle well-groomed and non-technical trails, it is best for road surfaces. The outsole is extremely durable as I have close to 40 miles on my pair without any sign of wear. Thus, I expect an above-average number of miles out of these. For those looking for a rockered, durable and softer ride, the Nike React Infinity Run Flyknit 3 may fit the bill.

Andrea:
The Nike React Infinity Run Flyknit 3 is an ideal easy day shoe. The heel bevel and toe spring contribute to a smooth ride and the non-traditional stability features (heel clip, higher arch support, sock-like fit of the upper) provide support for tired feet. Due to the higher weight of the shoe, I would not use it for faster efforts or even strides. I really like that the thick React foam provides ample cushioning without feeling like a marshmallow. This could be a great easy long run shoe, but I would want to go 1/2 size up to avoid any discomfort that might result from foot swelling on a longer run. My longest runs in the shoe were 1 hour and I had no discomfort whatsoever. The full length rubber outsole provides excellent traction and durability. After 40 miles, there is no visible wear of the outsole. I would expect them to be above average in durability. 




STABILITY 

Matt: The Nike React Infinity Run Flyknit 3 is a stable neutral shoe and borderline mild stability shoe for those that need rearfoot stability. The heel is quite stable thanks to the heel clip, mild sidewalls and well-placed outsole flare combined with the heel rocker. This provides a centered ride that does not push you in either direction. The midfoot is less stable as the sole narrows quite aggressively. The mild sidewalls compensate slightly for this, but those with higher stability needs in the middle of the shoe will need to look elsewhere. The forefoot is stable for the same reasons most maximal shoes are in the forefoot. There is a significant amount of flare on both sides of the front sole and the rocker roles you forward efficiently. Overall the Infinity Run 3 will work best for those with neutral mechanics wanting an inherently more stable shoe or those with mild stability needs in the rearfoot

Andrea:
The Nike React Infinity Run Flyknit 3 is a great example of the stable neutral shoe category. The rigid heel clip, high medial longitudinal arch support, and rockered sole result in a centered ride. The medial and lateral sole flare in the rearfoot and forefoot contribute to the smooth ride. The narrower midfoot is less inherently stable, but I did not have any issues with this feature. The secure fitting Flyknit upper results in excellent lockdown and further stabilizes the foot without preventing motion. This shoe will be ideal for runners with neutral mechanics who prefer a rockered, centered ride.


THOUGHTS AS A DPT / FOOTWEAR SCIENCE

The Nike Study, a Breakdown
By Matt Klein

Despite Nike's study claiming the Infinity Run series prevents injuries, it actually suggests that runners tend to get injured more frequently in the Nike Structure. No shoe can prevent injuries, as running injuries are always multi-factorial (Thiesen et al., 2016). We may find that certain shoes may reduce the risk of injury for certain people, but no single shoe will do that for everyone.

Some of the early research on things that may decrease injury for runners involving shoes include shoe rotation, stability shoes for those with a history of pronation-related injuries and the use of shoes with softer midsoles in lighter runners. One of the larger predictors of injury in runners is a previous history of that injury, which has been a consistent risk factor in most activities even beyond running. Softer cushioning has been suggested to decrease injury risk only for lighter runners, while for those with larger body masses midsole hardness had no influence (Malisoux et al,. 2020). Those with a history of pronation-related injuries, including posterior tibial tendinitis/opathy, Achilles issues and more demonstrated a decrease in running injury (Malisoux et al., 2016). This is likely the one thing stability shoes may influence, but will only be specific to those injury types. The use of multiple shoes through a rotation has also been suggested to decrease injury risk (Malisoux et al., 2015). Exposure to different types of shoes throughout the training week may act as a type of cross-training, whereby the runner is exposed to different loads in different areas with different footwear, thereby decreasing the risk of one area being overloaded beyond capacity.

Outside of this, little high-quality evidence has been done on the relationship between footwear and injury risk. While companies may claim certain things, these marketing hypes have yet to show any validity. While it is helpful to have a good pair of comfortable running shoes, no one shoe will be perfect for an individual unless it has been designed specifically for them. We are not yet in an age of widespread, affordable, commercially available footwear customization. Thus, we suggest you look for a pair (or two if you can afford it) of shoes that is comfortable, is appropriate for the activity you are going to use them for most (easy running, faster running, road, trail, etc) matches your biomechanical needs and makes you excited to get out the door or onto the treadmill.

References

Malisoux, L., Chambon, N., Delattre, N., Gueguen, N., Urhausen, A., & Theisen, D. (2016). Injury risk in runners using standard or motion control shoes: a randomised controlled trial with participant and assessor blinding. 
British Journal of Sports Medicine50(8), 481-487.

Malisoux, L., Delattre, N., Urhausen, A., & Theisen, D. (2020). Shoe cushioning influences the running injury risk according to body mass: a randomized controlled trial involving 848 recreational runners. 
The American Journal of Sports Medicine48(2), 473-480.

Malisoux, L., Ramesh, J., Mann, R., Seil, R., Urhausen, A., & Theisen, D. (2015). Can parallel use of different running shoes decrease running‐related injury risk?. 
Scandinavian journal of medicine & science in sports25(1), 110-115.

Theisen, D., Malisoux, L., Gette, P., Nührenbörger, C., & Urhausen, A. (2016). Footwear and running-related injuries–Running on faith?. 
Sports Orthopaedics and Traumatology Sport-Orthopädie-Sport-Traumatologie32(2), 169-176.



RECOMMENDATIONS

Matt: I have enjoyed the Infinity Run 3 far more than expected. The ride is pleasant, especially for easy runs and long runs. The rocker is efficient, making miles go by easily. The upper is snug but adapts to your foot. The heel is stable, but not in an aggressive way. My major suggestions are to widen the midfoot and try to create a more anatomic shape in the forefoot. The narrow midfoot creates may instability for those with stability needs there. It is highly suggested that maximal shoes have wide lasts through their full length unless they are being used for faster runs (which means a faster transition and more forward momentum). Widening the sole at that point may increase weight, but this is meant to be an easy day shoe anyway. The upper is certainly sock-like given the snugger fit. I would encourage Nike to widen the toebox slightly to allow some space for the toes, but this may require additional security elsewhere. Outside of those things, this shoe has been pretty solid for its intended purpose.

Andrea: I was also surprised at how much I enjoyed testing the Infinity Run 3. My main recommendations relate to the fit of the shoe. First, I would recommend Nike make this shoe fit true to size. It is significantly shorter in length compared to the Streakfly or Alphafly, and slightly shorter than the Vaporfly Next%. I would also recommend making the laces a little longer for those with higher foot volume or who need to heel lock the shoe. A wider midfoot would contribute to greater stability and possibly an even smoother ride. Otherwise, I was very impressed with the fit and ride of the shoe and have greatly enjoyed using it for easy runs.

WHO THIS SHOE IS FOR 

Matt: The Nike React Infinity Run Flyknit 3 is for those wanting a softer rockered ride with a snug-fitting upper for easy runs and mileage. A snug-fitting upper will work for those wanting a closer fit or those with narrow feet. An inherently stable heel thanks to the heel clip and outsole flare will work for those who want some guidance without traditional stability methods. A softer ride (once the shoe breaks in) combined with a highly rockered sole will work for those who want an efficient ride over long miles. An extremely durable outsole tops this off, making the Nike React Infinity Run Flyknit 3 a good option for those who want a solid long-run/easy-run shoe.

Andrea:
The Nike Reach Infinity Run Flyknit 3 is an ideal easy day shoe for runners with neutral mechanics. The rockered sole, secure heel, and significant rearfoot and forefoot sole flare contribute to a smooth, protective ride that is ideal for tired feet and legs. The Flyknit upper provides a secure, sock-like fit that is very comfortable and without any pressure points. Runners who are typically between sizes may want to size up 1/2 size for adequate length.


GRADING 

Matt
Fit: B+/A- (Normal to snug fit with a secure heel. Toebox tapers, but flyknit upper does stretch somewhat)
Performance: 
B+/A- (A cushioned rockered ride for easy runs and long runs. No versatility into faster efforts)
Stability: B+ [Stable Neutral]  (Highly stable rearfoot, less stable midfoot. High level of guidance in rearfoot thanks to heel clip, sidewalls and outsole flare)
DPT/Footwear Science: B+/A- (Great inherent stability through the use of guidance methods in the rearfoot. Midfoot could be widened. Nike needs to still be careful regarding claims that this shoe prevents injuries, as it does not)
Personal: A- (A really solid shoe for easy and long runs. Upper does stretch to accommodate my feet, just wish I had a bit more room in the toes. It performs well at its intended purpose at easy-paced efforts)
Overall: B+/A-   

Andrea
Fit: B+ (Runs short, some runners may want to go up 1/2 size. Flyknit upper extremely comfortable and secure, shoe feels like it molds to your foot over time)
Performance: B+ (A great easy day shoe, but runner need to be patient with break in process. Rockered ride ideal for easy runs)
Stability: B+ (Nice example of stable neutral category except for narrower midfoot. Excellent rearfoot and upper security)
DPT/Footwear Science: B+ (A great stable neutral shoe, but shoes generally do not prevent injury)
Personal: B+ (The shoe took some time to break in, but was worth it once it did. Shoe runs short and kept me from testing on runs >1 hr)
Overall: B+ 


SHOP | SUPPORT DOR

Price: $159.95 at Running Warehouse

*Using the link to purchase helps support Doctors of Running. Thanks so much!

Check out Gear We Love
Ultraspire Fitted Race Belt: The best way to carry your phone and goods on the run. No bounce and various sizes for waist
Skratch Recovery, Coffee Flavor: Mental and physical boost post run. Coffee flavor is excellent and goes great straight into a fresh brewed cup
Feetures Socks: Massively grippy socks that will make you feel more one with the shoe
Huma Chia GelNatural and goes down easy. Powered Contributor Nathan Brown to his marathon
Trigger Point Foam Roller: Help get those knots out post-run and feel better for tomorrow
Theragun Massager: This small version is great on the go for working tired legs
Ciele Hat: Our team's favorite running hat of choice!

FURTHER READING

Inov-8 Parkclaw G 280 - A road to trail hybrid that ticks a lot of boxes for us
New Balance Fresh Foam X Tempo v2 - A freshly updated model that provides a low profile, versatile training option
Footwear Science: Should I Put Orthotics in My Running Shoes?
Puma Fast-R Nitro Elite - Puma's new super shoe packed with interesting technology
Saucony Xodus Ultra - A pwrrun pb fueled distance trainer for trails
On Cloudmonster
- On Running's new maxium cushioned shoe!
Reebok Nano X2
- The latest trainer out of the Nano series gets a great upper update

Find all Shoe Reviews at Doctors of Running here.

Thanks for reading!

FOLLOW DOCTORS OF RUNNING ON SOCIAL MEDIA

Facebook: Doctors of Running 
Youtube Channel: Doctors of Running 
Instagram: @doctorsofrunning 
LinkedIn: Doctors of Running
Strava: Doctors of Running
Podcast: Virtual Roundtable
Pinterest: Doctors of Running
***Disclaimer: These shoes were provided free of charge in exchange for a review.  We thank the people at Running Warehouse for sending us a pair.  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.

Please feel free to reach out, comment and ask questions!
Contact us at doctorsofrunning@gmail.com

NEXT: Footwear Science: Should I Put Orthotics in My Running Shoes?

Bottom Ad [Post Page]