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

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Puma Fast-R Nitro Elite 2: Wild Territory
By Matthew Klein

The first Puma Fast-R was (is) an incredibly unique racing shoe. Its geometry was completely different than standard shoe design with two completely separate and different midsoles locked together by a visible carbon plate. A slab of bio-based Nitro Elite foam sat in the front, providing a fast bouncy ride while an EVA heel created a firmer, quick and somewhat abrupt transition in the back. Although designed as a long-distance racing shoe, the DOR team found that it worked better as a shorter-distance racer as it seemed to work better for faster and shorter efforts that got you more onto your toes. This was the opposite to the Deviate Nitro Elite, which still could move quickly but had versatility across a variety of footstrikes and distances. The similarity in shorter distance use between the Fast-R and the Fast-FWD may have motivated Puma to move the Fast-R 2 in a different direction. It now returns as a completely different shoe despite sharing some similar visuals to the original. A taller stack height, softer and homogenous cushioning in both the rear and forefoot, lower volume but wider upper and an extended and an extended plate make for another unique addition to the super distance racing shoe category.

Puma Fast-R Nitro Elite 2
Price: $260.00 at Running Warehouse (February)
Weight: 8.5 oz, 240 g (men's size 9), 7.4 oz, 212 g (women's size 8)
Stack Height: 40 mm / 32 mm
Drop: 8mm
Classification: Super Distance Racing Shoe




RUNNING SHOE SUMMARY

The Puma Fast-R Nitro Elite 2 is a longer-distance super racing shoe for those who want a lower-volume upper, a maximal stack height superfoam midsole and an extra long plate for those who have the calf/ankle strength to push themselves forward. The new ULTRAWEAVE upper provides a secure, lower-volume fit that hugs and secures the foot. The new NITROFOAM Elite midsole provides a large amount of bounce regardless of whether you land in the heel or forefoot. The extended plate and foam combination make this shoe best for faster efforts while the extra weight pushes it toward being a better option for half marathon to full marathon distances. A specialized tool for specific runners who utilize their ankle/calves over moderate to longer distance races, the Fast-R Nitro Elite 2 continues to demonstrate Puma's commitment to trying different concepts to optimize performance.  

SIMILAR SHOES: Nike Alphafly 2
PAST MODEL:
Fast-R Nitro Elite

FIT


The Puma Fast-R Nitro Elite 2 fits me extremely true to size in my normal US men's size 10. The ULTRAWEAVE upper provides an extremely low volume and close fit throughout the length of the shoe. The material is thin yet strong, providing a somewhat compressive fit along the entire foot. The forefoot fits normal to slightly wide but this is offset by the upper being so low across the toes. The midfoot fits similar with a snug fit. The tongue is thin integrated with the upper. Fortunately the fit was snug enough that I did not have to tie down the laces as the tongue does not protect the top of your foot that much. I also did not have to lace lock the shoe as the snug fit did a fine job keeping my foot locked onto the platform. The heel fits snug with the same thin ULTRAWEAVE and mild additional padding around the heel counter. The Achilles tab comes up extra high and abraded some of the skin off the midportion of my Achilles area. This was my mistake for wearing no-show socks, so I would highly recommend wearing at least crew socks with this shoe to avoid chaffing in that area.

In place of a heel counter, there is a stiff plastic fin that sits on the posterior-most aspect of the upper. This did a great job of giving some structure to the rearfoot but did bug my calcaneus/heel bone. It wasn't terrible, but my Haglund deformity is calm right now. Those sensitive to stiff counters or compressive will notice this on the back of their heel. The close fit of the upper made these excellent while wearing but challenging to get on and off. The heel pull tab was somewhat helpful here but be aware getting your feet and out of these can be a challenge - a decent trade-off for an extremely secure and light fit.




PERFORMANCE

The Puma Fast-R 2 Nitro Elite is a super racing shoe for those who can produce a high level of force at their ankles. The midsole is now comprised of two separate sections of NITROFOAM ELITE, which is apparently some new blend of super foam. Having both the heel and forefoot the same material makes for a consistent transition at between the two. The gap is not super noticeable at first but can become apparent with fatigue or slower paces.

At faster paces, which is what this shoe is solely meant for, the midfoot transition occurs fast enough that it isn't that big of a deal. The heel is beveled and is soft, providing a compliant and resilient feel. This quickly bounces you forward into the forefoot, which with the extended plate provides a longer forefoot transition. This makes the shoe feel a little bit more stiff than normal, but fortunately there is a large forefoot rocker that offsets most of this. With the thick plate, there is obviously no flexibility at the forefoot, but the rocker makes transitions fairly easy off the toes. Landing up front also provides a resilient feel, although the additional outsole material and slightly less midsole height makes for a relatively firmer ride compared to the heel. It is still extremely responsive and bouncy. However, the extended forefoot plate does make it feel slightly weird to forefoot strike.

Again, at slower paces the midfoot and forefoot transition is just a little awkward. When the paces gets really fast though it becomes easy to really push hard at toe off. I have used this shoe for two fartleks, an easy run and a tempo run at marathon pace. The faster fartleks felt the best as it was easy to push off hard while running fast. The easy run felt awkward and it was quickly apparent this shoe was not designed for slower paces. The tempo run felt decent and it was easy to get into a rhythm. I did begin to notice calf fatigue as I progressed into the later stages of the tempo (~35 min at a 6 min per mile pace). Additionally, the higher weight was apparent. As I have continued to get miles on these, I feel they work best as a super training shoe for faster miles. Short to moderate-length workouts have been best for me in these, while I would elect to take something with a more efficient forefoot for longer distances (like the deviate nitro elite 2/3). Those who can push off through their ankles/calves for longer distances will be able to use this more efficiently over a marathon than I. It is just a specific tool for a specific person. The higher weight makes me want to say this is a longer-distance racer but the way the forefoot is designed and responds challenges that.

Despite the conundrum I have with paces/purpose, the outsole traction and durability have been consistently fantastic. I ran on wet/icy roads in Oregon for most of my miles in these and found the Puma Grip outsole to grab the road extremely well. The exposed plate and forefoot gap in the outsole keep this shoe for road only. I have tried brief trail but had rocks get stuck in that groove immediately. Durability-wise, I have 30 miles on my pair and there is no wear on the outsole. I will take these to 100 miles like the originals and do expect them to last even longer. 



STABILITY

The Puma Fast-R 2 is a neutral racing shoe. There are no traditional elements of stability. There are a few methods of guidance, mostly via the sole being far wider than previous. The forefoot is especially wide with significant medial and lateral sole flare. Additionally, the middle groove reduces weight while creating a central guidance line. Additionally, the additional extension of the plate anteriomedially provides some lateral guidance at toe-off, which may be beneficial for those that collapse medially at the forefoot/across the 1st toe. The midfoot is fairly neutral with no sidewalls. Any guidance at the midfoot comes as a result of the heel and forefoot, so those with midfoot stability needs and running at slower paces may find this area highly neutral. The heel is now slightly split with a central groove through it. This allows for the lateral and medial columns to collapse separately. For those that hit the lateral column, this may act like a crash pad that keeps you slightly lateral upon contact. The heel bevel is centered, so there is no real bias there.

As someone with guidance/stability needs, I found the forefoot to be the most stable part of the shoe. When I was running fast paces, transitioning quickly through the shoe and staying farther forward on the shoe, I found it to provide plenty of guidance for someone like m with mild guidance needs. With longer and slower miles, I found the midfoot and to a degree the heel to be far more neutral. So those with mild forefoot stability needs and neutral needs in the heel and midfoot will do best with the Fast-R 2.




Thoughts as a DPT: Longer Plates and Longer Lever Arms
By Matthew Klein

We have talked extensively on the relationship between plates, stiffness and how different levels of stiffness will work for different people (Agresta et al., 2022). We also know that those levels of stiffness will work differently at different speeds (Mcleod et al., 2020). The plates being extended into the forefoot act as levers, increasing the longitudinal bending stiffness and allowing some runners to potentially transfer force differently during the midstance to terminal stance phase of gait. Shoes with increased longitudinal bending stiffness tend to cause runners to shift their "point of force application" or where they push off forward (Willwacher et al., 2014). This essentially means the pivot point moves forward to compensate for the stiffness and increased lever arm created by the plate. Further increasing the length of the plate not only increases stiffness but also moves that pivot point even farther forward. 

Going back to basic physics, levers have an optimal length for the amount of torque that must be used to move them. A longer or shorter lever is not necessarily better and from a footwear standpoint must match the mechanics of the runner. There is solid evidence that increased stiffness of midsoles through plates (and no changes in other factors) change biomechanics but not economy (Beck et al., 2020; Healey et al., 2022). Shoes with stiffer midsoles require more force to be produced at the toes and ankles and thus shift work from the hip and knee to the ankles (Cigoja et al., 2019). This has NOT been shown to improve efficiency, which is extremely important over distance races (Beck et al., 2020; Healey et al., 2022). It just means that it will make you work harder at your ankle/calves, which may be optimal for some people and not for others.

The key behind all of this is that the evidence has repeatedly suggested that a stiffer or longer plate is NOT going to improve running efficiency or economy in human beings. It may change what joints/muscles are most engaged or required for forward propulsion, but they will not improve your running efficiency by a large degree. The plate by itself does NOT act alone, the foams have repeatedly been shown to have a greater impact on running efficiency and the biggest factor in how efficient a shoe is relates to how all the factors (midsole foam, plate, geometry, weight, etc) interact. So if you want a shoe that is going to allow you to push off more through your ankle and work your calves a bit more, the Puma Fast-R Nitro Elite may be a great option. If you want to improve your running economy/efficiency, an extended plate is not the way to do it. 

References:

Agresta, C., Giacomazzi, C., Harrast, M., & Zendler, J. (2022). Running injury paradigms and their influence on footwear design features and runner assessment methods: a focused review to advance evidence-based practice for running medicine clinicians. Frontiers in Sports and Active Living4, 74.

Beck, O. N., Golyski, P. R., & Sawicki, G. S. (2020). Adding carbon fiber to shoe soles may not improve running economy: a muscle-level explanation. Scientific Reports10(1), 17154.

Cigoja, S., Firminger, C. R., Asmussen, M. J., Fletcher, J. R., Edwards, W. B., & Nigg, B. M. (2019). Does increased midsole bending stiffness of sport shoes redistribute lower limb joint work during running?. Journal of Science and Medicine in Sport22(11), 1272-1277.

Healey, L. A., & Hoogkamer, W. (2022). Longitudinal bending stiffness does not affect running economy in Nike Vaporfly shoes. Journal of sport and health science11(3), 285-292.

McLeod, A. R., Bruening, D., Johnson, A. W., Ward, J., & Hunter, I. (2020). Improving running economy through altered shoe bending stiffness across speeds. Footwear Science12(2), 79-89.

Willwacher, S., König, M., Braunstein, B., Goldmann, J. P., & Brüggemann, G. P. (2014). The gearing function of running shoe longitudinal bending stiffness. Gait & Posture40(3), 386-390.



RECOMMENDATIONS

The Puma Fast-R 2 takes some big steps forward and a few back. The use of a super foam in the rearfoot makes this shoe more useable for those who land at the heel. It also makes the ride far more consistent, rather than the abrupt and often awkward transition the Fast-R 1 had. The additional stack height and new foam make the shoe far more bouncy than previous and actually brings it up to the legal stack height limit. This maximizes the stack height and performance benefit from the super foam. The similar midsole materials in the heel and forefoot make the transition far smoother than the prior version's clunky heel. The forefoot design is great with the wider shape and central groove, which provides a stable place to push off from. 

The challenges with the Fast-R 2 is that the extended plate is a bit gimmicky (see thoughts as a DPT above) and the weight increase is disappointing. The extended plate will likely make you work harder at the ankle/calf, which is great for shorter efforts up to the half marathon but not for longer distance races like the marathon. The exception may be those who use a strong ankle strategy for propulsion during their running gait. So like the previous version, this shoe still feels better at shorter faster efforts. However, the weight increase of one oz / 30 grams holds it back from that, keeping the Fast-R 2 in a weird place. I would encourage Puma to continue to experiment, which they are clearly doing quite a bit of, in the areas of midsole shaping. The midsole material is absolutely awesome and I am excited to try the Deviate Nitro Elite 3. However, to be competitive in this area, sub 8 oz is important. Thus, I would suggest removing the extended forefoot plate (unnecessary weight) and consider making the split in the forefoot longer and slightly wider. I would also suggest removing the shark fin from the upper as it puts a ton of pressure on the calcaneus and I think appropriately placed PWRTAPE could do a better job of providing structure to the rearfoot. This combination of factors could get this shoe down to 8 oz and make the forefoot transition far smoother/more efficient. I again applaud Puma for trying things, but the extended forefoot plate is NOT something I would keep. Finally, the heel tab also needs to be fixed as it has repeatedly taken skin of my Achilles, which is not optimal for a shoe meant to be worn for longer periods.

WHO THIS SHOE IS FOR

The Puma Fast-R Nitro Elite 2 is for those who want a highly cushioned, forward-rolling/bouncing super shoe that responds better the more you push through your ankles. The upper is extremely low volume and holds the foot well despite being so light. The heel tab can rip skin off, so those interested should always wear long socks. The ride is far smoother than previous with a consistent transition from the heel to the forefoot. Those who really drive through the ankle will like these as they feel best running at faster paces. The increased foam underfoot is apparent, so those who wanted more cushioning in Version 1 will enjoy the extra stack height here. Those who do not mind a little extra weight will not be bothered by the one oz increase in weight in the Fast-R 2 Nitro Elite. 

In my mind, this is an extremely expensive training companion to the Deviate Elite series. Getting more expensive while dramatically increasing weight does not make sense to me, particularly when adding mechanisms that are known to NOT improve running efficiency. Despite the awesome new foam, I would encourage Puma to drop the price on these. They do not compete with the Nike Alphafly or Saucony Endorphin Elite and are an even more niche product given the extended plate will only work for a small group of runners. The new foam, upper design and stack height have made me really excited to try the Deviate Nitro Elite 3, but the Puma Fast-R series needs more work.


GRADING

Matt
Fit: B+/A- (Snug, low volume, secure fit. Achilles tab can cause chaffing so use long socks)
Performance: 
B+/A- (A fast shoe that works well if you can pivot off the extended forefoot. Heavier than previous and in a weird place where it works for shorter/moderate workouts but there are lighter options for racing)
Stability: B/B+ [Neutral] (Stable forefoot from width and plate, neutral midfoot and heel)
DPT/Footwear Science: B- (The full-length NITROFOAM Elite improves the transition but the extended plate uses an idea that has been proven not to work in a weigh that unnecessarily increases the weight)
Personal: C+/B- (An expensive option for workouts but not something I would race in. Heel tab has also repeatedly ripped up the skin over my achilles. Not something I would buy given the cost and use conundrum)
Overall: 


SHOP | SUPPORT DOR

Puma Fast-R Nitro Elite 2
Price: $260 at Running Warehouse (February)

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

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FURTHER READING

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TESTER PROFILES:

Matthew Klein, PT DPT PhD(c) OCS GCS FAAOMPT
Doctor of Physical Therapy
Assistant Professor of Physical Therapy - West Coast University
Board-Certified Clinical Specialist in Orthopedic & Geriatric Physical Therapy
Fellow of the American Academy of Orthopedic Manual Physical Therapists

Dr. Matthew Klein is a 150 lb male with notable PRs of 14:45 for 5k and 2:32:44 for the full marathon.  He typically runs 50-70 miles per week and trains at a variety of paces from 8:30 min per mile recovery runs to 4:40 per mile 1k repeats.  He prefers firmer and responsive shoes with snug heels and medium to wide toe boxes.  The stability guy of the group, he also prefers a little guidance in his footwear. However, as a researcher, clinician, and running shoe aficionado, he will run in anything.

David Salas PT DPT CSCS
Doctor of Physical Therapy
Certified Strength and Conditioning Specialist

Dr. David Salas is a 135 lb male with notable PRs ranging from 3:54 in the 1500m to 2:25:07 for the marathon. He typically runs 70 to 80 miles per week and trains from about 7:30 recovery runs to fast shorter efforts at 4:30 pace. He normally prefers neutral shoes with a firmer ride, but is completely open to other types of shoes.  He is a footwear enthusiast at heart and will always appreciate a high-quality shoe when it comes around. 

Nathan Brown PT DPT OCS
Doctor of Physical Therapy 
Board Certified Orthopedic Clinical Specialist
Movement Performance Institute Certified in Advanced Functional Biomechanics 

Dr. Brown is a 155 lb male with notable PRs of 18:18 5K, 39:25 10K, 1:29:01 half marathon, and 3:29:44 marathon. He typically runs between 20-50 miles per week at a variety of paces from 8:00-9:00 min/mile for recovery runs to 6:45-7:15 min/mile for tempo runs. He typically prefers shoes that provide some cushioning underfoot but still maintain a mildly firm yet cushioned feel. 

Bach Pham MS
Marketing and Social Media Manager
Master of Arts in Cultural Anthropology

Bach Pham is a 140 lb male with PRs of 23 5K, 52 10K. He typically runs between 25-35 miles per week at a variety of paces between 8:30 (tempo) -10:00 (recovery) min/miles. He typically prefers shoes that provide some mild to firm cushioning underfoot that is lightweight and responsive. Currently, his goals are to complete the half and marathon distances.

Andrea Myers PT DPT OCS
Doctor of Physical Therapy
Board Certified Orthopedic Clinical Specialist
Certified Bike Fitter

Dr. Myers is a 130lb female with notable PRs of 18:41 5k, 38:02 10k, 1:24:34 half marathon and 3:04:48 marathon. She typically runs 50-70 miles per week at paces ranging from 8:00-9:00 min/mi for recovery runs, 6:30-6:45 min/mi for tempo runs, and 5:20 min/mi for mile pace intervals. As a lateral midfoot striker, Andrea prefers lower drop (<8mm) shoes that are on the firmer side and have ample room in the forefoot.

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 Puma 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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