While other guest contributors here have had some recent success with New Balance, my history is mixed. My introduction was the New Balance 904, a lightweight stability shoe that was right up my ally back in 2010. From then on however, I had issues with fit, durability and responsiveness. Things have definitely changed with 890v6 (REVIEW) and New Balance has shown a clear shift toward the performance end of the spectrum in terms of fit, feel and responsiveness. The Fuel Cell is nitrogen infused foam that New Balance has used in a limited number of shoes, but none of them lightweight until now. The Impulse fills the gap as a faster workout/race shoe utilizing this compound and it certainly lives up to those expectations.
Weight: 8.2 oz (mens size 9)
Stack Height: 23mm / 17 mm (heel/forefoot)
Drop: 6mm
Classification: Lightweight Trainer/Racer/Workout Shoe
FIT
New Balance uses a bootie construction that is extremely comfortable against the skin. It is snug and holds the foot well, yet has a more anatomical and straight lasted forefoot. The heel and midfoot fit much closer and narrower to the foot. Thanks to the close upper, no heel counter is present in this shoe. So this will be a dream for those with Haglund Deformities looking for a faster shoe. The upper creates almost a custom fit because of the uniform hold on the foot. However the only issue is that it fits so snugly, it is hard to get on. The hold around the heel is particularly good, which is necessary due to the lack of any counter. However that hold means that getting the shoes on can be a workout itself. If you think of this upper similar to compression socks, you'll get a good idea of how it feels. Not quite as compressive, but similar in terms of donning/doffing the shoe. Other than that, this upper truly disappears on the foot. The mesh is extremely comfortable and I have used these shoes sockless almost every run without any blisters or hot spots. Socks will work fine, but at least walk around without socks to get a feel of what more companies should be doing comfort wise.
RIDE
The nitrogen infused fuel cell in the forefoot works very well to provide a high amount of rebound during faster running. That combined with great flexibility of the forefoot not only makes for a fast ride, but a smooth one during toe off. I found myself picking up the pace even on easy runs and found that this shoe works better for uptempo runs, workouts and higher speed paces. The full ground contact sole provides a great stable base on the ground, especially with the wider forefoot. Toe off is very stable, but the EVA in the rearfoot is a little more jarring and not as fun to land on. So for forefoot strikers, the ride will be very smooth. For heel strikers, the ride will be more firm until you get to toe-off. There is a little bit of heel bevel, but the forefoot flexibility and fuel cell material lend to a far smoother ride up front.
The lower drop is evident and despite the listing of 6mm, I might put it a little lower at 3-4mm (not that 1-2mm is a deal breaker). The fuel cell in the forefoot definitely lends to getting up on your toes, which is another reason I delegated this shoe mostly to track and speed days.
STABILITY
The wider forefoot adds quite a bit to the stability up front. For those that land up there, the increased surface area will lend to a stable ride. Like most shoes, the midfoot is a bit narrower, so expect average stability up there. There is a bit of an arch there, so expect a little hug there into the foot that will come more from the upper than the midsole. The heel, like the forefoot, has a little wider base, which is rare for a workout or race shoe. Thanks to that and the firmer EVA, the heel also provides a decently stable (but firm) ride. This is not a shoe I would look for though if you have high stability needs, but may be better than a very narrow lasted shoe (like the 1400 for example with its overall narrow last and narrow midfoot) for those that need a bit more shoe during faster running.
SPEED
The Fuel Cell Impulse is meant to go fast. It isn't the lightest shoe out there, but provides plenty of speed and protection, particularly in the forefoot. This may be a great shoe for those who have a history of metatarsal stress fractures or reactions to use in place of lighter racing flats or spikes on track days for a majority of workouts. I found the Impulse to work best for track workouts, intervals, tempos or fartlek workouts. It worked especially well when my legs did not feel fresh enough to put on track spikes or lighter weight flats. The forefoot flexibility and fuel cell kept the front of my foot happy and definitely saved my calves even when hammering fast repeats. So the shoe can move very fast and definitely is meant for workouts, it just has a bit more there to protective you.
It does not do as well for slower or recovery days due to the geometry of the shoe lending to getting up more on your toes for speed. For forefoot strikers who like lighter weight trainers or close to the ground shoes, this will probably work for you as a daily trainer if you have run in shoes with similar specs in terms of weight and drop. It is definitively a fast lightweight trainer/workout shoe that would actually work for a variety of race distances if you find many racing flats to not have enough cushion there for you. I could see many using this as a 5k shoe and others even taking this up to the marathon (although I would put the half marathon as a limit personally).
DURABILITY
Most workout shoes, racers and track spikes do not have good durability. Durability is generally sacrificed for the lighter weight. That is definitely not the case in the Fuel Cell Impulse. This is a very durable shoe. The blown rubber placed in the forefoot and lateral heel have resisted wear fairly well. Over the course of 32 exclusively fast miles on the track and road, the sole has held up very well. I see the Fuel Cell far outlasting the EVA, but the ride lasting far longer than a track spike or true racing flat. The upper has had no issues despite the close and thin fit. So this would be a far better investment for most workout days for the money. Then save those track spikes or flats for key workouts or races.
THOUGHTS AS A DPT
Stress fractures are very common in the running population, accounting for up to 50% of injuries (Milner et al., 2006). These are particularly common in the collegiate population, which may be due to the fact that more time is spent in spikes and racing flats than the general population in addition to far higher mileage and intensity. Metatarsal and tibial stress fractures are two common ones I see in and out of clinic. From my anecdotal experience, the metatarsal stress fractures seem to occur more often in forefoot strikers and the tibial stress fractures occur more often in heel strikers. This is NOT always the case, but something I have seen frequently.
Image from Podiatry Placentia
Stress fractures are believed to occur due to chronic overloading of the bone without adequate time for the tissue to heal. Thus microfractures occur which worsen to the point that an inflammatory response occurs, then pain usually starts. Many athletes may have stress fractures and no symptoms, which is another thing I have seen (weird story of seeing a cross country runner with a stress fracture of her 2nd metatarsal on x-ray but had no pain there. Her pain was in her upper achilles!). These injuries all come down to more load than the body can handle. In this case, it is the passive structures that take too much load and can't heal fast enough. Those I have seen that are at particular risk are forefoot strikers, those who over utilize their calves (gastrocsoleus complex connects via fascial layers into the metatarsals, which help transfer the force generation from those muscles into the ground during toe-off), those with poor proximal loading and stability (hip strength, poor core/pelvic stabilization, etc) and those that over train. Anything that causes excessive load into a structure can put it at risk for a bony injury.
Image from WebMD
So for runners looking to hit the road or track hard, having a lightweight trainer like the New Balance Fuel Cell Impulse may be a great way to save the legs or calves. The fast ride contributes to speed while the additional cushioning keeps the legs far fresher than putting on spikes or flats. While it is very important to get the body used to wearing competition shoes (especially with longer distance racing), different people will be able to handle different amounts of load. Some people are more durable and can handle high training volumes in very minimal shoes, while others cannot. Those than cannot handle those higher loads should not be afraid of lighter shoes for faster workouts. They may just need an "in between" shoe to do most of their workouts in. The Fuel Cell Impulse is a great example of a midweight trainer/racer that will work very well for this. The lower drop is similar to may track spikes and flats, while the snug mesh still gives that fast second skin feel.
CONCLUSION
The New Balance Fuel Cell Impulse is a lightweight trainer/racer meant to go fast but save your legs. The fuel cell in the forefoot provides some great bounce at high speeds and the snug mesh upper does a great job of holding the foot on the platform without a heel counter or overlays. Meanwhile, the forefoot flexibility and additional cushioning means you can save your legs while still hammering workouts. This shoe is best utilized for fast running, workouts, or races for those looking for a more cushioned racing flat or workout shoe. I would not use this shoe for daily training or easy runs unless you are used to training in lower to the ground lightweight trainers or racers. I applaud New Balance for creating a great fast shoe that is worth of the Fuel Cell. Now I am curious to see this material implemented into a true racing flat!
Thanks for reading!
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 area, I am currently taking clients for running evaluations.
Dr. Matthew Klein, PT DPT OCS
Doctor of Physical Therapy
Board Certified Orthopedic Clinical Specialist
Kaiser SoCal Manual Therapy and Sport Fellow
Doctor of Physical Therapy
Board Certified Orthopedic Clinical Specialist
Kaiser SoCal Manual Therapy and Sport Fellow
***Disclaimer: These shoes were provided free of charge in exchange for a review. We thank the people at New Balance for sending us a pair. This in no way affected the honesty of this review. We put at least 50-75 miles on trainers and 15-30 miles on racing flats or workout shoes prior to reviewing them. Currently I have 32 miles on my pair. My views are based on my 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.
References
1. Milner, C., Ferber, R., Pollard, C., Hamill, J., Davis, I. (2006). Biomechanical Factors Associated with Tibial Stress Fractures in Female Runners. Medicine and Science in Sports and Exercise. 38(2); 323-328. DOI: 10.1249/01.mss.0000183477
2. Nagel, A., Fernholz, F., Kibele, C., Rosenbaum D. (2008). Long Distance Running Increases Plantar Pressures Beneath the Metatarsal Heads. Gait and Posture. 27(1): 152-155. DOI: 10.1016/j.gaitpost.2006.12.012
References
1. Milner, C., Ferber, R., Pollard, C., Hamill, J., Davis, I. (2006). Biomechanical Factors Associated with Tibial Stress Fractures in Female Runners. Medicine and Science in Sports and Exercise. 38(2); 323-328. DOI: 10.1249/01.mss.0000183477
2. Nagel, A., Fernholz, F., Kibele, C., Rosenbaum D. (2008). Long Distance Running Increases Plantar Pressures Beneath the Metatarsal Heads. Gait and Posture. 27(1): 152-155. DOI: 10.1016/j.gaitpost.2006.12.012
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