Clinical Analysis of Running, Running Footwear, and Injury Prevention/Performance. The Doctor(s) of Running, using knowledge of human movement, clinical biomechanics and performance to bring you cutting edge reviews, science and knowledge.

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Asics Metaracer Review

Asics often waits to jump onto new trends until they ready to put their own spin on it. The Metaracer is just that. The lightweight, carbon fiber plated racer is Asics answer to the direction many racing shoes are going in the current market. As with tradition though, they have stuck to what they know best: creating lightweight fast racing shoes that tend to be a little closer to the ground. The Metaracer features plenty of cushioning for a light racing shoe, features a unique upper designed for performance and a bottom loaded plate. A great racing shoe, but very different from the other max cushioned distance racers worth talking about.

Specifications (per Running Warehouse)
Weight: 6.6 oz (men's size 9), 5.7 oz (women's size 8)
Stack Height: 30 mm / 21 mm
Drop: 9 mm
Classification: Mid Distance Carbon Fiber Plated Racing Flat

HIGHLIGHTS

Matt: The Asics Metaracer is a carbon fiber plated, lightweight racing flat featuring a snug fit and very breathable upper. The lightweight, lower density Flytefoam midsole provides plenty of cushioning, but the lower the ground ride makes this shoe best for the 5k to half marathon. A snugger fitting Japanese style take on the recent racing shoe design revolution, this one may be worth a look.

FIT

Matt: The Asics Metaracer fits true to size in my men's size 10. In typical Asics fashion, the fit is slightly long and narrow throughout. While running the shoe feels like it fits true as the upper fits comfortably. The forefoot and midfoot fit a bit snug, while the heel has a fairly average fit. There is an very small and flexible heel counter with a narrow strip up the back and two very low components circling the heel. It is small enough that I almost did not notice this shoe had one, so for those sensitive to this, the Metaracer is a great option. The weave around the heel collar is super comfortable against bare skin and while I would not suggest this for longer races, the upper does fit nicely against bare skin. This is one of the most breathable uppers I have experienced. Running in very hot weather (+100 degrees here in Southern California) has not been a problem and my feet have stayed cool. No that is not a USB port at the front, it is an additional vent for cooling. The upper is hydrophobic, meaning it repels water and sweat. There are very few if any reinforcements of the upper, so any direction other than running straight was a little concerning. Turning was not the most stable until I locked down the laces, which interact well with the upper. I did have to lace lock the shoe as the heel fit wider. Thus this shoe will easily stretch to accommodate narrow, medium and slightly wider feet. For wide feet though, it may be too snug and I have yet to find a 2E size on Asics Japan website.

RIDE

Matt: Featuring lower density Flytefoam, a fully rockered sole and a bottom loaded carbon fiber plate, the Metaracer has a unique ride for an Asics shoe. This is the smoothest heel I have ever experienced from Asics. Called "Guidesole", the heel is rockered very well and provides a smooth place to land. The toe spring starts very early and facilitates both the ankle and forefoot rocker. The sole is very stiff thanks to the bottom loaded plate, but the overall rocker is very smooth. The lower density Flytefoam provides plenty of cushioning, although the ride does feel a little closer to the ground. The heel is very bouncy and smooth, which transitions into a slightly firmer and quick rolling forefoot. There is a 9mm heel drop listed, although this feels far lower thanks to the early stage rocker and significant heel bevel, so those sensitive to drop should not be worried.

STABILITY

Matt: Although the "Guidesole" rocker and the plate provide some guidance, the Asics Metaracer is a neutral shoe with no true methods of stability. The narrow sole/last and lower density/softer Flytefoam create more instability than anything and I could feel my midfoot hanging over the medial side of the shoe. The heel and midfoot are not the most stable due to those above factors. The forefoot is far better given the significant rocker, slightly firmer ride and slightly wider shape compared to the heel and midfoot. However, this is not a shoe for those who need even mild stability. For those with more narrow feet that fit the last, the platform may fit better and thus may be a bit more stable.

SPEED

Matt: The Asics Metaracer is a fast shoe. The light weight, snug fit and closer to the ground ride makes this shoe best for workouts like fast intervals and tempo runs at the longest. The low density Flytefoam has some decent bounce that combined with the low plate and lower ride (compared to other recent distance racing shoes) makes it excel during faster and shorter distances. Race wise the Asics Metaracer will be best for most people from 5k to half marathon. Only the elite or experienced will be able to take this shoe up to the marathon given the lower to the ground ride. For me, the Metaracer is limited at longer distances due not being the most stable, but the speed is definitely there for shorter distances.

DURABILITY

Matt: After >20 miles of both hard and easy runs, I am only seeing some light wear only on the exposed Flytefoam in the heel. The outsole material is very durable and should be handle a higher number of miles than most 5k-10k type racing flats. The Flytefoam has not changed in terms of responsiveness, although there are some theoretical concerns that the lower density may compress early. The upper has no signs of wear outside of a little dirt. I expect a very high number of miles out of the Metaracer on roads. The outsole has a great amount of traction on road (although make sure to lock down the upper). However, the smooth outsole limits this shoe to road only running/racing.

THOUGHTS AS A DPT 

     The full length rockered sole is very different for an Asics shoe, let alone a racing flat from them. While a few have begun to surface recently, this is the most pronounced example. The heel bevel feels so much smoother than the traditional Asics ride, while the toe spring starts early and is less aggressive than some of the earlier shoes like the Metaride, Glideride and others. The toespring in the Metaracer starts a little farther back compared to others, which means it may facilitate not just the forefoot rocker (toes) but also the ankle rocker (talocrural/ankle joint). For those with very stiff ankles, this component combined with the higher drop (although it still feels lower than 9mm to me) may be a great racing option for those with stiff ankles looking for a lightweight racing shoe. 


     The design of the upper is particularly airy. Several comments have been made that the goal of the design is to keep the temperature of the feet cool to improve efficiency. It is certainly true that as temperatures rise, running performances tend to suffer (El Helou et al., 2012). It is also well known that heat training can be just as difficult as altitude training, although the exact mechanisms are different (Saunders et al., 2019). The body certainly has to work harder in the heat as it performs best at certain temperatures, pH levels, etc (Homeostasis). What is not clear in the research is if keeping your feet cool during the heat or in normal temperatures can actually maintain or improve performances. This makes sense theoretically with high temperatures, but negates the fact that the feet only make up a small portion of the body's surface area and mass (this is the exact same issue we had with the barefoot/footstrike debate). In regards to internal body temperature and efficiency, some of the evidence suggests that runners may slow down toward the end of marathons regardless of internal body temperature (Lee et al., 2010). So while internal temperature and cooling may be important variables, how important they are compared to other factors like fueling, pacing, footwear mechanics, etc are unknown. Even more unknown is whether having an upper that supposedly keeps the foot cooler provides an advantage in anything but hot temperatures. In normal or cold temperatures there may be no (or a negative effect). So while I think this is interesting, I caution those thinking that cooling the feet will provide a distinct advantage, particularly in normal and stable weather conditions.

RECOMMENDATIONS 

Matt: My major recommendations for this shoe are to improve the stability and to reconsider the midsole material and stack height for the general consumer. The Asics Metaracer is a great shoe, but for anyone except those with narrow, stable feet, this instability may cause some issues over longer miles. Hence the limitation to shorter distance races. If Asics wants to reach a larger consumer base, they need to improve the stability of the sole and potentially think about widening that base (particularly in the midfoot and heel). The other component is that higher stack is in right now. I personally like low to the ground racing flats and am happy to see one after it seems like most companies are moving away from them. However, if the Metaracer is to compete with other brands and appeal to consumers that seem to prefer more cushioning, they may want to think about increasing the stack height AND using a lighter and more resilient foam than Flytefoam (even if it is lower density). Otherwise this is a great shoe.


WHO THIS SHOE IS FOR (Conclusion)

Matt: For those looking for a 5k to half marathon, low to the ground racer with a snug and airy fit, the Asics Metaracer is a great choice. Featuring a full length rocker and an early toespring that should work well for those with mobility issues at the toes and ankles, the Metaracer has a fairly smooth ride. Although not the most stable shoe and limited at longer distances, those using it for shorter distances and intervals should be fine. A rare low to the ground, carbon fiber plated shoe, the Asics Metaracer is an interesting combination of old and new racing flat design.

GRADING   

Matt

Fit                    9 /10 (Snug fit, super breathable)
Ride                 9.5 /10 (Smoothest Asics heel ever, good roll and bounce)
Stability           7 /10 (Narrow sole not the most stable. Offset slightly by rocker)
Speed               9.5 /10 (Great for 5k-half marathon, limited at longer distances)
Durability        9.5 /10 (Very minimal wear at >20 miles)

Total Score: 89 % (M: 8.9 /10 )


Thanks for reading!

TESTER PROFILES:   

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 70-100 miles per week and trains at a variety of paces from 8min 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.  He is particular to less cushioned shoes and close to the ground shoes, but can handle a little cushion when he gets beat up.

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.

Matthew Klein, PT DPT OCS FAAOMPT
Doctor of Physical Therapy
Board Certified Orthopedic Clinical Specialist
Fellow of the American Academy of Orthopedic Manual Physical Therapists

Nathan Brown PT DPT MS
Doctor of Physical Therapy 
Masters in Anatomy and Clinical Health Science
Movement Performance Institute Certified in Advanced Functional Biomechanics 

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

***Disclaimer: These shoes were purchased with a medical discount (40%).  This in no way affected the honesty of this review. We put at least 35-50 miles on trainers and 10-25 miles on racing flats prior to reviewing them. Currently I have 22 miles (Matt) on my pair. Our 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. El Helou, N., Tafflet, M., Berthelot, G., Tolaini, J., Marc, A., Guillaume, M., ... & Toussaint, J. F. (2012). Impact of environmental parameters on marathon running performance. PloS One, 7(5), e37407.

2. Lee, J. K., Nio, A. Q., Lim, C. L., Teo, E. Y., & Byrne, C. (2010). Thermoregulation, pacing and fluid balance during mass participation distance running in a warm and humid environment. European Journal of Applied Physiology, 109(5), 887-898.

3. Saunders, P. U., Garvican-Lewis, L. A., Chapman, R. F., & PĂ©riard, J. D. (2019). Special Environments: Altitude and heat. International Journal of Sport Nutrition and Exercise Metabolism, 29(2), 210-219.

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