Asics Tartherzeal 6 Review

Japan does things differently.  While the American market continues to focus on cushioning, Japan continues to remain traditional with their history of interesting, firm, lightweight racing shoes.  The Tartherzeal has been a shoe I experienced once as I went through a frenzy trying the pre-Boost Adidas Takumi Series, Nike LunarSpider and Nike Zoom Speed series.  Like most of the others (and thanks to Japanese Tradition) the Tartherzeal has remained a high drop, lightweight fast ride.  I figured it was time to grab a pair and write a review and was pleasantly surprised that the tradition of this shoe has been maintained. 

Trying to get good photos with an all black shoe at night is difficult.  
There are more and brighter colorways I promise. 

Specifications (per Asics America)
Weight: 5.6 oz
Stack Height: 20mm / 10mm (Heel/Forefoot)
Drop: 10mm
Classification: Racing Flat

Fits a half to quarter size short.  Width is ok.

FIT/UPPER

The upper is a classic mesh and is light and slightly airy.  The fit of this shoe is about a half to quarter size small, so I suggest going a half size up, especially if you are between sizes.  That is not because it is narrow, but because it fits short.  For that like a short fit for their racing shoes, stick with your normal size. Even with my size 10 that was too small, there was plenty of width in the shoe.   So the fit is fairly average width wise for a racing flat and should give enough room toe box wise for most people.   This is thanks to the adaptive mesh, which seems to do as it is named.  The heel fit is snug and although I lace locked the shoe, the heel is held in fairly well by default.   The heel counter is lighter and more flexible as this is a racing flat, so I have luckily not had any heel issues thus far.  The midfoot is medium to narrow width like most racing flats and the partially elastic laces do a great job of creating an appropriately snug fit when tied down.  


There is a wide version of the Tartherzeal 6 available over in the Asian market.  I have tried this one and found that as with previous models, the additional width is almost exclusive to the forefoot.  I highly suggest looking at the wide version for those wanting more room in the forefoot.  Color wise the only color available through traditional methods is the all black you see in the photos.  There are a few other exciting colors available through Rakuten and Ebay.  


RIDE/MIDSOLE

Previous Asics racing flats I found to be a little harsh, which is odd coming from someone who loves firm rides.  The new FlyteFoam midsole is much bouncier and less harsh than previous, yet retains the fast feel associated with a firmer midsole.  Flytefoam really isn't new as it was used in the previous Tartherzeal 5, I just have not had much experience with it since running in the Tartherzeal 3.  This is not a cushioned ride, but firmer and faster without being bone shattering.   The midfoot trussic system that is classic to (most) Asics shoes is also present.  While this version is called the propulsion trussic, it does not extend into the forefoot as seen partially in the DS Trainer.  This leaves some flexibility present in the forefoot, which some may or may not like.  Personally I was a little disappointed as I was hoping for a similar design to the DS trainer, which would be a go to shoe for me if it wasn't so narrow.   However, thanks to the Flytefoam and the amount of forefoot grip from the DuoSole, the Asics Tartherzeal 6 still has the responsiveness up front that I crave in racing shoes.   Like many Asics shoes, the heel is not beveled.  Perhaps due to the slightly more forgiving sole, I have not had as much issue with this shoe except after long miles when I fatigue.  So for those sensitive to a lack of a heel bevel, be aware looking at this shoe.  

There is a 10mm drop, as with many traditional Asics racers, although it feels slightly lower than that.  This is one of the lighter high drop shoes, so for those that need that but want a lighter weight (5.6oz) this is a great shoe to check out.  I was blown away by how light these shoes feel on the feet and am impressed they were able to bring down the weight even more from the previous versions!


STABILITY

Thanks to the stiffness of the trussic system slightly overcoming the narrow midfoot last, the Tartherzeal feels fairly average when it comes to stability shoe.  For those with excessive pronation or motion at the rearfoot/midfoot, while the firmer ride provides more stability, this may or may not be enough stability for you.  There was a previous version of the Tartherzeal called the Tartherzeal TS that had a post in the forefoot.  While it appears to have been discontinued, I am still trying to find a pair to report on forefoot posting in a racing shoe (was also done in of the original versions of the Adidas Adizero Mana).  


SPEED

This is a shoe meant for speed.  With the propulsion trussic and firmer ride, the shoe fairs far better during speed workouts and races.  I prefer a little more shoe for tempo runs, but many people used to lighter shoes would be fine.   Race wise I could see myself using these definitely for the 5k-10k and up to the half marathon.  Many individuals will easily be able to use this up to the marathon and beyond, especially getting the wider width from Japan.  


DURABILITY

The DuoSole outsole is one of the more durable soles I have seen in racing flats.  I have had next to no wear over the 28 miles fast miles I have put on these.  I was really concerned with the nubs in the forefoot, but none of those have come off thus far.  The traction is extremely high in the Tartherzeal 6 thanks to those nubs.  This is especially noticeable on the track where these nubs easily dig in and feel like track spikes.  


THOUGHTS AS A DPT 

I mentioned above in the stability section that the trussic system stiffness influenced the stability of the shoe.  I should note that there is no published literature that torsional stiffness of a shoe is required for stability of a shoe or increases the relative stability of a shoe on a measurable level (other than perceived).    There is a few studies linking increased stiffness of a shoe or foot to performance (Butler, Crowell, Davis, 2003; Roy, J. & Stefanyshyn, 2006; Stefanyshyn & Nigg, 2000) , however it seems  that stiffness prevents the loss of energy rather than enhancing performance.  Additionally, there is some evidence that foot stiffness is far more important and there is a sweet spot of shoe stiffness (Oleson, M., Adler, D., Goldsmith, P. 2004; Stefanyshyn & Fusco, 2004).  Too much limits motion excessively, too little may cause energy loss.  

The crossed pattern of the trussic system of the Asics Tartherzeal 6 is somewhat similar to many of the plantar ligaments of the foot.  

So all the comments about midfoot trussic systems increasing stability is not supported by any current literature.  Which is one of the reasons they are slowly dying out.  Even Asics has several shoes without any midfoot device present currently.  As one of the studies above mentioned, the stiffness of your foot may be far more important, so although I am biased as a DPT, it may be more important to work on your foot strength and stability (For more information, READ THIS)!


WHO THIS SHOE IS FOR (Conclusion)

This is an extremely fast shoe meant for those looking for a lightweight, high drop shoe for the 5k all the way up to the marathon (half marathon for most).  The fit is adaptable, but will work best with about a 1/2 size up (not for all).  The Flytefoam midsole is less harsh than my previous experiences with Asics racers but still just as fast, especially with the propulsion trussic.  The stability is decent for a racing flat and the durability appears to be above average.  Although it has limited availability in  through the US, this is another Japanese racer well worth looking into.  This is a classic Asics Japan racing shoe that those looking to run fast should experience.  I hope however that in the future, Asics considers redoing their trussic system to extend into the forefoot.  Or like many of their recent releases, including the Cumulus 22, consider getting rid of it for something else..  

GRADING

Fit/Upper          7/10  (minus points for short fit)
Ride/Midsole    8/10 (minus a few points for lack of extended trussic system)
Stability            8/10 (minus a few points for normal narrow midfoot of racing shoe)
Speed                9/10 
Durability          9/10

Total Score:  84% - Definitely worth checking out!

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.


Matthew Klein, PT DPT OCS
Doctor of Physical Therapy
Board Certified Orthopedic Clinical Specialist
Kaiser SoCal Manual Therapy and Sport Fellow

***Disclaimer: These shoes were provided at a decreased charge in exchange for a review.  A big thank you to Jorge Jabaz of the Valor Track Club (Asics) 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 10-25 miles on racing flats prior to reviewing them. Currently I have 28 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.

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References

1.  Butler, R., Crowell, H., Davis, I. (2004).  Lower Extremity Stiffness, Implications for Performance and Injury.  Clinical Biomechanics 18: 511-517.

2.  Mileer, J., Nigg, B., Liu, W., Stefanyshyn, D., Nurse, M. (2000).  Influence of Foot, Leg and Shoe Characteristics on Subjective Comfort.  Foot & Ankle International 21(9): 759- 767.  

3.   Oleson, M., Adler, D., Goldsmith, P. (2005).  A comparison of Forefoot stiffness in running and running shoe bending stiffness.  Journal of Biomechanics 38(9): 1886-1894

4.  Roy, J. & Stefanyshyn, D. (2006).  Shoe Midsole Longitudinal Bending Stiffness and Running Economy, Joint Energy and EMG.  Medicine & Sciences in Sports & Exercise 38(3): 562-569

5.  Stefanyshyn, D. & Fusco, C. (2007).  Increased Shoe Bending Stiffness Increases Sprint Performance.  Athletics, Sports Biomechanics3(1): 55-66

6.  Stefanyshyn, D. & Nigg, B. (2000).  Influence of midsole bending stiffness on joint energy and jump height performance.  Medicine & Science and Sports & Exercise 32(2): 471-476.