Asics Piranha Sp4 Review for Forefoot Running

More and more runners are switching to minimalist running to restore foot strength and run with better performance. New research proves that flat, minimalist, barefoot-like running shoes allows more elastic energy storage and release in the Achilles tendon and the foot arch (Perl et al. 2012), therefore making running more energy efficient.

And, another obvious way minimalist footwear improves run performance is because these shoes are lighter than the typical running shoe whereby a lighter running shoe reduces the cost of transport on the leg during running, and that’s great news!

But to get the most out of your minimalist shoes, you need to utilize a forefoot strike landing when you run, and more notably, the shoes MUST feel comfortable and be flexible.

Asics Piranha Sp4 Review for Forefoot Running

In a recent study by Fuller et al. 2016, minimalist running shoes improved performance over a 5 km distance –this was expected because of the lightness factor, but for significant improvements in running economy, minimalist footwear really works to your advantage if you run with a forefoot strike.

In their study, the researchers compared the effects of minimalist footwear (Asics Piranha SP4 — 5mm heel drop–shown below) vs the conventional running shoe on running performance during a timed trial in trained distance runners who were unfamiliar with wearing minimalist footwear, and who were heel strikers.

Asics Piranha Sp4
The minimalist shoe used in the study, the Asics Piranha SP4

Asics Piranha Sp4 Minimalist Running Shoe

The researchers measured running economy via oxygen uptake. The researchers also examined foot strike as an economical factor as well as perceived comfort. The researchers found that the minimalist running shoes resulted in a 22-second time trial performance improvement because of the lightness of the shoe, AND because the runners reported feeling more comfortable in minimalist footwear.

Interestingly though, one participant stood out from the rest of the minimalist shoe-testers. The participant who used the least amount of oxygen, was also the only one in the minimalist running shoe condition who landed with a forefoot strike whereas the others maintained a heel strike. However, the minimalist shoe testers had a reduced stride length and increased step rate, especially at faster running speeds of 13 -15 km/hr, but only trivial decreases in stride length and step rate at speeds slower than 13 km/hr.

Overall, the researchers concluded that a runner can certainly expect at least a 2% boost in run performance while wearing minimalist footwear, even without prior experience to this shoe type.  However, a different reason as to why the minimalist shoes boosted performance was identified in the study: the minimalist shoes helped runners run faster because the shoes felt more comfortable despite having less cushioning/under-foot protection than the conventional running shoe. You are more likely to run slower if your feet are sore and achy –this isn’t a surprise. The researchers concluded that the most economical runners wearing the minimalist shoes reported the highest level of comfort, too.  If running shoe discomfort is causing your performance to suffer, than switching to minimalist shoes can be helpful, as per the results in the study.

Have you ever worn a running shoe where it felt incredibly good to take the shoe off after running or walking long distances? Your shoes shouldn’t make your feet feel this way, rather your footwear should feel like an extension of you and NOT make your feet ache. This is why minimalist shoes have been well-received by the running community because these type of shoes are a more natural substrate for the foot.

Bare in mind, that your minimalist shoes don’t need a lot of cushioning to give you comfort. Many natural runners report that their feet prefer running shoes that feel like they are barefoot.  For some reason, the feet unleash physiological stress when an overly-cushioned shoe is worn and because of this, the feet are more prone to injury and also, poor nerve function.

More From Run Forefoot:

Good Running Websites About Barefoot Running

Benefits of Running Without Shoes

Barefoot Running Training Information

Running Advice on the Forefoot Strike


Fuller et al. Effects of a minimalist shoe on running economy and 5-km running performance. J Sport Sci, 2016; 34(18):1740-1745.

Perl, D. P., Daoud, A. I., & Lieberman, D. E. (2012). Effects of footwear and strike type on running economy. Medicine & Science in Sports & Exercise, 44, 1335 – 1343. doi:10.1249/MSS.0b013e318247989e

Bretta Riches

"I believe the forefoot strike is the engine of endurance running..."

BSc Neurobiology; MSc Biomechanics candidate, ultra minimalist runner & founder of RunForefoot. I was a heel striker, always injured. I was inspired by the great Tirunesh Dibaba to try forefoot running. Now, I'm injury free. This is why I launched Run Forefoot, to advocate the health & performance benefits of forefoot running and to raise awareness on the dangers of heel striking, because the world needs to know.
Bretta Riches

P.S. Don't forget to check out the Run Forefoot Facebook Page, it's a terrific place to ask questions about forefoot running, barefoot running and injury. I'm always happy to help!