Mizuno seems to reserve all of their really cool shoes for markets outside of the US and we haven’t had chance to review a lot of them lately in general. It goes without saying we were excited to get a chance to check out their new Wave Sky 4 WAVEKNIT which is an everyday road shoe design for runners who just want a simple single shoe and aren’t looking to take things too fast. With the Wave Sky 4 you should expect durability, cushion, comfort, and a little bit of pop from their new midsole tech.
Quick Details, Specs, and Availability
- An everyday runner with a focus on cushion and durability, but it’s also a touch heavy.
- Weighs in at 11.2oz or 318g for a US Men’s 9, 9.4oz or 266g for a US Women’s 7.
- Features 33mm of cushion and has a 10mm heel/toe drop.
- Retails at $160.00 USD and comes in 4 colors for Men and Women.
Run Test
We actually ran in a lot of Mizuno a few years back, and the first thing you will notice with the Wave Sky 4 is that it truly doesn’t feel like a lot of Mizuno shoes you may have tried prior. This has a wider stance overall, the upper is roomier and the use of knit instead of mesh will feel very out of character for Mizuno traditionalists, but it’s actually quite nice in terms of fit and feel. The other thing we noticed right away is that the upper actually comes up a bit higher than other running shoes, just a touch, but it is enough to be noticeable and will definitely deter some people as it can irritate depending on your anatomy.
First time on the foot, you are going to love the upper feel. The knit is on the heavy side, and definitely insulates so depending on climate can run a little warm, here in the Pacific Northwest winter and fall it’s all good. The bootie design and gusseted tongue are soft and envelopes your foot really well, once in there it holds you comfortably. We would put these next to a Brooks Ghost, Saucony Ride, or Asics Nimbus in terms of comfort in the upper. That dual-density midsole feels soft at first, but not too soft, but it is very clear but the shoe is just too heavy as that excessive outsole material just wants to pull you to the ground.
In a run, the shoe doesn’t change much at all from that first experience. That upper is very comfortable and there’s really solid flex in terms of the way they designed the midsole and the grooving they put in the outsole. The Mizuno Enerzy actually does give you a pretty solid amount of bounce, but the shoe is betrayed by its weight because inevitably if you were thinking about using these for distance then your legs just get tired. Even when running these for a half marathon, by the end that 2-3oz difference becomes noticeable.
That being said, if you are an everyday 5-mile runner who takes it really nice and easy, then the shoe feels really good. The upper material is comfortable and the heel cup holds you well and there’s decent enough cushion to leave your legs feeling fresh. It’s when you start to go longer where the issues arise, so really take that into account before considering. It’s a nice-looking shoe and the tech is solid, we only hope that in the next iteration they can tighten things up a bit and bring it down by at least 1.5-2oz.
Construction: Upper
The upper on the Wave Sky 4 uses their new WAVEKNIT which is a tightly woven knit material and it does feel really nice against the foot. Our only drawback here is that it is a very thick knit, so it can run a little warm depending on the weather. The gusseted tongue delivers a booty style fuel to the shoe and does a good job preventing lace bite even though it is only lightly padded. The collar is well-padded and the heel counter is rigid so expect a nice firm hold and protection of that Achilles.
That tightly woven knit upper 
Solid lacing system and the tongue is very nice 
Well padded collar and tongue gusset system
Construction: Midsole
The dual-density midsole is a blend of Mizuno technologies. The first layer uses their Enerzy foam which is all about the balance between firm and soft. They then use U4icX which is supposed to be more cushioned than prior iterations and should deliver a softer feeling underfoot as well as a smoother transition throughout the gait. The strobel board is made of the same technology. So clearly the focus here is on a softer feeling overall.
Midsole – lateral rear 
Midsole – lateral front 
Midsole – medial front 
Midsole – medial rear
Construction: Outsole
The outsole on the Wave Sky 4 is, as we mentioned, very thick and in that, it is also very durable. Their X10 outsole uses a carbon-based rubber that will stand up to just about anything and then Mizuno has also added flex grooves to the outsole which allows for better forefoot flex during the stride. If we are honest, these things can almost act as a light trail shoe given the robustness of this outsole.
The really thick carbon rubber outsole
Style & Aesthetics
The Wave Sky 4 is a good-looking shoe and we especially enjoy our blue review color as well as the gray and yellow combination. The upper styling is effective, but it does get very aggressive looking as you get to the outsole. It definitely doesn’t scream performance, but as an everyday neutral shoe will fit in very well with others at the same level.
Overall Conclusion
The Mizuno Wave Sky 4 WAVEKNIT is a real challenge for us. A lot of what they have added, especially in that upper and with that Enerzy midsole, makes the shoe really appealing. However, it is incredibly heavy for a daily road shoe. Most runners are now looking for something right around the 10oz range as their base. Here even at a size 9, you are starting at over 11oz and that’s going to be unappealing for a lot of people. As Mizuno looks forward to the Wave Sky 5, they really need to lighten things up. They can remove 50% of the outsole rubber both in terms of height and the location of the rubber, using more strategic placements would make it a much more compelling everyday runner.
