Mizuno Wave Inspire 21 review

We enjoyed testing the Wave Inspire 21 and recommend it for:

• Runners who liked the previous version—it keeps the same ride with a better midsole.
• Heel strikers needing stability without a stiff, clunky feel and who value full outsole coverage.
• Those wanting more support than average daily trainers without going for overbuilt shoes.

We think the Wave Inspire 21 isn’t the best option for runners with a midfoot or forefoot strike. Its sky-high 12.7 mm drop favors heavy heel landings and works against a forward-leaning stride. Based on our findings, we believe models like the Saucony Guide 17 or Altra Paradigm 7 are far better suited for those with a different footstrike pattern.

Weight is another drawback we noted in the lab. For a smoother, faster and less bulky ride, we recommend exploring the Brooks Hyperion GTS 2 or the Hoka Rincon 4.

With a 38.0 mm heel stack, the Wave Inspire 21 continues to grow closer to the 40-mm threshold—offering generous joint protection for heel strikers, who remain the primary focus of this stability-oriented shoe.

The forefoot measures 25.1 mm, identical to what we found in the Wave Inspire 20 here in the lab. It offers enough foam to handle most runs and falls right in line with what we expect from a road daily trainer.

The Wave Inspire 21 sticks to the formula of its predecessor with a massive 12.9 mm drop. In our view, it's a shoe clearly designed for heel strikers or those who benefit from this kind of high-offset, less-natural geometry.

Now to the midsole. The Wave Inspire 21 comes with a dual-foam setup combining Enerzy and Enerzy NXT.

Enerzy is Mizuno’s older, durability-focused foam that feels a bit flat underfoot, while Enerzy NXT is a fresh-and-snappy upgrade that we’ve already tested (and loved) in models like the Neo Vista. We measured the Enerzy layer at a firm 26.6 HA, which fits the shoe’s goal of providing a steady-and-controlled ride rather than cloud-soft landings.

The secondary foam is the one that hits the ground first and is a variation of Enerzy NXT that's also adjusted to boost stability and limit side-to-side movement. We measured it at 19.3 HA, which adds a touch of plushness, though the ride still feels on the firmer end.

We put the Wave Inspire 21 next to our mochi ice creams for 20 minutes and found that it got 19% firmer. Not a bad outcome!

We found that Mizuno added a 5.4 mm EVA-based plush insole to boost the cushioning in the Wave Inspire 21.

We discovered that the Mizuno Wave Inspire 21 stays true to its heritage by skipping an aggressive heel bevel or forefoot rocker, something we truly value in a market crowded with rockered running shoes.

Both curvatures are modest and non-intrusive, letting the high-drop geometry do the forward-driving work for heel strikers.

The Wave Inspire 21 sticks to its signature setup with a partial plate tucked in the heel to control landings in that zone. It's one more reason why we're certain this shoe is made for rearfoot strikers.

We will also use this photo to show the deep lateral decoupling groove in the heel, which allows the rearfoot to compress independently and improves torsional flexibility too. Paired with the Wave Plate, it balances impact control with a stable, well-cushioned ride.

We crafted a gel mold of the shoe to discover how it fits, and we discovered that the interior of the Wave Inspire 21 offers solid space for those with broader feet, especially during longer runs.

In our first measurement, we registered 98.4 mm of width, which clearly beats the average and makes this shoe a wide-foot-friendly option with a generous midfoot platform.

We performed a second measurement in the big toe area, and this time it came up as an average 73.5 mm. That’s not hyper-generous like the Topo Atmos, but still a comfort-ready fit for most runners.

We finished the trifecta of measurements regarding fit with the toebox height.

There’s plenty of upward space with a vertical clearance of 30.9 mm, a design ideal for runners who hate pressure, especially around the big toenail.

Whether the roads are dry or wet from yesterday's rain, you can rely on the Wave Inspire 21 for great grip on both.

To mimic running on wet road, we applied a force of 500N to the shoe's forefoot (because that's where the push-off happens) at a 7-degree angle. Brushing the shoe's outsole against a slab of wet concrete, we recorded a solid friction score of 0.50. This is a solid result for a road running shoe.

The X10 outsole features full-length rubber coverage in a segmented layout. The forefoot and rearfoot include diagonal lugs separated by thin flex grooves. A deep central channel runs from heel to midfoot, aiding compression and movement plus exposing the blue Wave Plate.

For those seeking durability, this is a great option, as most brands are reducing outsole coverage. However, it will likely take a toll on weight.

During our test runs, we discovered that the WI21 delivered is stable as a table—especially for heel-first landings. Rather than relying on old-school stability elements like firmer inserts, Mizuno used its signature Wave Plate, which adds structure without making the shoe overly stiff.

Indeed, we twisted the Wave Inspire 21 and measured a 3/5 torsional rigidity—more in line with neutral daily trainers than stability models. Mizuno achieved this by using a heel-only plate, keeping the rest of the shoe pleasantly flexible.

The heel counter leans closer to classic stability designs with a firm 4/5 rating. It’s not uncomfortable thanks to the generous padding, but runners who prefer highly-flexible heel counters might find it a bit too rigid.

One simple way to enhance stability is by widening the midsole, giving the foot a more grounded feel on each landing. That’s exactly what Mizuno did with the Wave Inspire 21, reaching a broad 118.1 mm in the forefoot.

The same design logic applies to the heel, which measures a generous 94.0 mm—clearly wider than average. This was key, as we believe that 9 out of 10 runners using this shoe will be landing on their heels.

Any shoe aiming for all-day versatility needs a bit of flex—otherwise, it won’t feel right for hitting that 10K steps goal around town. Luckily, thanks to its short-length Wave Plate, the Mizuno Wave Inspire 21 delivers with a 14.5N result in our bend test.

One thing that really stands out while running in the Wave Inspire 21 is that it doesn’t feel lightweight at all—mainly because of its full-length rubber coverage. Still, its 10.1 oz (286g) isn’t bad at all, showing a 5% improvement over its predecessor and closing the gap to the average.

Instead of using a classic engineered mesh, Mizuno went with a jacquard mesh that doesn’t feature any large ventilation holes. That immediately raised questions for us about how breathable this shoe would be.

To get a clear answer, we used our smoke machine and, unfortunately, the result was slightly below expectations. It scored a 3/5, which isn’t a major issue for most runners, but we were hoping for stronger airflow.

We then placed the upper over a bright light and quickly noticed that there wasn’t much space for air to escape. Because of this, we believe it might get a bit warm on heat-wave summer days.

The upper feels solid and the material is comfortable against the foot, yet the micro-openings we spotted under our microscope appear too small to truly help with ventilation.

We also checked the padding. There’s a satisfying amount in both the tongue and heel, giving the shoe a soft-cushioned feel.

The absence of large ventilation holes turned out to be an advantage in our Dremel-based durability test, as we gave the Wave Inspire 21 a 3/5. It’s not an award-winning result, but still solid for everyday miles.

The same story unfolded with the heel padding durability—this Mizuno outperformed the average and earned a solid 4/5. Once again, there’s no reason to be concerned about early signs of wear.

We were also pleased with the outcome when we tested the outsole using the Dremel: only 0.9 mm of damage. Staying below 1.0 mm usually means there's enough durability, especially for a shoe with generous coverage.

To be absolutely sure the Wave Inspire 21 holds up over time, Mizuno added 4.5 mm of rubber beneath the foam. For us, that feels a bit much—this shoe already leans heavy, and something closer to 3 or 3.5 mm would've struck a more reasonable balance.

The market is red-hot right now, and any overpriced daily trainer usually struggles to sell. That’s why we found that the Wave Inspire 21 held its ground without a price bump, maintaining a value-focused position.

We found a few small reflective elements on the upper, but we believe Mizuno could step it up with a more hi-vis design.

The lacing system on the Wave Inspire 21 reflects a no-nonsense approach with simple punched eyelets and flat shoelaces deliver a secure fit without gimmicks.

The tongue keeps the same structure from the previous version with 6.9 mm of padding, and we understand why. We tested it and found that it offers a confident lockdown without resorting to a super-thick, overcushioned slab that might feel plush at first but often overwhelms later.

The tongue is partially fixed to the sides—just enough to enhance the lockdown with a more secure, movement-free feel.

The heel tab uses a tall, pull-friendly collar—similar to what we’ve seen in some Hoka models—which can be easily grabbed to help slide your foot in with less effort.

The stock insole removes effortlessly, making it easy to replace with your favorite insert. There’s enough space in the upper to accommodate most alternatives without causing any tightness.