Which shoe is faster: Asics Nova Blast vs. Nike Zoom Fly 4

Run economy comparison among different types of training/racing super shoes.

Today is the first entry of an ongoing project in which I'll be testing & comparing how different types of training or racing "super shoes" affect run economy and mechanics.

First, let's define what I'll refer to as training or racing "super shoes." These are sneakers with specialty materials such as foam to increase the energy return of your stride, shoes with carbon/nylon plates, or a shoe design with a heel stack of ~4-5 mm.

Second, I'll measure the volume of oxygen utilized at a given speed expressed as milliliters per minute normalized by body weight (ml/min/kg). And run economy defines as the milliliters of oxygen per minute normalized by body weight and speed (ml O2/kg/km). In addition, I'll share energy expenditure estimates and metrics like Heart Rate, Perceived Exertion & Run power.

Lastly, I'll share run mechanics such as stride per minute, vertical oscillation, ground contact time, and slow motion video comparing how/if a particular shoe alters the runner's gait.

Let's dive into today's comparison: Asics Nova Blast vs. Nike Zoom Fly 4 female version.

The Ascis Nova Blast is what I call a trainer shoe. The midsole design takes inspiration from a trampoline with what Asics calls a Flytefoam Blast to give the shoe a responsive and soft feeling underfoot. The shoe weighs -9 oz and comes with a heel drop of 10mm and a heel stack of 41mm.

The Nike Zoom Fly 4 is a maximalist trainer shoe. The foam is firm yet dense; although soft, it's not as bouncy or soft as other Nike super shoes. It also has a rigid the carbon plate with a unique forefoot which is angled upwards and not rounded. It can give a feel of lower effort for a given speed. The shoe weighs 9.6 oz. and comes with a heel drop of 8mm and a heel stack of 39mm.

The female runner described the Asics as comfortable/soft, and the rate of perceived exertion (RPE) yielded a 3 (on a 1-10 scale), while she described the Zoom Fly as soft but "bouncy," yet more responsive with an RPE of a 3. After the test, the runner mentioned that while both had the same RPE, the Zoom fly felt a bit easier to run.

You can see the details below regarding testing protocol, but we did three times 5 min steps for each shoe running at 7.6 mph on a treadmill at 1% grade. We alternated the order through the steps, and for VO2 and economy, we took the data for the last minute of each step and averaged it among all three efforts.

As expected, the Zoom Fly 4 resulted in a lower oxygen cost and better run economy. It means it can potentially save ~60 kcal per hour (the equivalent of half a gel per hour)

In terms of mechanics, the main difference between the shoes was that the Zoom Fly resulted in a lower stride per minute but a longer stride length and higher vertical oscillation. Most likely as a result of the carbon plate.

Other markers like power and Heart Rate were close to one another, though the runner's breathing frequency (breaths per minute) was slightly lower, which resulted in lower ventilation.

A somewhat surprising finding was how the Nova Blast affected her natural gait. The runner is a mid-foot-striker, but when wearing the Asics, her foot point of contact was heel-strike.

In summary, the Nike Zoom Fly 4 resulted in a lower running economy/energy cost for this runner, which was an expected result given its features, such as the foam/carbon plate combo. Still, the Nike design suits the runner's mechanics better based on the data recorded and her subjective measurements.

It doesn't mean the runner should stop using the Asics, though she could try correcting her stride when running with those to match her natural forefoot strike.

Next time we’ll test some trainer vs racing super shoes!