Is the Nike Vaporfly Faster?

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Nike’s carbon soled Vaporfly certainly has had it’s share of hype and great results.  But after getting a pair to polish my running speed right before nationals I questioned if they were faster.  And I worried about cramping or injury with new shoes, so I decided to race in my trusty Brooks Launch GTS.
 
Now that I’ve had time to do some speed workouts, my perception is that the Vaporflys are slower.  Compared to my normally silent foot strike, these shoes are loud and feel like clunkers.  My sense is that my cadence is slower, ground contact time longer, but with a longer stride, and roughly the same speed or slightly slower.
 
With a race coming up this weekend I decided to conduct a test.  I used our 4 x 800-meter Track Tuesday workout.  I would wear my Garmin HR strap to capture run dynamics.   The first 2 intervals would be in my favorite Brooks and the second two in the Nikes.
 
Test Day:  I met the Pain Cave crew and we were treated to another beautiful SW Florida morning.  No wind and about 70 degrees.  The first two intervals in my Brooks felt normal.  My legs were good, and I held back a touch from my 5K pace.  Between my 5K and threshold pace.  The splits confirmed this coming in at 6:07 average.
 
I switched to the Nikes and running the same perceived, effort and threshold heart rate I felt slower, lower cadence, with longer contact time.  But I was surprised to see a faster interval time. 
 
Test Data: Very interesting!  My cadence was slightly higher, not lower.  My stride length and contact time were too close to call.  And there was a very slight improvement in vertical ratio (a measurement of running efficiency).  BUT there was a noticeable improvement in speed!  My pace per mile was 15 seconds faster in the Vaporflys, 5:52 vs 6:07! 
 
Conclusion:  Frankly I was surprised by the test results.  But it’s a pleasant surprise.  The Vaporflys were 15 seconds per mile faster.  This is huge, and I’ll take it!  I suspect this is like riding with fatter tires and lower low pressure.  It feels slower, but it’s actually faster. 
 
One take away is that although Garmin’s run dynamics is an amazing tool the change in the metrics were subtle, and I would expect to see more change with an increase of 15 seconds per mile.  I suspect there is some other dynamic not being measured, such as rebound speed.
 
I do recommend getting used to these before racing in them.  Like any new gear you need some time to get in sync with the equipment.  But in this case the payoff should be worth it.
 
See you in the Pain Cave!
 
Coach GP