Crossing the hills on new shoes

Crossing the hills on new shoes

In response to our earlier article about the Nike Vaporfly Next%, we got readers’ questions about whether we were going to buy them ourselves. Ron decided to do it, so he was ready with his brand new shoes at the start of Asselronde on Sunday February 2nd 2020. This road race over 25 km is part of the three-day running event Midwinter Marathon in the Dutch city Apeldoorn. The beautiful track leads through forests and heathlands and passes the Torenberg, at 107 meters just not the highest point of the Veluwe nature reserve. The weather conditions were favorable, with almost no wind and a little drizzle at 5 degrees Celsius.

Ron ran on the Nike Vaporfly Next% Ekiden, a version that has just been released. The version is intended as a tribute to the six-person marathon relay (Ekiden) in Japan.

World Athletics (the former IAAF) captured the news items recently on the rules for running shoes. The big question was whether they would ban the Vaporflys because of the special characteristics or not. It worked out well for Nike. Like other shoes with only one carbon plate, they are now officially permitted.

Starting area

As he entered the starting area, Ron met a running friend with the famous pink Vaporfly’s at his feet. Otto has had them for a while and told Ron that he had evaluated his running results in all sorts of ways, but found no significant positive impact on his performance. “They run very comfortable,” Otto said. And he’s right about that.

It is a fact that many elite athletes are running on Vaporfly’s nowadays. We saw that en masse at the Dubai Marathon, and earlier at the World Marathon Majors in 2019. Ten out of twelve winners at the Majors wore these shoes, both for men as well as for women. Meanwhile, the performance-oriented runners at the athletics clubs influence each other and buy the Vaporfly’s as well.

“Of course you run also quicker if it is just an idea in your head,” Otto commented.

Heading for 2:05

Early January Ron ran the 10 English Mile (16.1 km) of the flat Florijn Winterloop in 1:19:00. If you enter this result into the The Secret of Running calculator, the prediction for 25 km is a time of 02:06:31.  On faster shoes, 2:05 seemed a realistic challenge, even with the hilly course. It requires an average pace of 5:00/km. After deduction for a sanitary stop, Ron clocked 2:05:36 at the finish. Otto ran better than expected: 1:48:49 (4:21/km).

The additional power costs due to the hills

The objective was to stay close to 5:00/km and collect a lot of running data. In order not to waste energy, Ron ran a bit slower uphill and downhill a little faster. The readers of our articles and book The Secret of Running know that overall hills always cost a bit more power due to the fact that the muscle efficiency downhill is lower, so not all the gravitational energy is recovered.

The image with the height profile shows that the slopes change continously and so does the power required to run at a constant pace. The collected data can be used to calculate the average wattage required to overcome the climbing resistance.

On average the gradient was around 1.65%. Consequently, Ron (80 kg) had to spend an additional 20.8 Watts uphill. Downhill, he recovered some 18.0 Watts. On balance, the climbing resistance cost him some 2.8 Watts.

Image: height profile Asselronde (source: website Midwinter Marathon)

The additional power costs due to the wind

Wind has a similar impact as hills have. You benefit less from tail wind as compared to the the disadvantage of headwind, so overall the wind resistance leads to additional power costs. In this case the wind was barely noticeable and, moreover, rotated favorably. Only in the last kilometers the headwind was somewhat stronger.

At 12 km/h (pace 5:00/km), Ron’s air resistance (80 kg, 1.90 m) due to his ‘own wind’ (the wind caused by his running speed) is approximately 5 Watts. In the figure Stryd’s Air Power is shown for the length of the race. On average, the Stryd v3 (with wind port) recorded only 3 additional Watts of air power.

Image: Ron’s Air Power (Stryd view in Today’s Plan)

Was Otto right?

The above results seem to indicate only a slight improvement in performance due to the shoes. Ron ran about 1 minute faster than the prediction during a race which costed him an additional 6 Watts due to the hills and wind. So was Otto right in assuming that there is hardly an advantage in the shoes?

Considering the data, the shoes did in fact give Ron several advantages. Next to the minute faster while wasting an additional 6 Watts on wind and hills, he also found that his average heart rate (HR) during the race was considerably lower that than usual at this pace. According to his pace-heart rate relationship, his HR should have been at least 3 bpm higher. 3 bpm equals 10 seconds per kilometer for Ron, so this is equivalent to a benefit of 3%! It is unfortunate that Ron did not realize this during the race. He could probably have opted to increase his pace and run a faster time. He will try this at the next opportunity.

Is it because of this lower HR that the Vaporfly’s run comfortable, the legs get less tired and you feel energetic for a longer time? Does the carbon plate embedded in the thick solid foam ensure internal energy recovery, a more efficient running movement and thus a lower Energy Cost of Running (ECOR). Anyhow, the result fits nicely with the research that our friend Guido Vroemen did with a journalist at his exercise laboratory.


The shoes are comfortable. They are very much in demand. Results are impressive. How it exactly works is still the secret of Nike.

Our book ‘The Secret of Running’ is for sale in our webshop. Also available in German as ‘Das Geheimnis des Laufens’, and in Italian as ‘Manuale completo della corsa’.