As World Athletics clarifies the rules on shoe technology in the face of the Nike Vaporfly controversy, a new University of Waikato study cautions the Vaporfly shoe may not actually benefit all runners.
University of Waikato researchers have published a report saying the Nike Vaporfly, worn by elite athletes who have smashed world records ranging in distance from 1500 metres to marathons, may not be all they’re cracked up to be for everyone, especially when used by recreational runners.
Researchers at the university’s Adams Centre for High Performance in Tauranga in collaboration with international colleagues from The Running Clinic in Canada, put 18 male recreational runners between the age of 18 and 59 through their paces wearing three shoes: the $380 Nike Vaporfly, the runners’ own shoes and pair of Saucony Endorphin Racer 2 lightweight road racing flats.
Waikato University’s Dr Kim Hébert-Losier said while the average improvement in running economy using the Vaporfly shoes was around 4 per cent when compared to individuals own shoes, which is consistent with Nike’s branding and claims, the most interesting result showed the Vaporfly shoes could also have a negative effect on running economy in certain runners, with one runner being worse by almost 9 per cent.
She also cautions a 4 per cent improvement in running economy does not mean a 4 per cent improvement in racing times.
“Up until now, all the studies in elite athletes have only shown benefits from wearing the Vaporfly shoe and no negative responders. Our research with recreational runners showed some runners did respond negatively to the shoes.”
She said runners that were fore-foot strikers or mid-foot strikers tended to not benefit as much from the Vaporfly shoe but the team of researchers from the Adams Centre planned to explore the results further, analysing the biomechanical data collected during the trials.
The Vaporflys, first introduced in 2016, use a combination of a new lightweight foam with a high degree of energy return, called Pebax®, which is fused with a curved carbon plate to create a ‘spring’ effect that ensures less energy is lost with each step.
The shoe has caused rancour among elite competitors and rival brands. Last month, World Athletics gave its seal of approval for the Vaporfly while announcing a moratorium on any further shoe technology advancements.
“World Athletics have reformulated the rules on shoes because of the world records that are being broken by people wearing Vaporfly. It’s been called technology doping, but our research shows there is other information in the mix. These shoes don’t benefit everyone,” said Dr Hébert-Losier.
While it was hard to refute the Vaporfly shoes did work to improve the running economy of some runners, she said the lightweight racing flats also improved running economy close to 4 per cent. The racing flats weighed much less. Research has shown that for every 100 g of weight removed from a running shoe, the runner gains about a 1 per cent improvement in running economy.
“In our trials we painted all the shoes black so the runners wouldn’t be influenced by the brands and we found that of all the shoes tested, the runners’ own shoes were actually the worst of the lot.” This finding has led to the hashtag #yourshoessuck.
Since being released online in preprint form, her team’s research has been downloaded more than 350 times and received close to 40,000 impressions from Dr Hébert-Losier’s post on twitter @KimHebertLosier
“Ultimately the biggest market for Nike is the general public, not elite runners. We’re saying if you’re an elite runner sponsored by Nike, good for you if you respond favourably. But, if you’re an everyday runner running to stay fit, keep in mind that the shoes might not work for you and that the $380 spent might not be worth it.”