Courtesy: Bruno Nascimiento
A new marathon shoe produced by Nike, the Vaporfly 4%, is causing controversy in the running community. As the name suggests, the shoe is said to improve speed by 4%, causing critics to question whether wearing the shoe is considered cheating.
Nike created the shoe for men to break the two-hour marathon time barrier at the price of $250. However, lab studies not funded by Nike have found that the name is credible and the shoes do improve speed by 4%. Constructed of a curved, carbon-fiber plate placed in the sole surrounded by lightweight foam, the shoe has been found to reduce energy expenditure in men running at the same pace. But critics were asking, does the carbon-fiber sole act as a spring, giving runners wearing the shoe an unfair advantage?
Two new studies, both published in Sports Medicine, have found that while the shoe increases speed, the sole does not act as a spring. The first study looked at men and women, all experienced runners. They were asked to run on treadmills for five minutes at an “easy pace” – 5.5 to 7-minute miles. Subjects either wore a pair of the Vaporfly shoes, Nike spiked track shoes or an Adidas marathon running pair. The runners wore masks that tracked their oxygen intake and the study found that the Nike Vaporfly 4% produced the most efficient run. Scientists assumed the lightweight nature of the shoe contributed, but they weren’t sure.
Another study conducted by researchers at the University of Colorado in Boulder had ten experienced male runners wear the Vaporfly, a Nike marathon shoe, and a similar Adidas marathon shoe. They filmed the men as they ran, finding that “the 4% shoe had slightly changed how the men ran, reducing the amount of muscular activity around their ankles and within their feet, lessening the amount of energy they burned with each step and making them more efficient.” Rather than acting like a spring, the carbon-fiber sole performs like a lever, allowing runners to push off with ease, reducing energy expenditure in foot and leg muscles. The foam also “absorbed and returned a portion of the energy the men generated with each step,” leading to decreased energy costs.
While these studies prove that the Vaporfly 4% increases speed for experienced runners, it is unlikely to do so for older or inexperienced runners. When looking to increase speed, proper nutrition and training are more effective.