Does Hair Removal Actually Make Runners More Aerodynamic?
November 21, 2019
“To shave or not to shave?” That is the question for many runners and bike riders. Although limited testing has been carried out in response to this question, one test conducted by Mark Cote (a specialist in aerodynamics) has shown that shaving actually makes a difference to a runner’s velocity. To be precise, wind tunnel testing showed that cyclists could save around 15 watts (the equivalent of 60 seconds on a 40km time trial) by removing the hair on their legs. The testing is reliable, considering that wind tunnel tests enabled researchers to conduct their testing in tightly controlled conditions.
How Were the Tests Carried Out?
The tests were carried out on real cyclists pedaling through a wind tunnel. By testing several times under the same conditions, athletes were able to repeat the exercises, as well as a static mannequin, might. Previous testing using mannequins had actually come to very different results. A famous 1987 study by engineer Chester Kyle saw researchers using mannequins rather than human beings. The mannequins were put through a tunnel with hair glued on to their legs on some occasions to test if times were improved. In this test, there was a small improvement of around five seconds in a 40km trial. However, the use of non-human subjects, plus the fact that the wind tunnel was small, probably skewed the results. Today, scientists are convinced that shaving is indeed more than a fashion and should actually be considered by athletes wishing to slice precious seconds off their time.
Can These Results be Applied to Runners?
Although a controlled test through wind tunnels has not been carried out on runners, it is easy to see how the results are relevant. Aerodynamics is as much a priority for runners as it is for cyclists and indeed, wind resistance is one reason why so many runners choose to go hair-free. Possible skin issues such as razor bumps can be solved with heat, ice, and even tea tree oil. All-in-all, it can be said that shaving has a small downside compared to the potential benefits it can bring. Another study of swimmers showed similar results to those obtained by cyclists. The study, published by RL Sharp and DL Costill, found that removing body hair significantly reduced the rate of “velocity decay”. The secret is the ability of hair-free skin to reduce active drag, thereby reducing the effort required to achieve the same or better results.
It’s Not All About Speed
For many runners, one of the reasons for shaving is to show off the fruits of their hard work – i.e. their calf muscles and quads. However, shaving can also aid performance in indirect ways – for instance, by speeding up wounds caused by gravel rash. From a comfort perspective, shaving also works, since it makes it easier to don compression garments, enables easy application and removal of tape, and reduces pain and discomfort when legs need to be handled. In the summer, going hair-free can also feel cooler. In essence, achieving top performance isn’t always a matter that can be directly measured. It is the result of various factors, which can include confidence, comfort, and general wellbeing.
Although more research is required into the effect that shaving legs can have on runners’ speed and aerodynamic potential, the habit is pretty much standard for anyone who takes the sport seriously. From showing off well-defined calves to cutting off a few seconds from a run, shaving seems to be the wise choice for those wishing to err on the side of caution. Shaving does have its downsides, like razor burn, occasional bumps, and the like, but choosing the right hair removal method can help reduce any inconveniences to a minimum.
Photo by Stage 7 Photography on Unsplash