How Wind and Drafting Influence Your Performance

How much energy can you conserve by tucking in behind someone else during a race? More than you might think. Drafting is well-known in cycling, where the energy gain can be significant, but even in running, air resistance and wind play a role. The question is how big of a role it plays and whether it's worth considering your tactical position in the field. In cycling, energy savings often fall between 20–40% when riding in a pack, which you can read more about in our Vätternrundan article or take a look at this study. However, even though air resistance accounts for a smaller portion of the energy cost in running compared to cycling, the right positioning can save enough energy to make a difference in the final kilometer of the race. 

During a 5000-meter race, the energy cost to overcome air resistance accounts for about 2% at a 6 min/km pace and 8% of the total energy expenditure at a 3 min/km pace (1). If we compare treadmill running and outdoor running, running on an indoor treadmill with a 1º incline roughly equates to outdoor running in terms of energy cost. This incline approximately compensates for the additional energy that air resistance requires outdoors at speeds between 10-18 km/h on the treadmill (3).

Don't underestimate the role of wind in running!

The energy cost of running naturally varies with body weight, running economy, and other factors. But generally, the air resistance increases exponentially as your running speed increases: if you double the speed, the energy cost to overcome air resistance quadruples. When the air resistance gets larger (faster speed or stronger headwind), we often lean forward into the wind. This creates some lift that partially "lightens" our body weight, which means the energy cost doesn't skyrocket as dramatically as raw numbers might suggest.

However, air resistance still constitutes a relatively small part of the total in running, about 4–8%, which can be compared to cycling where air resistance accounts for 80–90% of the total energy cost (4).

That's exactly why we're writing this article.

If you hang back a few steps in the pack, you'll conserve a lot of energy compared to leading at the front. The energy saved can be between 2–4% at medium and long-distance paces. It might seem small, but pacing yourself strategically and conserving energy for as long as possible puts you in a much better position for a strong finish. This energy savings is equivalent to speeding up by 5–10 seconds per kilometer if you're running at a 4 min/km pace (15 km/h). Further calculations show this translates to a time gain of about 1–2 minutes per 10 km. And all it takes is avoiding being the leader of the pack. Who hasn't heard it's easier to chase than being chased? 🙂

If we're diving into the details, record-breaking attempts are often carried out as close to the equator as possible, where Earth's gravitational pull is slightly weaker. In studies conducted before the Sub2h marathon attempt, this factor was taken into account. Compared to Berlin, the gravitational pull is 0.31% weaker at the equator. Supporting one's own weight while running, meaning staying upright, accounts for 74% of the energy expenditure during a run. With a 0.31% reduction in energy required to maintain body weight, we save about 0.23% in overall energy consumption, which their calculations suggest corresponds to roughly 17 seconds in a marathon. Sure, the Monza track is closer to the equator than Berlin, but it's still quite a distance away. One issue there is the generally higher humidity and temperature, so the negative effects likely overshadow the minor positive impact of reduced gravity.

PS: Don't forget to sprint at the end so you win the race anyway!