How does running in an inside or outside lane affect the track? How is it better to take turns during a marathon for a more efficient run?
In the article we will answer these questions with the help of physics!
In Athletics track, running a sprint or a middle-distance race in lane 1 or lane 8 makes a big difference! This because when we run around corners the physical forces that oppose the propulsive force come into play, slowing us down and increase the effort required maintain our ideal speed.
In fact, in the 200 and 400 meter track racesconsidering that the route also includes bends, the start of the athletes placed in the furthest lanes is further forward by a few meters than the innermost lanes, so that everyone travels an equal distance regardless of the lane they are in.
In theory, this technical device, the so-called “Gap”should also serve as a compensate for the greater propulsive power enjoyed by athletes competing in the outer lanes.
Running around the bends: what forces come into play
There are three main forces to take into consideration when riding around corners:
- propelling force: the force that the runner is able to generate to push himself forward. This will depend on both the athlete’s weight and muscle mass.
- resistive force: is the set of factors that act contrary to the driving force, causing the runner to slow down. Running surface, gradient, wind, altitude… so many factors that can help increase resistance. A standard value under unchanged conditions corresponds to a slowing down of 1 / 0.44 seconds.
- Centripetal acceleration: the force generated by bending, which tends to alter rectilinear motion. This force also intervenes by decreasing the propulsive force of the pad.
To understand how these three forces interact, it is also essential to measure the extent of the curve, to define its radius of curvature.
Understanding the radius of curvature in running is very simple when it comes to running on the track, because the trajectory is limited to the width of 1.22 m of each lane.
Here we can see how the lane number affects the radius of the curve. The higher the lane number, the higher the radius of curvature.
How to calculate the effect of curves on speed
This formula defines how the speed of the runner varies with respect to the curve he faces while running.
From here we can see how the centripetal acceleration, made up of the speed squared to be divided by the radius of curvature traveled by the slider.
Centripetal acceleration and deceleration
So, the smaller the radius of curvature, the greater the impact of centripetal acceleration, which will escape the propelling force of the skate during curve travel. L’effect of centripetal acceleration and the to slow down for this reason I am higher in the innermost waysthose with a smaller radius of curvature.
Using this formula we actually find that a running runner 200 meters in lane 1 in 19.72 seconds would run the same distance in lane 8 with a time of 19.60 seconds.
Curves and racing on asphalt: some advice
Calculating the influence of turns on our speed becomes more complex when it comes to riding on asphalt. Indeed, the trajectory of the curve is very variable and the radius of curvature is not so clearly definable.
From the speech given before we can still draw some advice!
Racing on asphaltespecially on longer distances such as marathons and half marathons, if you want to navigate curves more efficiently by covering the shortest distance, the advice is to follow the tangent of the curvefollowing a straight trajectory that comes as close as possible to the innermost point of the curve.
Physicist and biomedical engineer
Friend of LBMsport and runner
See Sandro’s notes