Do you have to run at a 180 steps per minute Cadence. There is a lot of confusion about this topic. Hopefully you’ll get a better picture by the end of this post.
Before giving you the explanation I need to dig into running form.
- True or False? do you HAVE to land right below your center of gravity like every one claims ?
The runner’s body in motion is like a human slingshot. When you try to throw a projectile using a slingshot you pull the elastic band and release it. When you pull the band you are storing energy (called potential energy in Physics). When you release it, the energy becomes cinematic energy. To sum up you are storing energy during the first phase and releasing it. Same thing happens during running. When you land, at the moment your foot touches the ground it is storing energy. The weight on that leg/foot will go from 0 to 2.5 times your body weight. This loading weight does not happen instantly, it takes a fraction of a second until it reaches the max load (2.5 times your weight). It is at this exact moment that your foot should be under your center of gravity. Not before, not after. To make that happen you need to land slightly in front of your center of gravity (5-10 cm?) to give time to the loading phase. Then if done properly, you will “unload” the stored energy right under your center of gravity (so by the time it reaches about 2.5 times your body weight). So the answer to the question above is technically “False”, although you are landing very closed to it in reality.
- Vertical oscillation viewed on the sagittal plane, how much?
If you were to throw a stone as far as possible, what angle would you aim at? Let’s take the two extreme opposite. If you shoot really high up in the sky, the stone would go high but would not travel very far. On the other hand if you throw your stone in a direction parallel to the ground you would throw it further but it is still not optimal right? We all know intuitively that the right way is somewhere in the middle, the stone will have a parabolic trajectory and the angle should be around 45deg ish. It is same for running, you want to propel your body forward as efficiently as possible, and to do that the angle between the ground and your foot during toe off should come close to 45 degrees. So if we were to draw a line representing the movement of your head when watching you from the side (on the sagittal plane) we should see an oscillation that is not as flat as some people are claiming. If that line is flat, you are just throwing your stone horizontally, if the amplitude is to big, you are jumping too much at each stride.
So what all this has to do with 180 cadence?
Well 180 cadence contribute to the above. It is the result of an efficient running form. Being efficient makes you run at around 180 cadence, not the other way around. The original observation came from researchers looking at the cadence of a pool of Olympians and they’ve noticed that the average cadence was 180 with a very low standard deviation. Running at 180 will force you to land closer to your center of gravity and will force you to push off the ground at the right angle, if your cadence is higher than 180 you would understride and move too horizontally, on the other hand if your cadence was significantly lower than 180 you would tend to overstride, jumping too much. Does that mean having a cadence of say 186 or 173 a disaster? of course not ! there’s a margin of error as everyone is unique and has a unique morphology. Your gait has to feel natural. But the bottom line is that too high above 180 or too low will have loose running economy.
- Is it better too high or too low?
In terms of efficiency there is no so much difference. But from an impact standpoint and injury prevention, because a lower cadence will have a tendency of getting you landing further from your center of gravity, you would increase the loading impact on your leg, thus creating more stress. When we get tired we tend to rely more on what we are good at. Which one is easier? kicking in front of you? or behind? You got it. For many of us, our front is stronger than our back muscles, we are quad dominants mainly because having a desk job and sitting all day long does not help. When we get tired during a run, or at the end of an interval, we tend to overstride, to reach further out because that’s more intuitive but unfortunately not more efficient. We then land too far out from our center of gravity and the runner has to “unload” the energy while the foot is still in front of the center of mass, costing much more energy as we are creating an unwanted breaking force at each step. You get this double whammy effect of fatigue + diminished running form efficiency. If you watch the best kickers (Bekele, El guerrouj, gebrselassie etc) at the end of their race of a track event, you will see that they are not overstriding, they increase their cadence big time !!!
So if you kickdown to kick ass, move your legs faster !!