Let’s start with what this means. Vertical oscillation is the upward movement of a running step, a running motion, measured in centimetres. If the vertical oscillation is between 5 and 10 centimetres, that’s good on average, if it’s more or less than that, you’ll want to work on it. This post is about why vertical oscillation is important for running efficiency, how it can be measured and how it can be changed to an optimal value (if there is an optimal value.)
Why is vertical oscillation important?
The running stride consists of two directions of motion. One is forward movement and the other is upward movement. The two motions interact with each other. If we don’t move upwards, we can’t move forwards either, as we need to be in the air to move forwards. At the same time, if we jump too high, we have less energy to move forward. In other words, if we want to run optimally, we need to control the upward movement. If the vertical oscillation is too small, too low, you are likely to step too small, have a longer contact with the ground, shuffle instead of run.
You can say that it doesn’t matter to you, you just want to run and it’s OK if your running is not optimal. It may not be a good idea to think that. Of course, optimal running is not about running nicely, it’s about using less energy so you can run faster and/or longer with the same amount of energy. In addition, too high a vertical oscillation can cause injury. The higher you “fall” from the ground, the harder you hit your feet (heels, mid-foot, toes, depending on your grip). If you have too little vertical oscillation, it means you are putting little energy into kicking off, your stride is weak (shuffling instead of running), which you need to work on, you need to strengthen your footing (you need to train more)
How do you measure vertical oscillation?
You can use different tools to measure vertical oscillation, but you can also video yourself running and use that as a basis to determine your vertical movement.
Many running watches measure vertical oscillation, if you don’t have one, you can buy a device that can measure the different properties (running dynamics indicators) associated with running motion. I use a Coros Pod, which tells me 5 other important running dynamics data about my running in addition to vertical oscillation.
Before you buy a new watch or a new gadget, you should make sure that you don’t have to worry about your vertical oscillation at all. Video record your run and watch it back (you might look lame if it’s the first time you’ve done this. Relax everyone goes through this). Chances are you’ll see on the video if you jump too high. If it’s not obvious, weigh it. You’ll need to make a new video to do this. You should have something visible around your waist (e.g. a belt), because you will need to watch the up and down movement of this. And around the belt, there should be an object or pattern on your shirt that is also visible and at least 10 cm long. Take a frame of the belt at the highest point on your waist and one at the lowest point. Correlate the difference to the 10 cm mark. If the difference is greater than 10 cm, you need to address this.
How can you change the vertical oscillation?
During running, stride rate, stride length and vertical oscillation (stride height), a triumvirate of members that are symbiotic with each other, each have an effect on each. If you have a low stride rate, you may be striding too long or too high. If your stride length is too high, you may be stepping too little or too low, if your stride height is too high (vertical oscillation) you may be stepping too little or too short. In other words, if you want to improve one value, you can (also) do so by changing the other two values.
To demonstrate my previous statement, I went for a run and increased the number of steps per kilometre. It is very important that I ran at the same speed all the time and ran on flat terrain all the time, so that there are no other factors that could affect the step rate, step length, step height (vertical oscillation) triumvirate. The goal was to run the first km at 150, the second at 160, the third at 170 and the fourth at 180 at the same pace. That’s what I did:
Unfortunately, I didn’t manage to run the 150 stride, but it’s quite clear that if I increase the stride, the stride height decreases nicely, and although this wasn’t the goal, the stride length decreases (because the speed didn’t change). At 161 strides, I still have 11.5 cm of vertical oscillation, which is above the normal range, but at 178 strides, I have only 9.2 cm of vertical oscillation, which is in the good zone
I’ve written a previous post about pedometer and its importance. It’s worth a read as well, because as well as helping you to set your optimum stride height, it can help you with a number of other things.
What else does stride height, stride length and stride count affect?
Or we could say what else they interact with, because they influence each other back and forth.
Fortunately, the Coros Pod can measure not only the above mentioned running dynamics, but also other important numbers:
Pace ratio
This is the ratio of step height to step length. The lower this ratio, the more efficient the run. In other words, the lower the stride, the longer the stride, the lower the stride rate. World champion marathoner Eliud Kipchoge, for example, had a stride length of 188 cm when he ran the two-hour marathon, if his vertical oscillation was between 8-9 cm, his stride rate was 4%. He managed to do all this with a height of 167 cm, and of these 188 cm strides, he did 187-190 per minute.
Tracking time
Ground touch time is the interval of time it takes to roll over, i.e. the time between touching the ground and leaving it. The shorter this time, the more time you can spend in the air moving forward, so you can run faster. The ground touch time for elite runners is under 180 ms, for an amateur runner under 270 ms is good. The ground contact time (GTC) tells you something else. It is not difficult to see that if you arrive on your heel and kick off your toe, you need time to roll over, but if you arrive on your toe, you need much less time on the ground.
Right/left ratio
The right/left balance (l/r balance or GCT balance) shows the difference in ground contact time between the right and left foot. The normal ratio is between 50-50.5 for either side. I spend 0.3% more time on the ground with my left foot, but it’s still within the normal range. If someone is not in the normal range, i.e. running sideways, they are more likely to get injured, but also get tired sooner. Even though we are talking about the legs, our arm movements have a big impact on this (too). Observe your arm movements while running. The more they move forwards backwards the better. If you are “mowing” your arms in front of your body, i.e. moving your arms to the right or left, it will twist your whole body and most likely to one side more than the other, it is worth paying attention to this too
In the world of modern carbon disc running shoes, you may need to re-evaluate the ideal vertical oscillation value?
A few years ago, carbon plate running shoes burst onto the market. The plate with the resilient foam underneath and above it basically acts as a spring, meaning these shoes are much more bouncy. The question arises as to whether the vertical oscillation should be kept between 5 and 10 cm.
On the one hand, all the above running dynamics indicators should be approached holistically. If only one is out of the normal range, there may not be a problem. In addition, they interact, so if all indicators are good, just a slightly higher vertical oscillation due to a shoe with a carbon sole is not necessarily a problem (but may need to be corrected).
To be fair, most carbon plate shoes are for fast running (averaging faster than 4:30km) and only fast running will give you that bouncy, springy feeling. At that pace, there is a serious step increase for sure and it’s hard to do big jumps at a high cadence.
Of course, the technology continues to evolve, and at the time of writing this post, several manufacturers are no longer putting straight, smooth carbon discs in their top shoes, but S-shaped ones that throw the runner forward rather than up. Such is the case with Saucony’s Speedroll technology, which they use in their Endorphin shoes.
So back to the question, with proper running technique, you can maintain 5-10 cm of vertical oscillation in carbon plate shoes. But if Eliud Kipchoge, who runs at the 188 cm average stride mentioned in the post, needed a vertical oscillation higher than 10 cm for that 188 cm stride length, I think we would forgive him…
