Up/down movement when running is not what it looks like

[@karinaniskanen1386]

Thank you very much for complicating things! 😄

[@yenge5434]

Being a physics nerd, I love Frederik's videos! Thank you. I just wish he added one more point here: how much the center of mass moves basically 100% depends on air-time between steps, which is pretty much controlled by cadence. It's laws of physics if you spend 1 second mid-air your center of mass is going to move that much. High cadence reduces air time between steps because steps are shorter

[@xMithras]

I would argue that air-time + contact time determine cadence. That being said, a smart algorithm can probably accurately measure all of those based on HRM acceleration, given that landing and push off are not 100% smooth. And therefore can also be accurate about actual center of mass movement / vertical oscillation.

[@nikitaw1982]

@@xMithraslumoRun looked great. Never got one. Wearable sensor u put on ur tail bone.

[@herbertbay]

Love your videos, thanks so much. Very insightful. I would wish for some instructions on how to reduce oscillation of the center of gravity. What to do to improve my running with less oscillation.

[@CSRunner7]

Thanks for this. So much un researched nonsense put out on social media by running influencers!

[@prentishancockgardening]

Another great video Fredrik. I agree with you on this one.

[@lornadoell]

Thanks for the videos. I'm learning a lot. I can usually understand the theory, but find it harder to translate it into correct movement. Your teaching style seems to suit my brain, and body. Thanks again.

[@kjlkathandjohn6061]

Lowest down position happens at the conclusion of shock absorption with ankle, knee, and hip joints. Here "leg length" is in a collapsed state, with these three joints flexed. As grounded foot and leg pass to rearward, the three joints become straightened, thus lengthening the leg and with sufficient recoil to lift the falling torso up again and forward before it is retracted from ground position. Jointed leg length changes while foot is on the ground.

[@mindfulmomentswithColm]

since not much instruction given on how I have a couple ideas: focus on timing so head over toe then switch from glute/hip & quad push off, when "pushing off" too much with knee also done in stair climing and standing up, excessive (up/down) force gets utilised. the david weck method is also helpful, to figure 8 the shoulders (back) and connect the lats and coil the side abs, bringing shoulder to hip on one side then the other. while keeping the arch of foot strong and not allowing knee/ankle to collapse in (a common habit) when runners have hands in front it seems to coil/uncoil like yin/yang in tai qi one hand pushes the other pulls. try to wear barefoot shoes or none and this will strengthen the arch and land outer edge (where naturally the foot touches earth first)

[@jonb9194]

It's about finding the right combination of ground time and air time to match the strengths of each runner, and adjusting the amount of "lope" during ground contact (stance phase). Every runner follows the same ballistic trajectory during the flight phase, regardless of weight.

[@IainThacker]

Hej, Fedrik! With your ability to measure CoM movement with your equipment, have you tried to see how accurate consumer devices are at estimating vertical oscillation? Even if they're accurate, I suspect that most of us haven't got a clue what would be a "good" vertical movement or, probably more useful, ratio.

[@suehirogaribright]

I'm also curious how good/badly correlated the oscillation measured by those straps and the real figure

[@liamroche1473]

The only thing I can be pretty sure of is that the centre of mass moves in close to a parabola when there is not a foot on the ground. That does not even determine the height the centre of mass rises (because there is no guarantee the high point of the flight is exactly in the middle of flight time. Oh, also we can be sure that the average vertical speed is zero on the flat.

[@thibod07]

This is hilarious! I Never though of those aspects of running! I cannot really argue about it’s veracity! I am not that smart! My question is how can I benefit from that knowledge when I run?

[@Yurkevich22]

great explanation but what about any actionable tips on what we should be doing to reduce the center of mass movement?

[@paulnorman8274]

To reduce COM amplitude, increase cadence. A bouncing ball is a decent enough model: The bounce cadence is faster, when it bounces less high. You probably can deviate from that with some strange contortions during ground contact time, but in general, the bouncing ball model of running is not too far off.

[@Raucherbeinknacker]

Does the center of mass have automatic doors and escalators and stuff?

[@martinrosschou]

Is there a way to try and "feel" how much I'm moving my center of mass? Like clear sign that it is moving up and down to much for example

[@henri-5606]

And sooooooo *what* should we do then please Fredrik?

[@Raucherbeinknacker]

I just think about how two hamburgers wobbling up and down affect the center of mass😂

[@TheWolfAkella]

🙏🏽

[@shelbyatracing]

Therefore STRYD exists, and calculates many more parameters with precision. Have just taken a look, on today's easy run STRYD - 8,51 cm of vert osc., Garmin hrm-pro 9,4 cm. Last Marathon race STRYD 8,37cm, Hrm-pro 7,9 cm.

[@reeltaiwan]

But how does a footpod know where your center of gravity is? At least the HRM PRO is closer to your center of gravity than your foot ;-)

[@shelbyatracing]

@@reeltaiwan We should look at center of mass not center of gravity (it is not exactly the same). Stryd calculations were validated with high resolution motion capture systems, dual force plate treadmill, and metabolic testing. More than that, Stryd singles out vertical work rate done (in place) - power required to displace the center of mass vertically without considering forward movement. HRM Pro is reported to produce much "noisier" data as opposed to Stryd exactly because it is far from foot. And one interesting thing - some studies show that low vertical oscillations are correlated with better running economy (lower metabolic cost) while some studies show the exact opposite (higher metabolic cost).

[@reeltaiwan]

@@shelbyatracing I'm putting more weight (mass?) on your last assertion than on the validation part. I can see that if the Stryd user provides details on his/her weight/height/limb/torso/abdomen measurements, etc., then algorithms could do a good job of estimating vertical oscillation...But at the end of the day, I don't put much faith in vertical oscillation, partly because I'd think it was job done if I look at my HRM-Pro stats (6% oscillation when I'm easy shuffling and

[@itzzitzz]

Hilarious sense of humour 😂

[@michaelanthony679]

So happy I wasted my time, I always wanted to know how basketball players jumped….