Why does it seem like you can jump higher while moving than standing? When you’re standing, you use all your muscles for one big lifting motion to push yourself straight up. It seems like with most of your energy devoted to going in one direction, you should be able to jump far higher than if you get a moving start. When you move and jump, some of that energy is directed to the side and lost, so you shouldn’t go as high, but it seems like you do. Why is that?
I imagine that it is to do with the structures of the legs storing and then releasing some of the that kinetic energy from the forward motion.
The experts include the track stars who are the best high jumpers. If they are correct, and I believe they are, then it is because of the kinetic energy generated by the running and then at the point of jumping, their swinging of the non-jumping leg and the arms while launching off of one leg.
High jumpers translate that lateral kinetic energy into the vertical jumping force they generate, and it is a greater total force than if they jumped from both legs while standing still.
The standing vertical leap record is a bit over 5 feet, around 63 inches as I recall. And that is phenomenal to watch. He does have a bit of forward motion, because he leaps onto a platform for the record. So it is a combination of an astonishing vertical leap, plus long legs that they can tuck upward.
The more common vertical leap we used to try was measured by standing next to a wall and leaping, then slapping the wall to make a mark as high as you could reach. We used chalk or a marker. Compare that to your resting fingertip height to get the amount you leaped. It isn’t very much for the average person, 18" or so.
The high jump record is over 8 feet. To achieve this the jumper certainly needs a high initial jump, but then must be athletic enough to rotate the body around its center of mass. So his legs must still be accelerating from the initial leap so they can carry over his body.
I was a pole vaulter of sorts. Mainly because our high school’s best vaulters were also the best in other running events and coach didn’t want to risk them. But that points out the main thing, you have to be fast to clear that bar.
Watch this video of the famous Dick Fosbury doing the Fosbury Flop (developed later, we never tried it, we used the standard Western roll).
He sprints as fast as he can, then at the last step he actually begins turning sideways to pivot off his jumping leg, just like a pole vaulter pivots off the pole.
DennisWhile each individual part of the body must clear an 8-foot bar, you don’t need to have all of your body simultaneously 8 feet above the ground. The trick of the “Fosbury flop” is that your center of mass need not ever get as high as the bar; proper distribution of your body nonetheless enables each part of your body to snake over the top of the bar.
Perhaps there ought to be a different high jump sport in which the contest is to get your center of mass as high off of the ground as possible.
How would you measure that, though, in practice?
Former Fosbury flopper here. Mixdenny said it best. Your run-up is circular and you are leaning away from the bar when you jump so that centripetal force is redirected upward off your jumping leg as if it were a pole vaulter’s pole. Done properly and with enough speed you will go way higher than if you are just standing there and using both legs to jump straight up (also, it is illegal to high jump off of 2 feet).
This is actually the entire answer to the OP in ten words. The reason running allows you to go higher is it allows you to build kinetic energy that can be redirected upward.
Why?
I never understood that myself. But I did mess up more than a few times in my early years and was fouted for it everytime.
I was about to ask the same question about the one-footed take off but a quick google and I found this thread
The explanation that I was given a long time ago was that there used to be two events, the running high jump and the standing high jump, with the requirement for the former being that you had to take off from only one foot. The assumption was that taking off from two would be an advantage.
However as it turns out the running high jump off one foot permitted higher jumps so the restriction on jumping from two feet is pointless, but it has historically remained anyway.
Bertie Wooster (of Jeeves and Wooster fame) often would set records for the sitting high jump when informed of something particularly frightening.
Seems like a victimless crime to me.
This Chinese video (per the translation) shows an acrobat clearing 3,12 metres with a two-footed take off (the world record is 2.45 metres).
http://video.sina.com.cn/p/news/s/v/2009-11-06/095060427128.html
Not a running take off as such, but that’s pretty impressive.
I was going to mention the circus. We went to the one in Cleveland a year ago (not sure which one it was). They did pretty much the same thing, kept adding rings to the height, and their best jumper would somersault through it. It was amazingly high.
A few things I noted: They jumped off a pad, probably only about 3-4 inches thick but I assumed it was spring assisted somehow. And they did jump from two feet after a fairly high last hop.
Dennis
I think the Chinese discovered Flubber.
This question brought to mind my own question.
Watching the acrobatic floor gymnasts, I wondered about the height and distance they were achieving during their routines. Compared to the high and long jumpers. They seem to be hitting great height and distances, with the added difficulty of remaining upright and set to continue with more feats.
Removing the rule against a two footed takeoff. Could a somersaulting gymnast be going higher than a high jumper at some point? Seems airborne distance isn’t as important to them. But still can be impressive.
Its kind of been said, but I’m (ha-ha) jumping in as a former high-jumper (Western roll) - yes the planted leg acts much like a pole-vault pole if you do it right. Additionally part of the mechanical advantage is to get your other leg and foot as high off the ground (i.e. raised center of gravity) before the planted foot leaves the ground.
I could only do a bit over 6 feet and always felt the event should be renamed the ‘medium jump’ so people wouldn’t expect so much.
I once witnessed a one-legged high jump competition. They hop, hop, hopped up the barrier and then jumped. Clearly, they were still turning forward momentum into height.