More efficient running style
183 watchers
Mar 2018
11:00am, 19 Mar 2018
1,834 posts
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Canute
When starting from rest, we lean forwards and push back against the ground (or the blocks if you are a sprinter). Once we are moving a constant velocity the only forward directed horizontal force required to maintain that velocity is the force required to overcome air resistance and the braking that arises when the CoM is behind the effective point of ground contact, in early stance phase. When CoM is in front of the point of contact in late stance, the line of push exerted via our stance leg has a backward directed component that produces an opposite (forward directed) ground reaction. Contraction of the extensor muscles, assisted by elastic recoil, contributes to that push. |
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Mar 2018
11:28am, 19 Mar 2018
1,835 posts
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Canute
With regard to the 'extensor paradox' I believe that is largely a misperception arising from over emphasis on the role of the quads in achieving the triple extension at hip, knee and ankle that provides the push in late stance. The electromyographic data indicates that the quads do not contract strongly after mid-stance. However, this is only presents a paradox if you do not take into account the powerful action of the glutes. The calf muscles also contribute. And elastic recoil should not be neglected.
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Mar 2018
1:08pm, 19 Mar 2018
28,469 posts
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HappyG(rrr)
Much politer discussion than 8-10 years ago, but actually, exactly the same content!  Still fun to read though. For the runner, we just need to know what drills to perform to improve our pace and/or reduce our injury proneness. I guess a coach, or someone developing a new approach, needs understand the actual mechanics and to not misrepresent the basic physics. As a runner, I find thinking about "pelvis first, chest up, head up, high cadence/short stride, and light foot fall" useful. By which I mean for me, this translates to faster running with less injury. I believe most of those characteristics are common to Pose, Stride Mechanics, Chi Running and many other schools of running form. I can't do all of them, all of the time, but practicing some of them at certain times (either drills, or just concentrating on one or other during an easy, normal run) means that it all comes together reasonably well when I need it, in a race or longer or quicker run. G
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Mar 2018
1:15pm, 19 Mar 2018
325 posts
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SSLHP (Shoes smell like horse piss)
'Lean forward' - from the shoulders, nothing happens, so I guess you mean displace one's body weight...or CoM...or unbalance forwards, or fall forwards, perhaps? What is it that moves our CoM to the position of late stance phase ready for the push as you describe it? Can't be momentum as that's deceleration and more importantly, it's not a force. As I understand it, the hGRF to which you refer is always below body weight and therefore insufficient for forward propulsion. Active pushing only sends you up, higher. If I run in place, then push hard into the ground with every step, even at a high cadence I still don't go anywhere. What am I missing? I even tried leaning forward with my head and shoulders. Nothing -I'm still running in place. What do I have to do to move forwards? |
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Mar 2018
1:20pm, 19 Mar 2018
326 posts
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SSLHP (Shoes smell like horse piss)
HappyG I think what you said is true. At the end of the day it's about perception, or more importantly it's about our body weight perception and how we apply it efficiently. I think your personal cues are excellent. Interesting no 'push' or 'push hard'
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Mar 2018
1:50pm, 19 Mar 2018
28,470 posts
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HappyG(rrr)
SSLHP - lean forward (in all the texts I have read) is "from ankles" (a weird description). In practice that means "lead with pelvis" one of my first cues in my list. Jog on spot, light, with high cadence, then lead with pelvis. You will be moving forward. Of course, that means you are applying a backwards force, but you don't know you are. All you know is that you have moved your pelvis forward and Lo! you are running! G
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Mar 2018
1:51pm, 19 Mar 2018
327 posts
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SSLHP (Shoes smell like horse piss)
I believe muscles are used to protect, steer, balance and support. Not for propulsion. Actively pushing is not a requirement to move ourselves forward, but falling out of balance is. And body weight, balance, falling etc only have meaning because of gravity. We should always keep these discussions polite -we're all wanting to learn and everyone's opinion should be respected |
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Mar 2018
1:58pm, 19 Mar 2018
328 posts
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SSLHP (Shoes smell like horse piss)
HappyG I have a thing about the cue 'lean' I created this graphic to help runners understand why drive.google.com |
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Mar 2018
1:58pm, 19 Mar 2018
28,471 posts
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HappyG(rrr)
Try scrolling back to 2009/10. Some of the characters in the most heated discussions are no longer in Fetch. That tells its own story! The process of catching yourself while falling to the ground, if it is to result in you moving forward, not stopping (in balance) or slowing down (still in balance) requires you to be applying at least some part of the force, backwards. That's just physics. However, minimizing the braking effect, so minimizing the backwards force required to overcome it, plus minimizing the upward propulsion (hence minimizing the total loading during that backward force) result from all the above cues. But you are still pushing back to go forwards. Just not consciously so! G
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Mar 2018
1:59pm, 19 Mar 2018
28,472 posts
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HappyG(rrr)
Ah, you can't. This one was only started in 2013. Shame. Sort of! G
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