Hills

I've noticed a lot of questions about how to run up hill, how to run downhill, and whether or not to have a heel strike or a midfoot strike or a forefoot strike during each. Here's my idea on the matter. It works for me and maybe it will work for you too.  

 

 

 

 In this picture, the stick figure has a line traveling through the pelvis. That line is parallel to the ground and perpendicular to the lumbar.

 

 

 

 

This next stick figure has all the same features - pelvic line parallel to the ground and perpendicular to the lumbar  - but it is running up hill. This runner is using his abdominals to hold a "crunch" position

Finally, the downhill runner has all the same features again -pelvic line parallel to the ground and perpendicular to the lumbar - but it's running downhill. This runner is using his back muscles (erector spinae and psoas) to hold a squat-like position on each step.






What makes this work is that all the other features of running stay the same. For example, to maintain a constant speed, become fully weight-bearing with the foot directly under the body. While running up hill there is less time spent in the air so you might need to have a faster stride to bring the foot back under the body by the time it is fully weight-bearing. With downhill running there is extra air time so you might need a slower stride so that being fully weight-bearing happens directly under the body and not behind it. 

Some Math

So I was doing some thinking about the cheetah and what makes them so fast and I was reminded about the old formula for running speed, stride length x stride frequency. The Cheetah, according to a video from an earlier post, has a stride length of about 23 feet. So how many times a minute does 23 feet pass by when you're moving at 78mph? What is the cheetah's stride frequency?

78mph x 5280 feet per mile / 60 minutes per hour = 6864 feet per minute

6864 feet per minute / 23 feet per stride = 298 strides per minute

298 strides per minute! Compare this to a human being running at top speed. The two top guys right now are Usain Bolt and Tyson Gay. Tyson has a step length at top speed of about 8 feet or 2.5 meters. Bolt is a little longer but not much. That means a stride (left right sequence) is about 16 feet for the top human sprinter.

28 mph x 5280 feet per mile / 60 minutes per hour = 2464 feet per minute

2464 feet per minute / 16 feet per stride = 154 strides per minute


The top human sprinter goes through a "left/right" sequene at about half the speed as the cheetah goes through the "front/back" sequence. If we could hit 298 strides per minute, even if the stride length didn't change a bit (which it would; it would get longer), man's top speed would become 54mph.
Now, if you know me, you know I'm not into saying things can't be done. Rather I ask, "How can things be done." After all, cheetah's and humans are both "red meat." The muscles of both species are limited by certain physical laws such as ion exchange of calcium and potassium. Both are under the same atmospheric pressure, both are made up of actin and myocin which make up the crossbridges of the muscle fiber. So what makes their fast twitch muscle fibers capable of contractions nearly twice the speed of ours?
I will need to look into this answer more, but I believe the answer is "their muscles are NOT faster than ours." Which begs the question, then "how is their cadence nearly twice as fast?"

To answer that question, I went to a website that explained the physics of a 7 foot bullwhip. I noticed that cheetahs begin their movement at their head, not their hips, and a wave is initiated that travels down the spine to the legs. I also noticed that cheetahs have very big necks, tapering waistlines, and very skinny legs. Keep those two facts in mind as you read about the physics of the bullwhip.

"The whip’s pop is a result of the tip of the whip (the “popper”) moving beyond the speed of sound and creating a vacuum in space. The air rushing back into the vacuum makes the pop sound. A whip generates its speed through the “conservation of energy”. The body of the whip is built to be a continually shrinking diameter from the thick handle down to the tip of the popper which is only a few strands of fiber. A little energy imparted at the handle accelerates along the diminishing diameter until the popper is moving over 700 miles/hour." http://bullwhip.org/?page_id=17

So a very slow movement at the wrist, perhaps less than 10 mph, turns into over 700mph at the tip of the whip. Let me remind you that whips have no fast twitch muscle in them. In fact, they have no muscle at all. So how does it travel over 700mph? "The conservation of energy" through "a continually shrinking diameter" causes "a little energy" to "accelerate"
Try grabbing the middle of a whip and getting the end to move 700mph. Your hand will have to move 200mph. But if you grab the handle, you can gently move it a meager 10mph to get the speed at the end. Cheetahs are designed that way too. Big at the origin of power (the neck and shoulders) small at the place that needs to be fast (the legs). Now here's the good news. People are also designed that way. Big up top, with a continually diminishing diameter.

Here's my theory: I think running from the hips is like trying to use a whip holding it from the middle. Much higher performance is needed to achieve the same results. By using muscles farther from the feet in an area with a larger diameter in the torso, a lower contractile speed will be necessary to achieve the same speed in the feet. And perhaps the same contractile speed will yield a much higher speed in the feet. Perhaps this method will help us to raise our pathetic 154 strides per minute to something closer to the cheetah's 298. We may never reach a full 298 strides per minute in the 100m dash because our bodies do not taper off to the degree that the cheetah's body does, from its massive neck to its toothpick legs. But we can certainly achieve a higher cadence than we do right now.