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.

Conclusion on Arms

As I said before there are 8 different combinations. But there are also an infinite number of degrees to which each can be done. Here is a compilation of how each one effects running.

1. Timing - Leading with the arms speeds stride rate, causes the foot to land farther underneath the body and leave the ground faster.

Timing ahead of legs = fast stride rate
Timing with legs = neutral stride rate
Timing behind legs = slow stride rate

2. Arm length - A greater difference in arm length causes a greater bend in the torso which adds power and extends the stride length.

Arms longer moving backward = longer stride length
Arms same both directions = neutral stride length
Arms longer moving forward = shorter stride length

3. Arm angle - A greater inward angle in the arm swing towards the body's center line has a twisting impact on the torso when the timing leads the leg cycle, but it has no impact when it is in a neutral timing or lagging behind the leg cycle.

Arms swinging inward = no impact unless the armswing leads the leg cycle. If arms lead leg cycle, it adds power(force) but impeeds speed via range of motion. Great for up-hills or pulling a weighted sled.
Arms swinging straight = does not add power, but does not impeed speed either. Legs move freely. Great for down hill running, flat traeadmill running (no wind resistance), and running with a back-wind.

I believe if these three elements can be understood for what they do independently of one another, then the best combinations can be used for various running conditions. For example, to increase stride rate and stride length and transferring power through the legs from the torso, (1) lead with the arms (2) while lengthening the arm length on the back swing and (3) swinging the arms halfway between parallel to running direction and across the body. Stride rate comes from 1, stride length comes from 2, and the power to sustain that form at higher speeds comes from 3.

Alternative Arm Swing 2

In the last two entries we've covered changing the timing of the armswing in relation to the legs, and changing the arm length in the backswing compared to the arm length on the front swing. This entry will cover the swing angle.

Most runners are told "Move your arms straight forward and backward parallel to the direction in which you are running." No explaination of why, or how this is beneficial, so in this final entry on arm swings, let's talk about my two favorite questions. "What does it do" and "When would I want that to happen?"

Go for a run and swing the arms straight forward and backward as recommended. Then begin to swing them inward toward the center line of your body. How is this changing your running form?
Try it while leading with your arms (like discussed in the first article on arms) and do it while changing arm length (like discussed in the second article on arms) and do it while both leading and changing the arm length. What does it do?

I've noticed that when I lead with the timing of my arms and begin to cross my body slightly with my armswing I experience a twisting motion in my torso along the transverse obliques. When I move my arms back to moving parallel to the direction I'm running (just straight forward and backward) this twisting goes away. So, when would I want to use this?

Apparently, according to my experience, leading with the timing of the arms while swinging the arms across the body and causing the torso to twist at the transverse obliques has a significant impact on uphill running. This includes stairs as well.

Go out an experiment with combinations of the three elements of the armswing.
1. Timing with the legs (leading, following, or at the same time)
2. Lengthening the arm on the backswing and shortening it on the front swing
3. Swinging them forward and backward or at an angle towards the center of the body.

This makes 8 different possible combinations of arm swings in relation to th legs and they all work best under slightly different circumstances.

Alternative Arm Swings

We just talked about changing the timing of the armswing in relation to the leg cycle. But what about changing the arm length, or even the muscles used to initiate the arm cycle?

When a cheetah runs (granted, it's front legs touch the ground and ours do not), their front legs are straighter when they are moving backwards, and they are tucked under the body when they are moving forwards. So I tried this with my arms.

As one arm straightens out and moves backwards, the center of mass of that arm moves farther from my shoulder joint. At the same time, the opposite arm is shortening and moving forward which causes its center of mass to moce closer to my shoulder joint. What does this do?

First of all, I notice that my body is forced to bend laterally at the thoracic spine like a side crunch. It leans towards the side of my body with the shorter arm, and away from the side of my body with the longer arm. What does this side-crunch of my body do?

This side-crunch of my body has an impact on my legs. Basically, when I'm airborne, moving my upper body left and down causes my lower body (including my legs) to move left and up. Since it is the left leg that will be touching the ground next, this actually improves my air-time and slows down my stride rate. When would I want this to happen?

As mentioned in the last entry, improved air-time and a slowed stried rate is associated with downhill running.

Conclusion:
So, if changing the length of each arm causes my torso to bend side to side and is good for downhill running, might I conclude that the best strategy for uphill running is to do the opposite? To have both arms with a very similar bend in the elbows? And what about flat running? Perhaps an intermediate amount of lengthening and shortening with the back and front swing.
Try this and experiment. See how it works.

The Arm Swing

So, if you've been reading my posts, I try not to say what is right and wrong when it comes to running. In fact, thats my whole philosophy on life. Instead, I ask questions like, "What does it do?" and "When would I want that to happen?" And the armswing on running is no different.

Most runners will time the arms and legs together. In other words, left leg goes back, right arm goes back. Left leg stops, right arm stops. Left leg begins moving forward, arm begins moving forward. They begin and end movement at the same time. So, what happens if you change that?

If the arm swing begins slightly before the front foot lands, instead of simultaneous with it as is popular, I've noticed two things. First of all, since the arm swing begins while my whole body is airborne, that small transfer of mass in my upper body actually affects my legs by bringing my landing foot more underneath my body, and my trail foot less behind my body. This actually gets me into the acceleration position as described in the entries on the legs previously. So when would I use this offset timing in the armswing?
1. When I'm running uphill
2. When I want to accelerate

After this finding, I tried the opposite by letting the timing of my armswing initiate a split second after my front foot lands. This backward offset timing caused my foot to land farther in front of my body with my trail leg staying farther behind, and had an overall slowing effect. But it had another effect too. It increased my hang time in the air. So, when would I use this reverse offset timing in the armswing?
1. When I'm running downhill and trying to maintain speed
2. When I want to decelerate after a race or an interval.

The next entry will include more information on different types of armswings.