On the need for easy, slow, relaxed exercise

Posted on April 20, 2015


This is partially a continuance of my notes on the book Kinetic Control: The Management of Uncontrolled Movement. The rest of my notes can be found hereThis is part 5, but drifts away from the book a decent amount. While this post is about slow exercise, I also delve into injury rates in contemporary sports, where humans move as fast as they possible can.

The muscular view

When discussing the muscular roles of stabilizer versus mobilizer [from Kinetic Control]:

“Some muscles are more efficient at one of these roles and less efficient in the other role. For example: latissimus dorsi is a powerful multi-joint medial rotator of the shoulder to accelerate the arm in the sagittal plane during throwing activities. Latissimus dorsi is biomechanically suited to large range, high speed, high force movement at the shoulder.”

Latissmus Dorsi; left and right.

Latissmus Dorsi; left and right.

The authors contrast the lats with subscapularis, whose role is more to prevent the humeral head from excessive translation. One is more generating movement, the lats. The other is more preventing movement, the subscapularis. (Note how more is italicized. This is a continuum the authors are describing, not a definitive role.)

Subscapularis exercises


What the authors are getting at is you tend to see an imbalance between these mobilizers and stabilizers in movement issues. The lats (mobilizer) tend to get way too active, the subscapularis (stabilizer) way too inactive, in those with shoulder issues, for instance.

By training heavily or speedily, you make it more certain types of muscles, like the lats, will be firing on all cylinders…which you often don’t want in someone with movement dysfunction. The lats are so big, they’re conducive to large range of motion, fast / heavy movements. But you want the lats to start to calm down, and these other guys, like the subscap, to wake up some. The faster you move, the more intense the lifting, the harder this is.

This is one way of looking at it, and in a lot scenarios, makes sense. I tend to prefer another way though.

The nervous system view

Rather than attempt to classify latissimus dorsi and subscapularis in this manner, I prefer to say, “This person has acquired the habit of using their lats more than their subscap.” More broadly, “This person has acquired the habit of moving in this particular way. Oh, and that’s likely caused the lats to work too much and the subscap not enough.”

One reason I go with this is because even in some very light, easy activity, you’ll see people use their lats too much. You don’t need to be throwing a baseball for this to happen. You can be rotating your arm with no weight, at whatever speed.

While hard exercise guarantees a certain involvement of the lats; easier exercise does not guarantee lesser involvement. It helps lead us there, but it’s not guaranteed. The only guarantee of moving a certain way is to move a certain way.

For the client, this is more intuitive than the muscular perspective. As soon as you start dropping anatomical terms, unless the person knows some solid anatomy (rare), you risk eyes glossing over. On the other hand, we all get that the more intensely you do something, the more likely you are to revert to old habits. To do something you’ve been doing for a long time, but in a different way, requires one to slow down, and perhaps regress things for a while. AND concentrated effort. You don’t slow down and suddenly move the way you want. We don’t need a scientific explanation for this; we get it. But there is a more scientific reason as well.

A great book called The Power of Habit details the role the basal ganglia plays with habit. It appears that’s where we store habits. It’s where more of our primitive, non-conscious, activities come from. Preventing your jaw from always being open, breathing, swallowing. Activities where you’re generating movement, but don’t typically realize it.

From Wikipedia.

From Wikipedia.

As you get further away from the basal ganglia, as you get further away from the lower-middle of the brain, more complicated thinking takes place. As the basal ganglia takes over for an activity, like running through a maze you’ve eventually become familiar with, less overall brain activity takes place. As other structures besides the basal ganglia contribute, like when running through the maze for the first time, more brain activity occurs. As something becomes more habit like => less brain activity. Breaking that habit, doing something new, doing something for the first time => more brain activity.

-> It’s fitting to comment here one of the things I constantly have to tell people is to slow down (a lot) and think more about how they’re moving. The reason this is so tough for people is because I’m asking people to expend more energy to do (pretty much) the same movement. That’s about as antithetical to human survival as you’re going to get.

It’s a reason changing people’s behavior is so hard. Habits save energy; breaking them requires more effort than usual. People hate expending more energy than needed.

This is also where the pain science and movement science worlds don’t realize they’re often saying the same thing. Asking someone to move differently is training the musculoskeletal and the nervous systems. Changing how you say, move your arm, changing that habit, is training the brain.

The other way I think you can look at this is the more thought that goes into something, the higher up in the central nervous system the processing happens. By higher up I mean literally further from the ground. The basal ganglia is closer to the arms than say, the frontal lobe.

As things become more of a habit, more like a reflex, this higher level processing isn’t needed like it was. This is so we can process the movement even quicker. The signal literally has less distance to travel. Many of us are aware of this with the reflex tests done during a routine physical exam. Instead of going all the way up to the brain, a nerve signal can make it only to the spinal cord and get the job done. A doctor taps your knee and you don’t consciously extend it, but it extends. Reflex versus conscious thought.

Meaning the faster you try to do an exercise -the more you say “we need to do this movement with less processing”- the more likely you are to revert back to a reflexive pattern. The one you may be trying to get rid of!

This applies to heavy lifting as well. Even though a heavy lift may be executed slowly, that doesn’t mean the nerve signals aren’t firing as fast as they can. Nobody is actually trying to lift a maximal squat slowly. It’s the weight is so heavy that’s as fast as the person can move. Besides, have you ever tried to do a bunch of thinking under maximal effort? It’s tough to think about more than “I need to get this damn weight up, NOW.” Hence, the heavier people go, the more likely they revert back to a reflexive pattern (old habits).

Plus, when trying to get other muscles involved, the brain often isn’t as good at getting those muscles to fire. It hasn’t had the practice. But it’s very good at getting other things to fire, like the lats versus the subscap. The heavier you go, the more likely the body will revert to what it does best. Survival takes precedent. It’s better to put that energy into lifting the weight than it is to use it for thinking “how am I lifting this weight?”

You can only process so much, or expend so much energy, at one time. That’s where habits and reflexes help share the workload. Imagine if you had to think about every single thing you did everyday. Habits can be marvelous things…but sometimes those habits and reflexes need to be changed. Which requires thoughtful, slower, relaxed, motion.

The physics view

I’m currently enrolled in a course on aerospace engineering and human spaceflight. (I’ll be writing about why eventually.) I came across an equation which I’ve seen before, but suddenly realized had some application to human movement I hadn’t thought of.

Drag Equation

From Wikipedia.


For those math averse, I promise this will have a basic, clear takeaway. For those who were always in the back of the math class, who got tired of raising their hand, “Why am I learning this?” I’m going to give you a why!

Drag is the resistance we feel when we move through a fluid. Let’s think about someone running. Our fluid would be air in that case. (Gasses are fluids, if you didn’t know.) We feel the air, “wind,” as we run through it.

Because we’re talking about the same person each time, the drag coefficient of the person will be the same. We’re not changing our skin -it’s not becoming more rough for instance- our body isn’t going to change shape, and the area of the object (us) moving through space will be constant. Of course, this could change over time. Such as gaining weight. But we’re talking about the same day here.

That simplifies things to what happens to be a different variable:

Dynamic pressure is the pressure of the fluid acting on the structure passing through it. In rockets this can get complicated because as you go higher, the air gets less dense. Initially though, the velocity of a rocket will increase faster than the air density decreases. All the way to this point of “Max Q.”

Max Q is at 60 seconds in this graph. Credit: http://media.tumblr.com/tumblr_m2j49btb0B1qbnrqd.jpg

After Max Q, air density decreases so quickly that dynamic pressure also decreases. Notice the graph come tumbling down after 60 seconds.

In a lecture I watched, the professor, who was an astronaut, mentioned how the NASA space shuttle would throttle down to roughly 70% of thrust capacity around Max Q. The idea is by going slower you lessen the dynamic pressure on the structure (space shuttle in this case). You increase the odds the structure will not collapse on itself. Max Q is where the structure’s integrity is most susceptible.

To be clear here, this is due to air. This isn’t like some foreign object the structure has to go through. The atmosphere, that thing we are always moving about, becomes this insanely hard object to get through.

With people though, this is all even simpler. Because we’re talking about going in a straight, horizontal not vertical, line, or at most jumping a few feet in the air, we can ignore air density. (It’s not going to change.) All we’re really left with variable wise is velocity. But what’s different about velocity compared to every other variable?

Drag Equation with exponent circled

That exponent is a huge deal. If you forgot or never learned, V * V = V^2. (Velocity squared.) All the variables matter, but how fast you go matters the most. This is why the best way to save on gas is to drive slower. You exponentially lessen the amount of drag the engine needs to overcome. Again, to go through air.

Going from 31.3 m/s (70 mph) to 29.1 m/s (65 mph):

  • 31.3^2 = 979.7N
  • 29.1^2 = 846.81N

Going 5 mph, 2 m/s, slower drops the force by 133N! Going ~7% slower causes a ~14% drop in the drag force.

But we’re not only handling the drag force, we’re looking to overcome it. That takes power,

Power to overcome drag formula


Fd is the force of drag. Fd * velocity = Power. Velocity is distance over time:

Fd * (distance / time) = Power

We’re interested in how quickly we generate force, not just how much we generate. Meaning velocity has become even more important. It’s now cubed rather than squared! You move faster through air and the force acting on you has gone up exponentially, meaning to go even faster you have to cube the power you generate.

The important takeaway

As you move faster, there is not a linear increase in extra force your body has to handle, or the extra power it has to produce. There is an exponential increase. For every little bit you move faster, your body has to handle a lot more, not a little more, force. It has to generate A LOT more, not a little more, power.

The athletic world is an obvious indication of this. Famed track coach Charlie Francis used to stop his athlete’s workout whenever they set a personal best. He intuitively understood the athlete just went to a point they not only have never been before, but even if they only beat say, a certain time by a tiny bit, often tenths to hundreths of a second in sprinters, their body withstood a lot more force. The body didn’t go a little beyond where it’s been, it went a lot beyond.

“At the highest levels of sport there is a quantum increase in CNS output for every increment of improvement …a 95% effort might require a recovery period of only 48 hours while a 100% effort might require up to 10 days”

The Charlie Francis Training System

Increase in 5% effort doesn’t cause an increase in 5% recovery. It causes an exponential increase in needed recovery. (Francis truly was a sharp as hell dude.)

The athletic world has more applications as well. The people who move the fastest need the most time off between competitions. Pitchers take five days rest between starts, and most pitchers will tell you they aren’t fully recovered in that timespan. (They get injured the most of all baseball positions for a reason.) A pitcher may throw, what, 150 pitches each start? Including warm-ups? The positional players may only throw maybe 100 times a day? But they’ll do that nearly everyday. Over 5 days a positional player may quintuple what a pitcher throws, but the lower speed gives them an exponential less amount of force they have to deal with.

Football players take an entire week between games, and they’re also never fully recovered. Compared to say basketball, which doesn’t reach the same speeds, where guys can play multiple times per week. (Of course violence is a big factor here too.) But even professional basketball players are trying harder and harder to get rid of back to back games, whereas teenagers will play everyday without problems. And yes, youth is a factor here too.

But think about kids versus adults. Kids don’t really tear tendons, pull muscles, or anything like that. Part of the reason here is because they can’t generate enough force / power. The speeds they deal with aren’t a threat.

Distance runners can train more often than sprinters. It’s tougher to recover from an all out 100 meter sprint than an all out mile run. (We’re talking high level athletes here, not beginners.)

You also see as people become more trained, they train less often intensity wise. They can’t go out everyday and train hard, like a beginner can. Charlie Francis’ system calls for two to three days of high intensity work, per week. If there is a race that week, then that counts as a high intensity day.

Bringing this back to corrective exercise, if you are, or are working with, someone and your form is on point, but you’re still having issues, going slower often helps. Sometimes it’s the difference between taking six seconds on an exercise -three seconds up and three seconds down, versus two -one second up and one second down.

Because now we know a difference of four seconds is more than four seconds to the body. A lot more.

Miscellaneous items

The paradox between the nervous system and physics perspective

I mentioned when slowing movement down you’re often asking a person’s brain to expend more energy based on the nervous system view. In the physics view, I mentioned going slower can be easier on the body. What’s the deal here?

First, the nervous system and the musculoskeletal system don’t always line up. Certain activities are more draining on the mind than the body, for instance. Going slower on a exercise, but trying to do it in a different manner, may require a lot more thought than lactic acid.

Second, as I’ll cover in a second, depending on how much you slow down, going slower can actually be tougher on the musculoskeletal system too. Although, the joints are often grateful.

Third, go fast enough and these two typically line up. Start running and you’re asking more of the nervous system and musculoskeletal. To where both will prefer slowing down.

Caveats and a technical point

Fluid dynamics, rocket science, nor humans are often so straight forward. I want to briefly mention the caveat of taking equations like air drag, at face value, too far.

If you have someone who has zero air flowing past them, like a treadmill versus outside, the treadmill will often feel harder. While air resistance is less, a person will usually feel / get hotter due to no air flowing past. I believe this was an issue in the endurance research for a while. Eventually somebody figured out putting a fan in front of a cycle test actually improved times.

Similarly, go too slow on a given exercise and eventually it becomes harder. We all know the training techniques where somebody tells you to go as slow as possible. It’s miserable.

This is actually true with Tesla’s vehicles (electric car maker), which is about as aerodynamic as automobiles get:

From one of Tesla’s blog posts on efficiency: http://www.teslamotors.com/blog/model-s-efficiency-and-range

Look at the range from 10-~20 mph. As you go faster, you actually use less battery power!

There is a threshold. Go too slow and you expend more energy than needed. Walking too slow is tougher than walking at a comfortable pace. There is an optimal level, and finally you get to a point where the faster you go, the more energy you need.

Lastly, I talked to my brother, a physics major, about all this. His first question, he hasn’t done a ton with drag yet, is if it’s correct to equate a human body and a rocket / jet. I think it’s worth addressing this. We talked some, and we’re pretty sure there isn’t any issue making this inference.

There is something called the Reynolds number. Through its own formula, it dictates which formula you use for air drag. Is velocity squared (high Reynolds number), or is it not (low Reynolds number)?

Re = (Velocity of travel * Object dimension) / (Viscosity of fluid you’re traveling through)

-> An example of object dimension would be the width of a wing.

The main point above is the Re is always inversely proportional to the viscosity of the fluid you’re traveling through.

Because the viscosity of the fluid we’re traveling through, the atmosphere, is so low, 0.0000146, the Reynolds number for a person traveling through it, or traveling part of their body through it, is always going to be very high. Hence, we go with the quadratic, V squared, formula.

Injuries in sports nowadays

I happened to get an email discussing some of this while I was in the process of writing this post. I thought I’d paste that email exchange for some more real world application.

This email exchange started by someone who is a fan of the Oklahoma City Thunder. Westbrook is Russell Westbrook, one of their star players, who has a history of knee issues, but was playing recently like a born again rare breed.

I’m in regular text; other person is in quotes:


At least Westbrook seems to be fully healthy. I really wasn’t sure he was going to be able to come back and play like he used to. Good for him. Derek Rose unfortunately hasn’t been as fortunate. Tough year for certain players. Seems like these guys are getting hurt more and more.

“Westbrook’s recovery has been somewhat surprising to me, as well. I know one of his surgeries was allegedly to remove a loose stitch. But amazing he can recover even after two knee surgeries. Dude is a freak.

The back to back games are my biggest complaint. This, combined with the conferences and divisions that do not always make geographical sense, make travel a nightmare and (good) rest time all but obsolete.”

The back to back games thing is interesting. I was listening to an interview with Dominque Wilkins about that, and we was talking about how the previous generations never worried about that stuff. Naturally, the previous generations like to talk about toughness yada yada. I don’t think it’s anything with that, but there do seem to be people getting injured more.

May simply be these guys are bigger, stronger, faster now. I’m writing something about this going over how only a small increase in speed gives a large increase in force.

The players are going to have a very hard time changing this though, without taking a pay cut. Less games = Less money for everybody. It’s either that or make the season even longer with the same amount of games. Or take the Spurs route.

“I agree with the older generations talking about toughness in their days. They also walked barefoot to school, in the snow, and uphill both ways. Did I mention their music was also superior and had more meaning back then, too?

I agree that the bigger, faster, stronger will affect injury rates, especially in contact sports like football. But many injuries in basketball are non-contact. But still, these increases are producing more force on the joints which may be leading to the high prevalence of ligament injuries; I get that. However, would an increase in muscle tissue and its capabilities also not increase the ligaments strength? Or are we seeing a point of diminishing returns?

Also, maybe the 24/7 media coverage and availability of online news makes it seems like people are getting injured more but they really are not. I would be interested to see some statistics on this. Either way, the back to back and scheduling of basketball is silly to me. It is scheduled much like baseball, a sport of attrition, while it is much, much closer to football and the impact on the body than it is to baseball. I look forward to reading what you have coming up.”

The reason speed is so important is because there is an exponential relationship between going faster and the forces (squared relationship) imposed on the body, along with the amount of power (a cubed relationship) the body has to generate. It’s why race cars break down, and need a lot more maintenance, than Corollas or Accords, and why pitchers break down more than position players do.

Strength helps, but you can only have so much of it. Things like muscles, which tend to generate propulsion, tend to have a lot more room for hypertrophy compared to joints, which tend to be for deceleration. You can make a quadriceps a hell of lot bigger than you can a meniscus. (Especially when you start factoring in drugs.) With vehicles, it appears you can make engines (muscles) which are often stronger than what the structure can handle (joints). An interesting parallel to humans.

There are some good statistics out there about injury rates being higher nowadays. Baseball pitchers, non-contact sport, are a well cited example. Things like Tommy John surgery are now being called an epidemic amongst the community.

Top sports surgeon in the world, he does a lot more than baseball, discussing it: http://hardballtalk.nbcsports.com/2014/04/10/dr-james-andrews-explains-why-tommy-john-surgery-is-on-the-rise/

There are more reasons than throwing harder, but it’s one of the reasons. There are good statistics on velocities too. Eric Cressey has a lot of good stuff about this:  http://www.ericcressey.com/tag/increase-pitching-velocity

“Perhaps most telling is the fact that between 2007 and 2011, the number of MLB pitchers with an average fastball velocity of 95mph or higher increased from 11 to 35.”

Average bodyweight has also gone up a whopping 20 pounds in the last 25 years.

David Epstein’s The Sports Gene goes into very detailed analysis on how so many sports have become demonstrably bigger. For things like basketball and football, if you don’t fit specific body types, you might as well switch positions or don’t bother. It’s *that* specialized. Certain teams won’t even draft you unless you have things like a particular wingspan.

I can tell you though, the impact of basketball is nothing compared to football. Part of this is because basketball players are actually nowhere near as strong as football players, and subsequently don’t impose the same forces on their bodies. If you look at the vertical jump numbers from each respective combine, football players jump waaaay higher than basketball. And then the contact is of course a huge part.

People talk about all of Kobe Bryant’s injuries throughout the years. His career injury list reads like a typical season or two for many NFL players. They are different worlds. You’re not going to see any basketball players blowing their heads off on a consistent basis, or retiring at 20 years old worried about trauma from their sport. People have no clue what football players are really like. It’s one reason for all the off the field problems they have. They are truly lunatics. The one guy I played with who made it to the NFL and played there 10 years is by far the craziest person I ever played sports with. But it’s what got and kept him there.

Good article on drag, power and speed: http://craig.backfire.ca/pages/autos/drag


Wikipedia and TheEngineeringToolbox.com have more on the Reynolds number.

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