“What makes a car move?,” my high school physics teacher once asked us, through her usual quirky grin.
It was a trick, and we knew it. “The engine?” a few of us mumbled hesitantly.
“Nope”, she replied, smugly, still grinning; “try again.”
The next five minutes or so were spent randomly naming car parts until one of us finally mentioned tires.
“Bingo: everything else that makes up a car,” she explained, “the transmission, the radiator, axels, wheels, even the engine, is devoted to the task of making the tires spin. The tires, as the only points on the car that make contact with the road, are the only parts capable of producing motion.”
A similar thought experiment can be done with bodies. Imagine, if you will, someone carrying a watermelon. A watermelon requires effort to lift; so, where does the lift come from?
For those of you thinking “biceps” or “shoulders”: nope. I’ll give you a hint, though: the answer isn’t a muscle at all.
It may sound obvious to say it, but there are no muscles attached to our hypothetical watermelon. In fact, muscles absolutely can not act on any object or surface outside the body. The only thing a muscle can act on is a bone. Period.
Bones, however, actively conduct force from the outside world through the body. By aligning bones properly, force can be carried more efficiently through the joints, maximizing the output of work while minimizing the energy required to do it.
So, when carrying a watermelon, what you’re really doing is using your arm bones as levers, which in turn are using your rib cage as a lever, which is using your pelvis as a lever, which is using your leg bones as levers which are using your big toes as levers which are using the earth as a giant fulcrum.
The reason for this is something called the normal force. Simply put, If you are standing on a surface (that isn’t collapsing), that surface is necessarily exerting on you an amount of force equal but in opposition to the force of gravity. That’s right, the earth pushes on you. If you think of this force as being like electricity, your bones are like copper wire, conducting that force and putting it to use.
The role of muscle, then, is to align bones to ensure maximum conductivity. A muscle can only be called “strong” if it is good at moving a loaded bone into optimal alignment with the other bones to which it is attached quickly and smoothly. Conversely, a muscle that has been trained into being large, even bulging with torque capacity, cannot be considered strong if it does not fulfill its function as an agent of skeletal alignment.
This fact has been exploited by martial artists for millennia. Why should I burn energy to strike an opponent with my hand when I can expend a fraction of a fraction of that energy and literally let the floor hit my opponent through my hand?
Whether or not you frequently engage in epic kung fu death matches, training muscles to facilitate the force conductivity of bones is still the most efficient and effective use of your energy. Of course, muscles can be trained to become hulking mini-engines, but, you know, a screw driver can also be used as a hammer; it’ll do the job, but you’re working too hard and will probably end up breaking your stuff.
When engaging in any activity designed to make you stronger, consider carefully what that word actually means and ask yourself the following questions:
Does it hurt?
Normal, functioning joints do not hurt when they move. Ever. Not even under maximum load. If you’re concerned that your joints are somehow damaged or compromised, there are options available for training that can mitigate pain and joint deterioration while also making you stronger.
Does it hinder my mobility?
Strength and flexibility are the same thing, or rather, they are mutually dependent: you cannot have one without the other. If a muscle is only “strong” over a short range than it cannot facilitate bony alignment outside of that range. This creates pockets of instability that your body will naturally avoid during movement, leading to progressively less mobile joints. Joints maintain themselves through use, meaning that a lack of joint mobility is a decrease in joint longevity.
When I’m finished, what will it take to recover?
If the answer to that question is anything other than rest and food, you may be in dangerous territory. Ice packs and anti-inflammatories are for injuries, not workouts.