There are about as many theories on muscular strength and endurance training as there are books on Amazon. But, try looking at it through a physics lens. It’s simpler. Strength is the amount of force you can produce and endurance is how long you can keep producing some percentage of force (cardiovascular endurance is a different discussion that I’ll cover later).
When it comes to increasing strength, you only have two main variables: mass (weight) and acceleration (speed).
Strength (or force) = mass x acceleration. I can increase the force by increasing the mass (or for our purposes let’s use the term weight although I know some of you will argue that it’s incorrect…that’s ok – I get it), increasing the acceleration (and, once again, we’ll simplify that to speed), or both.
Exercise physiologists discovered some time ago that you can actually increase your strength by just increasing the speed of your movement. Use the same load but move faster. But why does this work and how do you actually do it?
To build strength you have to stimulate the fast twitch motor units which traditionally has been done with heavy weight due to something called the “size principle”.
The “size principle” states that motor units are recruited in a specific sequence from slow to fast depending on the intensity of the activity.
So, if you lift something light, like a basket full of laundry, you don’t need all of your motor units. You only need a small percentage and those won’t need to generate much tension to lift the basket. So, your higher tension producing motor units have a vacation.
But, if you flip a tractor tire, you need all the units you can recruit which include fast twitch units.
Of course the problem for a lot of people is that lifting heavy things leads to injuring some other things.
And this is one of the reasons, as you age, you get weaker over time. You avoid lifting heavy things, fail to recruit the fast twitch, higher tension units, and your muscles grow weaker. And when you try to reverse it, you hurt yourself.
This is where speed comes to the rescue.
Some researchers studied the firing pattern of the calf muscle1
What they found refuted the “size principle” but instead offered new insights on how your muscles get stronger and you get bigger and faster.
Speed was the key. According to the authors,
“one factor that can lead to the preferential recruitment of faster motor units is rapid shortening velocity of the muscle.”
So, a good alternative for those of you who haven’t trained in a while or are working your way up the strength ladder, is to use a lighter load and move that load rapidly.
Now, be careful. Remember that a baseball pitcher can tear his rotator cuff from throwing a baseball that weighs only 5 ounces.
Usually, you want to use a weight or load that is about 30% of the maximum you can lift, push, pull for 10 times or what’s called a 10RM. So, for example, if you can do a Flamingo Gunner (in the picture to the right) 10 times with a 15 lb load and struggle to do 12 or 13reps, you’re close enough to your 10 RM.
Now take 30% of that load or 5 lbs.
Repeat the Flamingo Gunner but instead of a typical ‘quick up-slow down” movement, you would perform a quick up and a quick down. During the down phase you use your triceps to accelerate the load toward the floor and then your biceps will kick in to stop it and pull the load back up.
Generally sets of 10-15 repetitions are plenty. You’ll see what I mean if you try this subtle but powerful change to a drill like the Flamingo Gunner.
Speed is a short cut to increased strength.