How to Overcome Inertia: Newton's Laws for Strength

I was recently reading a book on biomechanics and in it, the author discussed Newton's Laws of Motion. I was struck at how these three laws can be applied to strength training and habit building. What follows is my attempt to draw some of those lines and make some connections between strength training and the laws of motion (part two will discuss building habits). I'm confident that if you read the article and take a few moments to ask yourself the questions involved that you'll be able to find something that can help you to make positive change.

The First Law of Motion states, “A body at rest will remain at rest, and a body in motion will remain in motion unless it is acted upon by an external force.”
This principle is easily applied to strength training. If you're trying to move a heavy weight, you've gotta do something to it. Looking at the weight doesn't make it move and wishing it would move doesn't make anything happen. To move a weight you need to apply force to make it move.

This rock isn’t moving without a far bit of force, but if you get it off that edge it’s certainly not stopping without a fair bit of force.[/caption]
The Second Law of Motion describes what happens to a body when it is acted upon by an external force. It states, “The force acting on an object is equal to the mass of that object times its acceleration.”
In training, it’s easy to consider the mass of the object you’re lifting, but acceleration is just as important.

An example is the kettlebell swing. I can generate just as much force in a kettlebell swing as I can in a deadlift. The faster I snap my hips, the greater acceleration I apply to the bell, which makes the comparatively light kettlebell punch well above its weight. At one point, Pavel Tsatsouline, the gentleman from whom I learned a great deal of my strength training knowledge, was put on a force plate to measure how much force he generated through the ground with a 24kg bell. The answer? The equivalent of 500lbs (approx. 227 kg). That's a reasonable deadlift to approximate with a bell. So if your hips aren't snapping fast and your kettlebell isn't speeding away from your body, then you're probably cheating your body out of a fair amount of adaptive stimulus!
The Third Law of Motion states, “For every action, there is an equal and opposite reaction.”
At the moment in our classes, I've paired deadlifts with military press. Here's why I did it: I want my clients to understand that the only way to move a weight, whether it is overhead or from the ground, is to generate force into the ground. When people talk about force leakage, what they are actually referring to is the force that has been driven into the ground being put somewhere other than into

Ash and Jeremy demonstrating the deadlift and press at the 2015 SFG in Brisbane. In both cases they are demonstrating a position that is optimal for generating force through their feet in order to shift weight (whether it is placed centrally or off centre they still need to push straight into the floor to create vertical force).[/caption]

the object they are trying to move.

A deadlift is the opposite reaction from my feet pushing into the ground to generate movement through my hips. A press is the same thing happening to generate movement at my shoulder and elbow. Almost all of my lifts improve when I perform them with the relationship of the ground in mind. When I try and pull the bar down on a pull-up I tend to find that my body responds more appropriately than if I try and pull myself up. if I try and push the ground down on a push-up the same thing happens. There is something about attempting to move an immovable object that seems to help my body to make intelligent choices that I wouldn't make when I focus on an achievable or almost achievable end goal.

There you have it! Some of the connections that I thought might be drawn from Newton's Laws of Motion in relation to strength training. Strength is a skill. It’s important to engage your brain and focus on what you’re doing as you strive to move as well as you can and handle whatever load life throws at you. Be deliberate in practice so that you can be awesome in life!

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