The Mechanics of Barbell Training

Barbell training consists of moving loaded bars through space with
our bodies. The most effective way to do this is to simulate normal
human bilateral movement patterns that use as much muscle mass and
effective range of motion as possible. If strength is the ability to
produce force, then the amount of force production directly measures
strength – the weight on the bar is exactly how strong you are. If
that goes up, your strength increases. The best exercises are the
movements that allow you to lift the heaviest weight, while
incrementally increasing it over time.

When you train with a
barbell, it becomes immediately apparent that there are both
efficient and inefficient ways to move the load through space. The
science of Mechanics studies the relationships between forces and
physical objects, and barbell training is essentially applied
mechanics. It is important to realize that the physics of applying
force to an object in your environment is subject to rational
analysis, and your personal preferences have no bearing on the “right
way” to do it.

Gravity affects both
you and your barbell, and everything else around you. Gravity is the
attraction between objects, and is proportional to their mass. Since
the earth is an object, and your barbell is an object, and you are an
object, all three are attracted to each other by gravity. But since
the earth is the biggest, it wins every time, to the extent that your
barbell’s attraction to you, and you to your barbell, is quite
insignificant. When you do work on the bar, you are doing work
against the earth. Since the earth is a sphere, the center of its
mass is the middle of the sphere, which is always in the
direction of a vertical line down into the floor.

The earth attracts the
bar with a force equal to the “weight” on the bar – its mass.
Kilos are units of mass, and pounds are units of force. If you load
100kg on the bar, it “weighs” 220 pounds. If it is on the floor,
to pick it up you have to apply more than 220 pounds of force between
the floor and the bar. If you apply 221, it moves up slowly, and if
you apply 405 it moves up fast enough to clean it – the higher the
force applied, the greater the acceleration and the higher the
velocity. So the stronger you are, the more you can deadlift, and
the more you can clean.

The force you use to
lift the weight is produced by the contraction of your muscle mass as
it operates the system of levers that is your skeleton. Your
musculoskeletal leverage system operates just like any other leverage
system: it uses a point of rotation to redirect and amplify an energy
input along a rigid member, so that the output varies in magnitude
and direction. Like a crowbar (or really, a system of multiple
crowbars), your system of levers can be used efficiently, or

Its efficiency is
determined by how much of the energy input lifts the load, and how
much of it is wasted in working against the levers themselves –
could the same energy input lift more weight were the levers
positioned differently relative to the load? The correct position
from which to apply force to the load is discoverable, it is
coachable, and it must be learned by the lifter if winning the meet
is the objective. 

Here is a very simplified example: if you are using a shovel to move dirt from one place to another, you stand as close as you can to the dirt you’re picking up, and then you use the length of the shovel to throw the dirt to the new pile. It’s easier to pick up the dirt if you’re standing closer, with the shovel closer to your feet. The hand gripping the handle closest to the blade of the shovel acts as a point of rotation, while the other hand on the end of the handle operates the longer lever. The distance from the “long” hand to the “short” hand is a lever arm – the distance between the application of force and the point of rotation – and the distance from the “short” hand to the shovel blade is also a lever arm. The long lever operates the short lever by multiplying the force over the longer distance and causing the load to move over a shorter distance.

Using a shovel as a Class I lever. Lever arms form between the load and point of rotation (red line) and between the back hand and the point of rotation (blue line) as the shovel is used to lift the dirt away from the pile.

A shovel is a simple machine that can be used as a lever in several ways. With shovel blade shoved into the ground and the force applied at the end of the handle rotating the dirt up against the bend in the blade, or when picking up the dirt as it rotates in the front hand, it is used as a Class I lever. But it can be used as a Class III lever when throwing the dirt after it has been picked up.

shovel used as a class 1 lever with poor leverage

Using a shovel as a Class I lever from a disadvantageous position. Note that the lengths of the lever arms have changed compared to the image above, making the load more difficult to move.

But the distance between you and the dirt must be considered as well. You and your shovel are a machine, not so simple, that moves the dirt. The distance between you and the dirt affects the efficiency with which the shovel moves the dirt. If the dirt is 4 feet away, the leverage efficiency of the shovel is compromised because your “short” hand is no longer close to the shovel blade (since you have to reach the dirt), and the leverage against the dirt is diminished drastically – in fact, the dirt now exerts more leverage against you, since the dirt now has the longer lever. If the dirt is 4 feet away, you cannot keep your “short” hand grip on the shovel because you will be off-balance forward. So your “short” hand is now much longer, and you cannot operate the shovel with anywhere close to as much weight in the blade as you can standing close to the dirt.

The balance issue must be kept in mind. You are “in balance” when the load you are moving is over your feet – you cannot hold a 100-pound dumbbell in front of you at arms-length without leaning back, because it will pull you forward as the mass of the dumbbell changes the balance point of the system. And this is true whether you are working on a loaded bar or a basket of parts in your garage. The heavier the weight you are handling, the closer to a vertical line over the middle of the feet you and the load must be.

This is simple freshman mechanics, and it applies to barbell lifting as well. Taking the deadlift as an easy example, the most efficient place to pull the bar from the floor is where the barbell is directly over the middle of the foot. If you are standing “in balance” – i.e. not falling down and not leaning on anything – your body’s “center of mass” is directly over your mid-foot.

Adding a barbell to the system doesn’t change this fact, because the weight of your body and weight of the bar together interact with the floor under your feet. If you squat down and stand back up and don’t “lose your balance,” you have maintained this alignment relationship.

Any other position represents inefficiency, which should be thought of as force production not directly contributing to moving the load upward. If you pull a loaded bar off the floor, any force applied that does not directly contribute to the upward movement of the bar is inefficiency relative to the task of pulling the bar. If the heavy-enough bar starts the pull forward of the middle of the feet, it must be pulled back to the mid-foot point before the musculoskeletal levers can exert enough force to pull it off the floor. All the force and work involved in getting the bar back into the correct position is wasted, because you started from the wrong position.

The heavier the load on the bar, the more the pull must conform to this alignment, and the lighter the load the more deviation from this alignment it can tolerate. A heavy deadlift can be pulled only one way, while a clean or a snatch can deviate considerably. But even a submaximal pull like a clean or a snatch is pulled more efficiently from over the mid-foot.

Heavier weights can be cleaned and snatched when pulled correctly because 1.) more force can be applied in a better leverage position earlier in the pull because it is not being wasted getting the bar and your hips, knees, and shoulders into the correct alignment, 2.) that not-wasted force can be applied to the acceleration phase of the pull below the knees, and 3.) a bar accelerated efficiently through more of the pull is moving faster that it would be if pulled inefficiently. This results in a bar pulled higher with the same weight or a heavier bar pulled to the same height.

The reason this discussion is important is because barbell training is essentially a math problem. Its mechanics are discoverable, coachable, and can be mastered by the lifter if the coach can explain it correctly. It should have nothing to do with your personal preference (“It’s always worked for me”), or your perception of how the greatest lifters in the world do things, all of which are irrelevant. Mechanical systems behave in specific ways, there is a logical way to analyze every lift, a logical way to coach that analysis to every lifter, and a way to observe and correct errors based upon the model of the lift you coached. This is the basic function of a movement coach, and you should learn how to do it.

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