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Starting Strength in the Real World

Comparing the Deadlift and the Power Clean After the Floor

by Jordan Burnett, SSC and Mark Rippetoe | October 22, 2019

There are many differences between the deadlift and the power clean, most notably and obviously that the deadlift is pulled from the floor to arms' length on the thighs, and that the power clean is accelerated off the floor and racked on the shoulders. The deadlift is a slow lift that is focused primarily on maximum force production, whose main objective is to increase the strength of the muscles of the posterior chain. The power clean, on the other hand, trains the expression of strength as power.  

Power is simply the ability to express strength quickly. The setup for these two lifts is identical. They both begin off the floor in deadlift mechanics: the hips are high, the shins are nearly vertical, and the shoulders are slightly over the barbell. At this point you might think: “Since the setup looks exactly the same on both lifts, they must be executed pretty much the same way. The only real difference is the weight on the bar and that the power clean has to get racked on the shoulders. Simple, right?” Wrong. There’s a subtle, but crucial difference between the execution of both lifts after they leave the floor. But first, a brief recap on basic barbell physics. Buckle up, kids.

There are essentially three kinds of forces that are acting upon the lifter/barbell system during a lift: compression, tension, and moment (or rotational) force. For this explanation, we’ll be dealing primarily with the concept of moment force. There are some other terms to be familiar with: the barbell is the point of force application at which gravity is producing force downward against the load that rotates the joint, or the fulcrum, the point of rotation. The horizontal distance between these two points (since gravity operates vertically) is called a moment arm. A wrench turning a bolt is a good example of how moment force works.

So what does moment force actually do? Simply put, it causes rotation about an axis. Let’s look at it in the context of the squat. The hip joint is the fulcrum, and the point of force application is where the barbell is being carried on the back. The horizontal distance between the hip joint and the barbell is the moment arm. When the hips and knees start to bend and the back angle becomes more horizontal, the barbell and the hips move farther away from each other horizontally, which causes the moment arm to lengthen. The longer the moment arm, the more force the lifter has to apply in order to stand back up with the weight. In other words, the more moment force there is to overcome, the harder the system will have to work to finish the lift.

The goal in the deadlift is to reduce the length of the moment arm across the back segment as quickly as possible. Why is this? Because the gravitational force that is being applied by the barbell multiplies as the moment arm grows longer, or in the case of the deadlift, as long as the moment arm across the back segment happens to be when we properly set up to pull the bar. Shortening the moment arm between the hips and the barbell by lowering the hips and making the back segment more vertical might seem to be a sound strategy for making the lift easier. Unfortunately, the hips are connected to the knees via the femurs, and if the hips move down, the knees go forward, and the barbell is pushed in front of the mid-foot. There is still a moment arm between hips and barbell, but now some of it is placed in front of the mid-foot balance point and on the knees, away from the large muscle mass of the posterior chain. If you’re able to break the weight off the floor, you will have done so after raising the hips back up to where they should have been with the correct, more horizontal, back angle.

starting strength deadlift drawing

The deadlift and the clean differ once the bar leaves the floor. Remember that the deadlift is a slow lift, so we’re not necessarily concerned with accelerating it off the floor after we get it moving up. As soon as the knee and hip extensors do their job of breaking the bar off the floor, the goal should be to shorten the distance between bar and hips. Since lengthening the moment arm multiplies the force needed to move the load, then shortening the moment arm will divide it, making for substantially less rotational force across the back segment as the bar comes up.

Now, let’s compare these mechanics to those of the power clean. The power clean is a fast lift. It is accelerated off the floor quickly with a submaximal load. Because the load is light enough and because you are strong enough, the force produced between the floor and the barbell by the muscles of the hips and legs can cause the bar to gain enough momentum to continue moving upward even after those muscles have stopped producing force.

starting strength drawing moment arms in the clean

starting strength hip class 1 lever

The execution of the power clean is often compared to mechanics of a trebuchet. The trebuchet was a medieval siege engine (vastly superior to the catapult) that utilized a counterweight system to fling projectiles across great distances at whatever poor bastards happened to be in their firing line. In order to fully understand why this is important, we need to talk about levers. The hip joint is a Class 1 lever, meaning that the fulcrum is placed between the load and the force that moves it. The rigid segment of a properly extended strong back is what transmits the force. If one side of the lever is shorter and the other side is longer, as is the case with the hip joint, the shorter side will move a shorter linear distance more slowly, while the longer side will move a greater linear distance more quickly, even as both sides cover the same angles. The muscles of the posterior chain are the force pulling down behind the hips, the short segment, and the load in your hands is the force pulling down in front of the hips along the back, the long segment. The short side, with enough force behind it, can move a short distance and make the load being carried in front of the hips accelerate over a longer distance, much like a trebuchet.

This is exactly what happens in the power clean. A more horizontal back angle – and thus a longer moment arm and more moment force, if you're strong enough to generate it – is maintained throughout the pull in order to better capitalize on the powerful triple extension of the hips, knees and ankles, producing acceleration that carries the bar high enough into the air for the lifter to rack it on the shoulders. This much acceleration is not necessary for the deadlift, since it locks out at the thighs, and that is why much heavier weights can be deadlifted. The clean maintains a long moment arm for acceleration, while a deadlift can dump the longer moment arm as the bar comes up the legs so the heavier weight can be locked over a much shorter range of motion.

Acceleration is the difference between a deadlift and a power clean, and the maintenance of a longer moment arm – “staying out over the bar” – is the tool used in the clean to “whip” the bar through the pull. 

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