Think about the last time you did a heavy barbell back squat.
You took the barbell off the rack, walked it back. Your hips push back and down, lowering the weight while maintaining posture and position with a strong torso. You hit the bottom of the squat and activate your lower body to lift the weight and come out of the "hole."
You fight the weight inch by inch until you're about half way up, and suddenly that barbell is much easier to return back to the standing position. The hard part is over, so we coast back up with relative ease. Sounds about right?
Why does it become so much easier half way up? The load on the barbell certainly hasn't changed.
That halfway point as you stand back up (the concentric phase of the lift) is where you're bone structure and supporting musculature have a greater mechanical advantage compared to the bottom of the squat. All of the muscles in the posterior chain, adductors, and quad's work in unison with relative ease at this point.
So what do most of us do when the hard part of the lift is over in the second half of the concentric phase? We get lazy and move nice and slow back up to the standing position.
This is where the theory of Compensatory Acceleration Training (CAT) comes into play.
This theory, originating from Fred Hatfield and expounded upon by Mel Siff, proposes that accelerating the speed of the lift during the concentric phase, especially in the top half of the lift we discussed, allows for maximal force generation at submaximal loads.
So, to put it simply, you lift the bar as fast as you can coming out of the hole back to the standing position. If you're doing it right, you'll hear a 'clink' at the top of the lift of the weights on the barbell shifting ever so slightly.
(Don't dive bomb down to the bottom - this is a technique used by some in powerlifting but risky for the vast majority of us. Control the weight in the downward eccentric portion).
This technique has several benefits:
- We're now using maximal force throughout the duration of the lift, maximizing efficiency to properly overload the system for adaption (i.e. getting stronger).
- We're recruiting more fast-twitch muscle fibers (as opposed to slow twitch) to execute the lift.
- In terms of performance, the application of strength outside of the gym is done through applying your strength through power. The carryover with CAT is greater than a heavy, long lift.
- We can use less weight to train maximal strength. By lifting the load with maximal velocity (mass x acceleration = force... according to some dude named Newton), the amount of force generated by a CAT lift at submaximal load (60-80%) is equal to or greater than the heavy, long lift. Hatfield squatted over 1,000 lbs using CAT, with training loads which rarely exceeded 800lbs.
This technique doesn't just apply to the Back Squat. Any compound movement can be conducted with the CAT principle. If you're going to give it a whirl, do some practice reps to ensure you don't explode off your feet. Stay totally grounded and in control of the barbell while still applying max acceleration.