Bouncing Out of the Bottom of Your Squat

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Came a question from a reader:

Translation: Daniel, with 5 years of lifting, is doing powerlifting. Hasn't competed but might; they're doing a dry run to peak.

He wants to know if bouncing during back squats helps increase power. He went on to say he heard it might be risky.

Now, this is all a massive "it depends" answer, as usual.

Bouncing your squats is not inherently bad, nor is it bad for everyone. It doesn't mean it's good for everyone either. Let's take a quick look at what the research says, and then look at how and when it might apply out in the wild.

So, a recent study looked at this, comparing back squats with a bounce out of the bottom versus a regular, controlled cadence.¹

They used 0, 25, 50, 75 and 100% of body mass. Which is not a max weight for most competitive powerlifters. But squatting your bodyweight may be difficult for a newbie to achieve. Just something to keep in mind.

Bouncing raised ground reaction force at the turning point by about 40% and rate of force development by about 90%. So, you're going to get a little more output out of the hole. Check.

It also put lifters into more hip flexion, more anterior pelvic tilt and more forward trunk lean (less lumbar extension), which pushed net joint moments up at the hip (+38%), knee (+50%) and ankle (+21%), and roughly tripled the lumbar extension moment (+182%).

On the way up, biceps femoris (+40%), glute max (+37%) and glute med (+28%) all worked harder while quad activity was unchanged.

Two things going on here, and the study pulls them apart.

Load is one. Add weight and activity climbs in everything, quads included, in both the bounce and the controlled version. Within a muscle, higher force demands mean calling on higher threshold motor units, and that part is Henneman's size principle doing what it says on the tin.

The bounce is the other, and it's a different animal. Load was matched between the two conditions, so nothing extra was on the bar. It was position that drove this, not load. Otherwise we would likely see an increase in quad activity as well.

So the bounce turns the squat into a more hip-dominant lift and loads the lower back a lot more, which is worth knowing if you're squatting for quads or squatting heavy and tired.

Again, this doesn't tell you what happens near a true 1RM. My guess is it could increase risk a little bit, but then again, in who? A beginner, or somebody trained, strong and with some specificity and tissue resilience built up?

I think it can help to build some power out of the hole for the turnaround in a heavy squat. I would not do that for everyone, so it really depends on the bag of bones showing up on the day.

I would not have a newbie or a hypermobile teenage girl bouncing her squats, for example.

Though the study does hint at something on the risk question. The bounce advantage got smaller as the bar got heavier. Both ground reaction force and rate of force development dropped off with load, while in the controlled squats load made no real difference either way.

The authors reckon lifters unconsciously back off the eccentric acceleration as things get heavy, which sounds about right to me. I sure do. An earlier study on the same technique at 70 to 80% of 1RM found the force benefit was about half what it was here.²

The lumbar moment and the trunk lean don't go away at heavy loads, but the payoff does.

Also, I don't think it's the only way to train the qualities you’re looking for in other athletic populations. For them, a spell of controlled eccentric heavy reps out of the bottom at times is going to be plenty.

Often, that will be preferable. So that you have those muscles trained to perform out of the deep stretch positions, and not relying completely on getting some assist from momentum or passive structures.

The point here is, even if you're strong and skilled, I'd still use both at different points. For some people, I wouldn't recommend it at all because the juice wouldn't be worth the squeeze, and in some cases might be more risky.

Hope that helps.

– Danny