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“There is simply no other exercise, and certainly no machine, that produces the level of central nervous system activity, improved balance and coordination, skeletal loading and bone density enhancement, muscular stimulation and growth, connective tissue stress and strength, psychological demand and toughness, and overall systemic conditioning than the correctly performed full squat.”
Mark Rippetoe

Your 630lb leg press with all the plates in the gym (okay maybe not all, but that is still 14 plates), doesn’t equal my 335lb squat (using only 6 plates, the bar and a couple of 10 lbers). It doesn’t even come close. There, I said it.

Taking and using every 45lb plate in the gym may make you feel like a badass, but I promise you that you aren’t making a lift of 630lbs. Now if you are the kind of person that plate hoards like this you probably are not so good at math. That said, I’m going to show some simple trigonometry to calculate the vertical weight being pushed.

Leg Press math

sin45 The leg press platform is restricted to a 45 degree angle on a fairly frictionless slider. Because of this the vertical weight being pushed is equivalent to:

weight x sin(angle) = 630 x sin(45) = 445lb

But wait, that is still more than my measly 335lb squat.

Squat Math

Not. So. Fast! You forget too that you are laying down and aren’t actually lifting any of your body weight through the movement. Therefore your lift remains at 445lbs. I weigh 175lbs, and I am also raising a good portion of my body weight up with the bar (lets say about 65% of it). Therefore I am lifting an additional 115lbs more or less (probably more).

So where do we stand? Your 630lbs press is actually only 445lbs. Whereas my 335lb squat is actually 450lbs.

You don’t have a leg to stand on!

But we are both annihilating the idiot doing the single leg pistol squats with a 75lb dumbbell in the corner, right? Actually not so fast. Lets go to the math again.

In the examples above, we need to divide by two in order to give us our lift per leg.

Leg press (per leg) = 445/2 = 222lbs
Squat (per leg) = 450 / 2 = 225lbs

Now in a single leg squat we are lifting a greater proportion of our body weight, closer to 85% of it.

Single leg squat = (175 * 85%) + 75 = 224lbs.

But that’s STILL rather close

Arnold-Squat1-300x233Lets summarize the math

  • 630 lbs leg press (14x45lb plates) = 220lb lift
  • 335 lb squat (6x45lb + 2x10lb plates) = 225lb lift
  • 75lb pistol squat (single kettlebell) = 224lb lift

The more observant among you will remember that I said my squat was so much better than your leg press, and yet mathematically I have shown them to be almost identical.

While the lifts are identical in terms of weight, the leg presses don’t even come close in terms of muscle activation, total body hypertrophy, and even specifically hypertrophy in the quad muscles (even though these are targeting the quads specifically) than the squats.

From a hormonal perspective the data is very clear. Squats produce a larger hormonal response, period.

Some citations

Additionally, the math above assumes that all muscle activity is equal, and that we are simply dealing with the trigonometry used to calculate force vectors in line with the pull of gravity. This simplification doesn’t tell the entire story, such as differences in how muscles activate – particularly when comparing single and double leg variations.

What else?

1377094_10204605946413342_279656754722132243_n Lets take the quads out of the picture. Something hard to do if you have the impressive quads that squats will give you. We are taking them out of the picture just to see what else gets activated.

Studies have monitored the effect of the squat and leg press on other muscle groups, for example the University of North Dakota measured activity in the erector spinae (the muscle groups that surround and protect the back), the gluteus maximus (your ass), vastus laterallis (outer quad muscle) and the biceps femoris (outer hamstring).

The quad (VL) showed slightly more activity while all other groups showed significantly greater activity during the squat.

From my own experience, my core, upper and lower back and other surprising muscle groups get hit better by the squat. Additionally the restriction of the movement plane for a leg press might have ergonomic implications.

Mark Rippetoe’s quote at the head of this article then not only holds true from experience, from common sense, but also scientifically.

So stop the press?

So I should stop doing the leg press then? Well again, not so fast. It has its place.

For example if you are rehabilitating a back injury a properly executed leg press can cause significantly less stress on the spine than a squat. However in these cases, I prefer to reduce the load on my back instead by doing single leg squats.

Bio-mechanics also come into play. I am short, but strong. I am therefore bio-mechanically at an advantage when it comes to the squat due to smaller levers. A taller person might have a significant disadvantage due to longer levers in their skeletal system and therefore just not able to lift as heavy with a traditional squat even with comparable muscle strength.

The leg press also makes a great “finisher” exercise. I find that my legs tend to fatigue at a slower rate than my core. Once my core fatigues, it does a worse job of protecting the lower back, and therefore my form becomes at risk. Finishing a round of squats with some heavy leg presses is therefore on the menu from time to time. Its worth noting that I have more recently worked to improve the strength and endurance of my core muscle which have in turn helped my squat.

Finally, some douchebag is probably doing curls in our squat rack.

Therefore the leg press is a great addition to the arsenal of squat variations, but should never ever replace them.

References

You can do much much worse than listing to Mark Rippetoe. If you haven’t read his book Starting Strength I encourage you get it now.

This article doesn’t go into the key point that Rippetoe is careful to specify regarding a “correctly performed full squat”. Check out Stronglifts excellent post for descriptions and videos on how to perform a correct full squat.

 

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