Leg Press and the Spanish Inquisition
A few weeks ago I was grilled over a Facebook post I’d made regarding the leg press machines found in most gyms. To spoil the ending… I’m not very fond of them. I think they take up space on the floor that would be better used for people to lie down on. The metal that they are made of would be better used in the construction of some kettlebells or a suspension rig.
So why is it that I would never consider putting a client on the leg press machine? Here’s the reasons I gave on Facebook fleshed out a bit, plus a few extra ones.
1) It is a very artificial movement.
It is defined by many leading movement, strength & conditioning and fitness specialists as a non-functional movement. Lying on your back at 45 degrees without the hips opening up, the lumbar spine is forced into flexion… it’s just a flawed movement pattern.
2) Leading on from that, it’s going to damage your back.
Dr Stuart McGill, the leading authority on spines but also a leading consultant on physical preparation (US and Canadian Military, Police and Fire Services all utilise him ) doesn’t like it. And McGill is one of those people who will back up his opinion with science.
The seated posture forces an anterior curve in the spine. This, coupled with the large force being resisted, is pretty much a recipe for an posterior prolapse of one of the lumber vertebrae.
The common analogy is that the discs in your spine are like doughnuts. A hard gristly outer with a gooey inside (ok, maybe a two day old doughnut). The discs are stacked alternately with the spinal vertebrae, parallel to this runs all the nerves and stuff that allow you to control your body. By forcing the spine to curve forwards and putting a large pressure through it, you’re basically squeezing one side of the doughnut. A severe enough ‘pinch’ and a large enough force and ‘squirt’ that goo has to go somewhere!
Basically… it’s going to break your back.
3) Not so much a reason not to do it but… many big guys, who are for some reason scared of squatting, prefer the leg press because they get ‘a bigger number’. Yes, you can leg press more than you can squat. But look at point (2). That said, that big number they leg press is a lie. There. I said it. Allow me to explain.
You brag to your friend who has a 140kg back squat that you can get 170kg on the leg press, ergo you have ‘stronger legs’ than him (or her).
That 170kg is going down a 45 degree angle. Assuming zero resistance from friction in the rails (which you’d have to overcome going back up, so I’ll give you that) the force resisted by the ‘incumbent’ is:
170 sin (45) = 120.2kg
So you’re weak.
4) You don’t achieve full extension of the hips.
The Range of Motion (ROM) is only partial. This can potentially lead to muscular imbalances (unless it’s being used as some form of remedial, but then I’d direction you to points (1) and (2)).
5) The torso/core is underworked.
There is very little load carried by the torso because the hips are wedged into the seat. This is the classic failure that most weight machines are know for, the fact that they isolate a limb from the rest of the body. This is like trying to put monster truck tyres on a classic mini cooper. Even if you somehow managed it, the poor little engine is going to constantly stall because it can’t generate enough torque to overcome the huge inertia of the wheels.
Addendum: Hack Squat machine….
I was subsequently asked about the hack squat machine: “Because it’s the same thing isn’t it?”. Yes and no. Hack squat machines tend to come in more varieties of shape and geometry than leg press machines. The closer to vertical the rail is, then the more load you’ll actually be carrying.
The back is again forced into a compromised position, due to the fact that the hips cannot move ‘backwards’ relative to the position of the heels. Arguably the back is in a safer position in the hack squat machine than the leg press, as the spine isn’t held at 90 degrees to the line of force. So you’ll get less spinal flexion at the bottom of the movement, but it’s far from optimal. Also, again you don’t get full ROM of the hips/glutes.
It’s a very artificial position.
Kids, just say no to the leg press and hack squat machines.
Say yes to exercises like:
Barbell/Kettlebell front and back squats
Deadlifts and deadlift variations (Sumo, single leg)
Lunges
Loaded carries
Whereas in the leg press machine there is very little load carried by the torso, not only will the above exercises work ‘the legs’, the torso will be put under load which leads to further awesomeness.