Lunges vs. Leg Press: A Discussion at PHP

Image courtesy of rookiejournal.com

Last week Friday during study group at Precision Human Performance we had a really great discussion about why we would have a client or ourselves perform a lunge as opposed to a leg press.  For this discussion, we defined lunge as something that looks like this:

Ahh, college.  Okay so not the greatest video but I guess at the time I thought it was obvious what was going on with my legs and feet, even though they are completely out of the frame and arguably the most important part.  Fortunately, there are plenty of other videos of lunges on YouTube, almost all of which are much more entertaining than my own, so check those out if you need further clarification.

Then, for leg presses, we are looking at something like this:

Once again, a brilliant display of control in this video...

Okay, so the discussion started by Michelle Amore posing the question of why we would put somebody on a leg press.  Interestingly, when we broke everybody's responses down, it all came down to muscle in some regard, whether it be building it, controlling it, or biasing it (for more on this, take RTS™).

Once that was established, the discussion turned to which movement allows us to build, control, and/or bias muscle more efficiently and effectively in addition to identifying the difference between performing a leg press and a lunge.  We discussed the mechanics of each, how a leg press may have the ability to keep the challenge of performing the motion relatively high throughout a given range of motion while a lunge is often only really difficult at the bottom of the rep from a mechanical standpoint, depending on how low the individual is able to drop.

Most importantly, we discussed the differences in the amount of passive restraint typically imposed during each and how the less passively-restrained lunge dictates that less weight can be handled throughout the motion, which may ultimately mean less tension will be allowed to be generated by the muscles in order to perform that motion.  Likewise, the leg press with its higher degree of passive restraint allows for the user to almost lock themselves into the position so all of their energy, effort, and force can be directed towards performing hip and knee extension.

Think of this as similar to doing dumbbell presses on a stability ball versus on a flat bench.  If you measure the 1 rep max of each situation, you are almost always going to find that more weight can be pressed while lying supine on a bench (more passive restraint) than on a ball (less passive restraint).  This goes back to the discussion back in January about balance and how balance is a skill and, more relevant to this post, if your balanced is challenged in any way the number one goal of your brain will be to keep your center of mass over your base of support.  This means that if you create a scenario where keeping your center of mass over your base of support is no longer a challenge because of the imposed restraint, performing other tasks or motions can begin to take greater precedence.  However, without that passive restraint locking you in, ensuring that you maintain your COM over BOS will trump the execution of any motion attempted.

The takeaway message from all of this is the less passively restrained a motion is, the more the execution of that motion becomes a skill.  Bringing it back to the initial goals of the exercise, if we are performing this motion in order to build, control, and/or bias specific muscle tissue, attempting to achieve these goals by performing a skill is going to be less efficient than locking ourselves into a machine and shoving with everything we have.  However, if the goal is to improve the skill of lunging, then lunges would certainly have their place.

What are your thoughts on the Lunges vs. Leg Press discussion?  Drop a comment below!

Want to join in on the Precision Human Performance study groups?  Email info@precisionhumanperformance.com to get the GoToMeeting.com id!

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