Q: I was doing my stuff at the gym the other morning, and a woman who is a trainer there, saw me doing reverse lunges. She came over to me and said that when I do my lunge, not to let my knee touch the ground, that it should be just above the ground. “This is how ACLs get injured,” she said. She also said to try to shift weight to the front of your foot, and not let the knee touch.
Personally, on that issue, I think having more pressure on the front of your foot would cause knee strain, especially right under the knee cap and right above on the quad. But, what do I know? I said thanks and continued with my stuff. Thoughts?
A: Actually, you know more than you think. Which is that you ignored her advice and continued with your training session. Although it would have been perfectly understandable if you punched her in the ACL with a 5 lb dumbbell for interrupting you with such nonsense.*
Concerning the latter part of the question, you’re correct. Shifting your weight to the front of your foot and pushing off the toes will undoubtedly place more strain on the knees. Sure it will increase quad loading, but what’s good for quad loading might not be good for knee health. I like to instruct people to shift their weight to mid-foot/heel, which will take some of the burden off the knees and place a little more emphasis on the glutes/hamstrings.
Concerning the former part of the question, honestly, I have no idea what her rationale might be for stating that allowing your knee to “touch” the floor while performing a reverse lunge predisposes you to an ACL injury. The primary function of the ACL is to prevent anterior displacement of the tibia off the distal end of the femur. The ACL, along with the resistance of the posterior muscles crossing the knee joint (hamstrings), prevents the normal knee from hyperextending. How allowing your knee to touch the ground while performing a reverse lunge places the ACL at greater risk is beyond me.
If anything, telling people to gently touch their knee to the ground keeps them honest (key word: gently). If you tell people to stop 1-2 inches short of the ground, that’s going to inevitably turn into 3-4 inches. And before you know it, they’re not doing anything remotely close to a proper lunge. That’s a big reason why I’m such a fan of box squats; it forces people to learn what proper depth is supposed to feel like.
Just to be clear, however, there are plenty of compensation patterns that can predispose you to an ACL injury while performing a lunge (knees caving in due to weak glutes for example). But to the best of my knowledge, having your knee touch the ground isn’t one of them. Mike Robertson wrote a great article on this topic here. I encourage you to check it out.
In the end, my hunch is that she’s a trainer at a local commercial gym and was just trying to sound smart by using a term that would scare you or get your attention and hopefully lead to a conversation that ended with you buying a few sessions from her. It’s like me telling a 17 year old kid that he’ll increase his testosterone levels by 583% if he drinks, I don’t know, powdered deer penis. True story
*Hahahahaha. Irony is a bitch.
