I tore my left knee ACL 6 months playing soccer. After the incident I was able to go to a Dr and he told me I need to let the inflammation come down and then get surgery. He said I don't need to do the surgery to live a healthy life but if I want to play sports with twists and turns (like soccer, basketball, etc) I will need the surgery.

The Dr told me I could run, jog, swim, and do many other things with a missing ACL. And I am doing all those right now. He said before the surgery I should strengthen my leg muscles because it will improve recovery post-surgery.

I do plan on getting the surgery (sometime in the future) but I just want to know if squats and deadlifts are one of those things that its okay to do with a torn ACL? Technically your moving up and down in those exercises, no twists or turns, but is the weight and pressure at all harmful on this part of the leg/locomotion system given a missing ACL?

I just started lifting since the incident and I just want to know. I recently relocated and will be seeing a Dr soon about this but until then...

  • 6
    I've heard that Mark Rippetoe squats without a ligament these days, but I wouldn't advise it for someone who doesn't have near-perfect form or excellent coaching. Disclaimer: I have no actual expertise in this matter. Dec 20 '11 at 21:28
  • Agree with @DaveLiepmann. Rippetoe warns about the dangers to ligaments when squatting with bad form. He also strongly recommends the squat when done with good form, even with a missing ACL. Hamstrings will prevent the tibia from moving forward relative to the femur in a full squat (not in a partial squat... you have to drop all the way down for the hamstrings to help in that way). He doesn't mention anything about the deadlift, though.
    – user2567
    Dec 21 '11 at 21:31

Squats can be done safely with an injured ACL.

In Effects of technique variations on knee biomechanics during the squat and leg press (also available here for free), the authors found that "no ACL forces were produced for any exercise variation" of the squat or leg press, and that "the lack of ACL forces implies that all exercises [squats and leg presses] may be effective during ACL rehabilitation".

In Knee biomechanics of the dynamic squat exercise, the authors conclude:

The squat was shown to be an effective exercise to employ during cruciate ligament or patellofemoral rehabilitation. For athletes with healthy knees, performing the parallel squat is recommended over the deep squat, because injury potential to the menisci and cruciate and collateral ligaments may increase with the deep squat. The squat does not compromise knee stability, and can enhance stability if performed correctly.

(By parallel, this means tops of the thighs parallel to the ground.)

The deadlift also.

From A three-dimensional biomechanical analysis of sumo and conventional style deadlifts:

Because the deadlift is considered a closed kinetic chain exercise (23), it can also be employed in knee rehabilitation programs, such as after anterior cruciate ligament (ACL) reconstruction. Numerous studies have already shown that the squat is an effective exercise during ACL rehabilitation (11,15,20,22,25,26,29). Because the deadlift is performed in a similar manner as the squat, it is hypothesized that the deadlift may provide similar benefits during ACL rehabilitation. The moderate to high hamstring activity that has been reported during the deadlift (28) may help protect the ACL during knee rehabilitation. However, which deadlift style would be most effective in knee rehabilitation has not yet been established.

Leg extensions are not recommended for an injured or recently reconstructed ACL.

(You didn't ask about leg extensions, but jp2code suggested them, so I'm correcting that here.)

Many studies (for example, Electromyographic Evaluation of Closed and Open Kinetic Chain Knee Rehabilitation Exercises) have shown that open kinetic chain exercises (leg extensions) produce significantly higher shear force at the knee joint. These shear forces result from increased quad tension and can direct too much force through an injured or reconstructed ACL. The authors cite 10 other authors that warn against open kinetic chain exercises after ACL reconstruction. "Because [...] shear forces are are increased during leg extensions, it seems prudent to select alternate exercises to strengthen the quadriceps after ACL reconstruction."

Regarding closed kinetic chain exercises (that includes squats), they say "weight bearing, closed kinetic chain exercises cause less elongation of the ACL than non-weight bearing, open kinetic chain exercises", and "closed kinetic chain exercises have been found beneficial in ACL rehabilitation programs".

One doctor's ACL rehabilitation program goes so far as to say "the leg extension machine should never be used because it will significantly aggravate your PF pain and can cause severe ligament injury" (emphasis theirs).

Later on in recovery, inclusion of leg extensions can assist in regaining quadricep strength and an earlier return to sport (from Closed kinetic chain alone compared to combined open and closed kinetic chain exercises for quadriceps strengthening after anterior cruciate ligament reconstruction with respect to return to sports: a prospective matched follow-up study), but the authors of that study agree that unrestricted open kinetic chain exercises could put too much strain on the ACL and suggest a wait until 6 weeks and only include them under controlled conditions.

Other references

Here's a less scholarly reference that gives a good summary of the forces on the ACL during squatting and leg extensions: http://www.lookgreatnaked.com/articles/archive/1003article.htm


Squatting actually helped me recover the normal use of my leg. I tore my ACL 10 years ago and suffered a failed autograft surgery where the surgeon cut out the middle 1/3 of my patella tendon and used that as the acl replacement.

The surgery failed and my knee cap shifted out-of-place because of the cut petella tendon. After 10 years, I was suffering from patellar tendonitis. My involved leg was much weaker and had a drastically reduced range of motion which caused a poor gait and all kinds of foot and hip pain.

The surgeon told me to never squat, but I figured that my leg was so messed up anyway after 10 years I might as well try it. Well, the more I squatted the better the leg got. I started out with light weights for high reps to get the range of motion back. As soon as the range of motion returned, I started ATG front squatting and then slowly adding weight on the back squats.

Now, 3 years later, I just PRed 605 pounds on the back squat and 455 on the front squat. I also deadlift without any problems. I tried olympic cleaning for a couple of months, but that caused my knee to swell. That's my experience any way: squat and deadlift without an ACL, but don't do Olympic lifts. Two tips that helped me were:

  1. keep all the weight on my heels at all times
  2. squat very frequently, every day if possible and at least every other day.

That really seamed to maintain the range of motion and keep the stroke efficient and safe so that when I fail on a set it's because my hams/glutes are spent and not because I'm shifting my weight oddly to baby my involved leg.


I am an active duty Marine and following an injury and MRI that revealed a completely torn ACL, torn MCL, and bilateral miniscal tear, I was back to working out my leg within roughly 2 months. By the way, I was in Afghanistan 3.5 weeks following the tear. It was a slow process and incremental in nature, but effective. To the root of your question though, yes, you can squat and deadlift. You know your body though and that is key. However, I was doing squats and repping 225lbs within 3-4 months, leg extensions(!), deadlifts, and eventually graduated to box jumps and box over jumps within a year (crossfit) after getting home. I just got surgery Oct 11th and I'll be damned, I am doing it all over again. There lies the irony... Good Luck.


I squat and deadlift 600 pounds 10 years after a failed ACL reconstruction. I experience minimal issues while weight lifting heavy 3-5 days/week. (The lack of the ACL never causes me problems. My knee's stable during the exercises. But my failed surgery was a patellar autograft. The graft harvest caused my patella to move, and the poor patellar tracking that resulted causes mild swelling with any strenuous activity.)

Incidentally... my surgeon recommended against squatting and deadlifting. I babied the knee for years and started developing arthritis around the patella. I got to the point where it was hard to stand up, and I started light weightlifting to try to recover. The more frequently I lifted the better the knee got. Today my involved leg is stronger and has a slightly better range of motion than my non-involved leg. Aside from the patellar tracking issue that happened because of the surgery, the leg doesn't give me any trouble. I play basketball with my kids and can dunk a tennis ball.

  • That's awesome! I just had my surgery done 5 months ago. I've been air squatting, no waits and it has built up my leg strength. Though these days my leg constantly swollen, I'm going to go see a Dr on how to get rid of this...
    – user772401
    Sep 11 '12 at 12:53
  • Forgot to post the comment in time, anyway: I edited your post, I don't think that namecalling adds any value to your answer. In fact I think it might be considered defaming. If you are unhappy with the changes feel free to revert or edit again.
    – Baarn
    Sep 25 '12 at 13:58

I don't think Squats and Dead Lifts are the type of exercises your doctor had in mind when he suggested you strengthen your leg muscles before your surgery.

Perhaps light leg extensions or leg press would be better suited to someone with an injury. I'd suggest light weight and high (20+) reps.

Squats and Dead Lifts could be done with light weights, but unless you really know what you are doing with those exercises (that is, you have been doing those exercises for years), I would not advise starting them in your current physical state.

  • 4
    Leg extensions don't activate the hamstrings at all, do not allow them to assist in stability of the tibia at the knee, and actually place more stress on the ACL than either squats or leg presses. It's widely agreed that people recovering from ACL injuries should avoid leg extensions. However, the squat and leg press put very little stress on the ACL when done with proper form. The squat is preferred because of higher hamstring activation, due to the wider stance. The leg press is fine, it just will use more quads than hams, as would a narrow-stance squat.
    – user2567
    Jan 14 '12 at 0:51

I tore my ACL training for a MMA tournament. Had total ACL reconstruction using a cadaver and arthroscopic surgery to scrape calcium deposits off my knee cap( doc said 9 months before I could do any cutting movements etc)
I did intense rehab and stretching for three months, gradually went to the leg press high foot placement and increasingly heavy loads.
I then began box jumping on a low box about 20 inches many times smaller for lateral jumps.
I jumped rope and did lots and lots and lots of lunges.
I also quit leg extensions as the put unnatural tension on your ACL and patella tendon.

By April 2011 ( August surgery) I was jogging up two 2 and 1.5 miles a day. I continued basic pt movements , leg press and lunges then in January of this year I did my first deadlift in over 2 yrs.
I also began weighted back squats. My knee feels better than ever, I tweaked it yesterday landing odd on a high box while doing seated box jumps, but I'm fine just had some fluid on it the next day.
So my rehab was basically insane amounts of pt movements always using resistance bands, Jump rope, squats using body weight, jogging and lunges brought me back from the dead. Now I am squatting 500 and deadlifting 520. I only box squat now because its safer and strengthens the posterior chain and upper quads/ hip fleckers which is way more important than lower quad development. I do sled pulls the strengthen quads and lunges/ reverse lunges. Step ups with moderate weight also helps tremendously.

The only reason I still bust my ass is because I am finishing my masters in Sports Science and opening my own athletic training facility/ power lifting club since their are none in my town. I admit my squat was once 800 lbs and my dead was once about 750. I don't care if I can ever lift that again, but in order to train others I need to at least perfect my lifts. I put 20 lbs back on my deads and squats after switching to the conjugate system march of this year. I plan to be back to 800 dl and sq but if I don't make it its no big deal.

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