Should I Run 4 Months After ACL Surgery?

Should I Run 4 Months After ACL Surgery?


Running after ACL surgery is a big milestone in every rehab process. It shows progress, it helps you feel like an athlete and it is one more step in getting ready to play your sport. Commonly, in time based rehab protocols, the four month mark is when an athlete is cleared to start running. But are you really ready after four months to start running after ACL surgery?

Truthfully, it depends. Rather than just starting a running progression at four months because a protocol on a piece of paper tells you to, you should go through an objective testing protocol to determine your readiness to run. 

Use Objective Testing Protocols

Since we as a physical therapy clinic have transitioned to this objective testing protocol (rather than just starting to run after a period of time), we have seen dramatically better results:

  • Less knee pain with running
  • Less knee swelling
  • Less time spent working on “improving” your running gait
  • Faster progression through a return to running program

So, how do you know you are ready to start running after ACL surgery? Here’s the five objective tests we want to look at:

1. How many single leg squats can you do? 

Running requires good single leg control with adequate quadricep strength and hip strength to support your body weight and minimize any compensations.  

What else requires good single leg control with hip and quad strength? Single leg squats.

We recommend being able to perform at least 25 single leg squats with good technique to ~90 degrees of knee bending on both legs before starting to run. This is a basic strength and endurance test to see where your single leg control is at.

Our clinic record right now is 96 single leg squats by a recovering ACLer. Think you can beat it?

2. How many single leg heel raises (calf raises) can you do?

The calf and achilles complex is key to proper running form. It also helps you to control bending your knee. If you haven’t recovered enough calf strength before running, it will lead to compensations or increased stress on your knee. Either of these can lead to more injuries or a reinjury of the ACL.

We want to see you perform at least 25 single leg heel raises with your heel getting equally high on both legs. We also want to see you perform them quickly, at about 1 heel raise/second. Using a metronome can help you stay on pace.

3. Can you tolerate impact?

There are roughly 5,000 foot contacts in a mile of running. This means there are about 5,000 small impacts with the ground over and over again within that one mile. So, before you start running after ACL surgery, we want to make sure your knee is ready to tolerate that many ground contacts.

We like using a single leg pogo test. These are quick, small jumps off of the ground using one leg as fast as you can. We want to do this for a specified time and see you be able to maintain your speed with no pain for 30 seconds on each leg.

Count how many hops you can complete in 30 seconds and compare side to side. Your surgical leg should be within at least 10% of your other leg before starting a running program. Additionally, make sure you don’t have knee pain or knee swelling following this test. 

4. Have 70% of your quad strength back

If I sound like a broken record, I apologize, but your quadriceps strength matters in ACL rehab… a lot

It is typically the biggest deficit we see, and it takes time and hard work to recover what was lost while your knee was out of commission.  

Your quad is like a shock absorber for your knee. If you don’t have at least 70% of your quad strength recovered, you will run with a peg leg on the injured side and with very hard, slamming foot contacts with the ground. This creates a lot of stress, pain and often swelling on the injured knee.

While the single leg squat and pogo test are a good proxy, nothing substitutes for actually measuring your quad strength.  Unfortunately, you can’t do this on your own and do need equipment.  However, any physical therapist that specializes in ACL rehab in athletes should have a way to measure your quad strength. 

At Kinetic Sports Medicine & Performance, we have different packages for Post-Op ACL Rehab Testing, depending where you are at in your rehab process. See which one is right for you or ask us more about it

5. Perform a progressive rehabilitation program

Rehab should not be like a lightswitch, where one day you can’t run and then suddenly the next day you can just because the calendar day changed.

You want to take baby steps that are building up towards running. This should include a slow, two-footed impact progression and often some pre-running drills like an A-March, A-Skip and potentially high knee run

By taking these baby steps in your rehabilitation program, the jump to running is typically smooth with minimal complications. 

Running after ACL surgery is a huge milestone and it should be celebrated! But it shouldn’t be rushed, and you should not start to run just because you are 4 months out from surgery.  Follow these five steps we gave above and you’ll have a smooth return-to-running!

If you would like to learn more about what you should be doing at each stage of your ACL rehab and what goals you need to hit to keep progressing, check out our FREE online mini-course Guide to ACL Rehab: What you need to know from time of surgery to return-to-play.

At Kinetic Sports Medicine and Performance, we specialize in working with athletes recovering from ACL rehab. We have supported professional athletes, college players, high schoolers and weekend warriors as they recover and return to performance. Check out our ACL Rehab page to learn more and schedule a free consultation.

Read more on ACL rehab:

What to do before ACL surgery?

How Do I Return Back to Sport After an ACL Injury

ACL Rehab Exercises: Why Knee Extension are Essential

Or listen to our other ACL topics:

Early Stage ACL Rehab Do’s and Don’ts

ACL Return-to-Play