An anterior cruciate ligament (ACL) injury can feel overwhelming. One minute you are skiing with your family or jumping up to grab a rebound, and the next minute you are hearing the echoes of that classic “pop” and wondering how you will ever get back to the activities you love. Many people are forced to wait months, or even years, for ACL reconstruction surgery due to issues with access to quality healthcare. Others have surgery almost right away, without preparing their knee for surgery and long post-operative rehab afterward. In almost all cases, it is wise to take a month or two to prepare your knee for ACL reconstruction surgery. This article will take a look at the exercises prior to an ACL surgery that will put you in a position for the best possible outcome post-operation!


What happens after an ACL injury?

When an ACL tear happens, the first response of your knee is to swell. This swelling occurs deep inside your knee joint, which is surrounded by a capsule and is thus known as joint effusion. Interested in learning more about tissue healing? Read this article.


Joint effusion has a number of effects, one of the worst being decreasing the strength and firing rate of your quadriceps. We can think of this as “shutting off” your quadriceps as the nerves that help your quad muscles to fire are inhibited due to both the trauma of the injury and the subsequent joint effusion.


In most cases, the knee will also lose range of motion. Effusion plays a role in this, as the fluid inside the capsule takes up the limited space for your joint to move. Additionally, the natural reaction of your body after a trauma such as an ACL tear is to tighten up and guard movement, thus many of the surrounding muscles inhibit both the bending and straightening of the knee after this injury. Dealing with limited range of motion of the knee? Read this article!


improving knee flexion acl prehab exercises the prehab guys


The combination of swelling, decreased quad strength, decreased range of motion, and pain (which may or may not be present) all contribute to affecting the normal walking pattern. While all of these factors contribute to altering gait mechanics, they can also be made worse by a change in your walking pattern, thus it can be a vicious cycle. For this reason, crutches are often recommended after an ACL injury to help re-establish a normalized gait.


Engage In A Full Knee Prehab Program To Maximize Your ACL Outcomes!

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This program is designed to put you in a position for the best possible outcome post-operation! You can use it for ACL prehab and ACL rehab after! Get started today by clicking HERE!


So, what are the goals after an ACL injury?

A 2016 study showed significantly improved outcomes 2 years after ACL reconstruction surgery in a group who underwent pre-operative rehabilitation as compared to a group receiving similar post-operative rehabilitation only.  These improved outcomes included both returning to pre-injury level of sports as well as patient-reported outcomes measures of knee function.


This successful group sought to achieve the following goals:


Goal 1: Establish a “quiet knee”.

This means focusing on reducing joint effusion. While we have gone away from over-using ice for many acute injuries, it still has its place and helps to reduce the swelling in the first couple of days after an acute ACL tear. This is one of those times that ice and elevation can be beneficial. But more importantly, starting to move in a comfortable range of motion will have the best benefits for reducing joint effusion.


Goal 2: Restore full range of motion.

Most importantly this includes restoring a straight or fully extended knee that is on par with your non-injured knee. Thus, if your knee was able to achieve hyperextension prior to this injury, you should be actively working to restore that range of motion. Additionally, gradual progression of knee bending or flexion range of motion is critical to a successful outcome after ACL surgery. In both of these cases, range of motion gains is best achieved in small consistent doses throughout the day.


Want to learn more about ACL’s?  


Goal 3: Re-establish quad strength & firing capacity.

This starts with your basic focus on activating your quad muscle purposefully through exercises like quad sets. However, as your pain tolerance allows, this should very quickly include progressively resisted knee extension exercises in both an open and closed chain fashion. The only way to re-establish proper firing of all the motor units of your quadriceps is to appropriately challenge them with high levels of resistance.

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So what are the best exercises prior to ACL surgery?

Research has established that a short-term progressive exercise program aimed at the above-listed goals is both well tolerated and can lead to improvements in both short and long-term outcomes after ACL surgery. While there are many exercises that can help achieve these goals, the following list is a few that this author has found to be most helpful in achieving these desired outcomes prior to ACL surgery.


Seated Knee Flexion AAROM, Strap

Sample Knee [P]rehab Program Exercise Video

The heel slide exercise is an excellent way of passively restoring flexion range of motion. When performed consistently and gently throughout the day, this will not only help restore flexion range of motion but also help decrease joint effusion. This exercise can be started on the day of an ACL injury.


Seated Knee Extension – PROM

While shown here as an exercise, this is best used as a resting position after an ACL injury. Restoring full extension range of motion is so important and the best way to do that is with low load long duration stretching that includes propping your heel up and allowing gravity to bring your knee into an extended position.


Quad set

The quad set exercise is great for helping to re-establish purposeful or volitional contraction of the quadriceps. This helps to rebuild the neuromuscular connections between your brain and your quadriceps that are inhibited after an ACL injury. Focusing on trying to lift your heel while digging your knee into the towel will also help improve control of hyperextension range of motion.


The following exercises may not be able to be performed right away but should be included as early as possible in a robust pre-operative ACL program.


Stagger Stance Box Squat

This is an excellent exercise for utilizing your quadriceps in a functional, closed chain capacity. You may need to perform this in a smaller range of motion by using a higher box or chair, but beginning to utilize your quad and glutes will help to rebuild muscle and decrease swelling.


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Single Leg – Knee Extension

The single-leg knee extension machine is the best way to progressively overload your quadriceps and restore the loss of quad strength that occurs after an ACL injury. It is a must!


Single Leg – Leg Press

While the single-leg leg press does not isolate your quadriceps quite as well as the knee extension machine does, it is still excellent for rebuilding quad strength and controlling closed chain knee extension! Definitely one of the great exercises before ACL surgery.


Closing Thoughts

The road to a successful outcome after ACL surgery starts the day you suffer an ACL injury. Progressively resisted exercises focusing on building quad strength, restoring range of motion, and decreasing joint effusion to establish a “quiet knee” can improve the results of your ACL surgery in both the short and long term! The exercises listed above are the ones that this author has found to be most critical in the pre-operative phase to prepare for a successful post-operative ACL rehab!


Engage In A Full Knee Prehab Program To Maximize Your ACL Outcomes!

knee prehab program exercises prior to acl surgery prehab guys

This program is designed to put you in a position for the best possible outcome post-operation! You can use it for ACL prehab and ACL rehab after! Get started today by clicking HERE!



  1. Shaarani SR, O’Hare C, Quinn A, Moyna N, Moran R, O’Byrne JM. Effect of Prehabilitation on the Outcome of Anterior Cruciate Ligament Reconstruction. The American Journal of Sports Medicine. 2013;41(9):2117-2127. doi:10.1177/0363546513493594
  2. Failla MJ, Logerstedt DS, Grindem H, et al. Does Extended Preoperative Rehabilitation Influence Outcomes 2 Years After ACL Reconstruction? A Comparative Effectiveness Study Between the MOON and Delaware-Oslo ACL Cohorts [published correction appears in Am J Sports Med. 2017 Apr;45(5):NP9]. Am J Sports Med. 2016;44(10):2608-2614. doi:10.1177/0363546516652594
  3. Grindem H, Granan LP, Risberg MA, Engebretsen L, Snyder-Mackler L, Eitzen I. How does a combined preoperative and postoperative rehabilitation programme influence the outcome of ACL reconstruction 2 years after surgery? A comparison between patients in the Delaware-Oslo ACL Cohort and the Norwegian National Knee Ligament Registry. Br J Sports Med. 2015;49(6):385-389. doi:10.1136/bjsports-2014-093891
  4. Eitzen I, Moksnes H, Snyder-Mackler L, Risberg MA. A progressive 5-week exercise therapy program leads to significant improvement in knee function early after anterior cruciate ligament injury. J Orthop Sports Phys Ther. 2010;40(11):705-721. doi:10.2519/jospt.2010.3345
  5. Eitzen I, Holm I, Risberg MA. Preoperative quadriceps strength is a significant predictor of knee function two years after anterior cruciate ligament reconstruction. Br J Sports Med. 2009;43(5):371-376. doi:10.1136/bjsm.2008.057059


About The Author

Tommy Mandala, PT, DPT, OCS, SCS, CSCS

[P]rehab Writer & Content Creator

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Tommy Mandala is a Doctor of Physical Therapy, Board Certified Clinical Specialist in Sports & Orthopedics, and Certified Strength and Conditioning Specialist in New York City. He is the founder of ALL IN ACL, a digital coaching platform dedicated exclusively to helping ACLers return to the life they had before their injury with full confidence in their knee. Prior to that, he worked in the sports clinic at Hospital for Special Surgery, the #1 Orthopedic Hospital in the country. While there, he had the opportunity to hone his skills as an ACL specialist working closely with world renowned surgeons and evaluating patients from all over the world. He completed his sports residency training at the University of Delaware where he had opportunities to work with many of their Division I sports teams as well as the Philadelphia 76’ers NBA G-league affiliate, the Delaware Blue Coats. He also trained at Champion Sports Medicine in Birmingham, Alabama where he had the opportunity to learn from researchers in the American Sports Medicine Institute. Currently, Tommy works exclusively with ACLers through his digital coaching model. While many of these clients are athletes, Tommy works with ACLers of all different abilities helping them to build the strength they need to overcome this unique injury. One of his favorite aspects of his job is taking active clients who have never been a “gym person” before and showing them the amazing things that happen when they learn to strength train.






Disclaimer – The content here is designed for information & education purposes only and is not intended for medical advice.

About the author : Tommy Mandala PT, DPT, SCS, OCS, CSCS

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  1. Michael Lau August 25, 2021 at 9:01 am


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