ACLR & Returning to Running

ACLR: “When Can I Run Again?”

Physical therapists are often asked “when can I run again?” after an ACL injury or surgery. The honest answer is “it depends”. There are many factors that impact when we can provide an accurate answer to that question. Each individual is dealing with unique circumstances specific to their own recovery. Therefore, it is very hard to generalize a set of criteria to the whole population. In this blog I want to highlight the criteria recommended to clear a patient to return to running or jogging after ACLR. At Symmetry, we help our patients with recovery both pre and post ACL surgery. 


Time may be the most predictive factor when it comes to protecting the graft and decreasing risk of re-injury. Research suggests that athletes may enter a progressive return to running (RTR) program as early as 10 weeks. Most protocols suggest waiting until at least 12 weeks post-op before initiating a RTR program. Some surgeons recommend waiting until 16 weeks if they are concerned about protecting the graft. Rambaud et al performed a thorough review of ACL protocols which determined that 12 weeks is the average recommended time to wait. Time is not the only determining factor to receive clearance to run again after ACLR. However, it is helpful to ensure proper healing, remodeling, and maturation of the tissue has occurred. 

Range of Motion

It is important to restore full knee extension within the first 1-2 weeks after surgery. This helps to reduce the risk of arthrofibrosis and scar tissue development. Full knee extension is important to improve functional capacity of the knee. This will help normalize gait and motor unit activation of the quadriceps muscles. Restoration of full knee flexion within 95% of the contralateral side is recommended within the first 4-6 weeks post-op.

Full knee ROM will help to reduce the risk of developing arthritis in the knee later in life. It is crucial to regain full ROM prior to progressing into the next phase of post-op protocol. We typically use a subjective scale to ask our patients to rate their pain on a scale of 0-10. It’s recommended that patients are cleared to begin running when their pain levels are minimal (<2/10). 


The gold standard of strength testing is isokinetic testing. However, there are many alternative strength measurements that are used in the clinic that may be more practical. We typically use isometric manual muscle testing techniques in combination with functional testing. This determines strength and functional capacity. We are looking for at least 70% strength of quadriceps and hamstrings. This is compared to the opposite leg during strength testing to allow for safe initiation of running.

Strengthening will continue during the months after a patient begins to run again. Before an athlete is cleared to return to sport we would want to have at least 90% strength of the non-surgical leg . Ideally, you wouldn’t stop at 90%. Instead, you would strive to have symmetrical strength prior to returning to sport. 


Normalized Gait and Squat Patterns

Abnormal gait mechanics, such as limping, are indicators that the athlete will not be able to tolerate the forces of running. Patients have to demonstrate that they are able to walk before they can run. Squat form is another movement we assess to identify impairments in strength, balance, and trust in the surgical limb. Patients need to be able to demonstrate the ability to squat with good limb symmetry. This should be done prior to being cleared to initiate running. 

Multidirectional Single Limb Stability

Single limb stability is essential to perform a dynamic single leg exercise such as running. Utilizing a star excursion or Y-balance test will assess single leg stability in multiple directions. This determine if the surgical leg is stable enough to tolerate the forces of running. Patients need to demonstrate that their composite Y-balance test score is at least 90% of the non-surgical limb.

ACLR & Functional Testing

Examples of functional strength testing are: Step Downs, Single Leg Squats, Step Up and Hold. These can be used to determine if it is appropriate to initiate a running program. Rambaud et al recommends that a patient should be able to perform at least 10 consecutive single limb squats to 45 degrees knee flexion without loss of balance or dynamic knee valgus. I typically look for a patient to be able to perform squat to greater depth (90 degrees). All of these tests are evaluating adequate strength and stability to perform a single limb closed-kinetic-chain exercise.  Tests ensure that the athlete is prepared for the loads of running. 


Hop Testing

Single Limb Hop for Distance, Triple Hop, Crossover Triple Hop, and Timed 6m Hop are the most commonly used measures to determine return to sport in post-op ACLR patients. An athlete has to achieve at least 90% limb symmetry during each hop test prior to returning to sport. Clinical judgement needs to be taken on a case-by-case basis. We need to assess movement patterns, eccentric control, and shock absorption. 

hop test

Hop testing can be utilized to determine power, strength, stability, agility, speed, eccentric control, and shock absorption, but it is only a piece of the puzzle in the decision-making process to determine appropriate clearance to return to sport. Typically we are looking for at least 70% limb symmetry with good shock absorption and dynamic single limb stability on the landing to clear an athlete to begin RTR program. I recommend that patients need to be able to stick the landing for at least 3 seconds for the hop to be acceptable. 


Post-Activity Swelling

Another objective measure to consider during ACLR is joint effusion after increased activity. It is normal to have mild swelling after activity in post-op patients, but we are looking for that swelling to remain for less than 24 hours after exercise. This is an indication that the tissues are healing well and that we are not progressing the loads too quickly. 

There are many factors to consider when determining that you are ready to run after your surgery.  Each one of these objective measures are prerequisites to running and can be viewed as short-term goals that need to be accomplished prior to the initiation of running activities. 

Checklist to Return to Running (RTR) after ACLR

  1. Time: 12 weeks
  2. At least 95% knee flexion and full knee extension ROM compared to contralateral side
  3. Strength: at least 70% quadriceps/hamstrings strength compared to contralateral side
  4. Pain: < 2/10
  5. Normalized gait pattern and squat mechanics
  6. Y-balance Test: at least >90% composite score compared to contralateral side
  7. Functional Testing
    1. SL Squats: at least 10 repetitions to at least 90 degrees of knee flexion without loss of balance or dynamic knee valgus
    2. Step Up and Hold: 30 consecutive repetitions without loss of balance or excessive motion outside of sagittal plane
    3. Step Down Test: perform at least 10 consecutive repetitions of anterior step downs on 8 inch box (without dynamic knee valgus and good single limb stability symmetrical to contralateral side)
  8. Hop Testing: at least >70% LSI and good shock attenuation/eccentric control without dynamic knee valgus
  9. No joint effusion: no post-activity swelling for 24 hours after exercise

We can help you in your ACLR journey either in clinic or virtually! Team Symmetry is on your side. 


Written By: Dr. Timothy Alemi, PT, DPT, SCS

Rambaud AJM, Ardern CL, Thoreux P, et al, Criteria for return to running after anterior cruciate ligament reconstruction: a scoping review, British Journal of Sports Medicine 2018;52:1437-1444.

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