Return to Running after ACL surgery

 In Exercise and Health

ACL Surgery

“When can I run again?” – it’s a common question that’s fielded following an ACL-reconstruction surgery. There is no cut and dry answer to this. Recommencing running is often an important physical and mental hurdle following surgery as it signifies a large step towards a return to sporting activities. Often the 12 week mark is suggested as an appropriate time to commence running however it’s probable that return to running (RTR) should be based on performance based criteria rather than a generic time frame (1).

Why Time?

Time since surgery is an important factor. Significant healing of the graft occurs in the first 12 weeks and the importance of this can’t be discounted. From 4 to 12 weeks post-op is known as the proliferation phase where there is maximum cellular activity but also the lowest mechanical properties of the new ligament (5). This means a lot of healing is occurring but the graft is also weak. During the first 8 weeks, the bone is also attempting to heal and attach the graft to the bone inside the tunnel. Excessive motion in this period may impair healing, however controlled loading is beneficial (4). Whilst time is important, it does not take into account the individual’s physical or mental readiness to recommence running.

The 3 main ACL-R surgical procedures with varying harvest sites and graft techniques. This displays the tunnel drilled through the tibia and femur to locate the reconstructed ligament. A. shows a bone-patella tendon-bone graft, B. is a hamstring graft technique, C. is a hamstring and gracillis muscle graft.

Performance Based Criteria

In 2018, a scoping review study was published showing that less than 1 in 5 ACL-reconstruction studies used clinical, strength or performance based criteria to clear patients to return to run. This means over 80% were relying on time from surgery as the determinant for recommencing running (1). “So what?” I hear you say, what is the importance of using such criteria. We now know from the available evidence that people who return to sport too soon or when they are not physically or mentally ready, have a much greater chance of re-rupturing their ACL. A 2016 study found that those who returned to sport without passing a battery of 6 performance-based tests were 4-times more likely to rupture their ACL graft (2).

Clinical, strength and performance milestones are important measures to gauge the capacity of the knee to deal with activities of daily living before progressing into higher demand activities. This approach takes into account the individuals personal progress as opposed to a one-size-fits-all model. It also provides clinicians a clearer, evidence based and more robust roadmap for return to running. Patients should feel confident their therapist is progressing their rehabilitation based on defined milestones and not guessing. When the patient cannot achieve functional tasks without symptoms (increase in pain, effusion and ROM restrictions) such as following walking or rehab exercise, this suggests inferior load management. This would suggest that delaying RTR is appropriate, irrespective of the postoperative time (1).

The three elements of the return to sport (RTS) continuum from Ardern et. al. in the specific context of ACL reconstruction.

Is it safe to run?

When implemented correctly, running has been shown to be safe and well-tolerated following ACL reconstructive surgery. Using both clinical and instrumental assessments, research has found that a running protocol including both interval and speed work implemented at 4 months post-op did not increase ligament laxity. Interestingly, this research also discovered that running alone was not enough to improve strength in the knee flexors or extensors post-op (3). This means specific strength training is required.

So when can you run?

By best available evidence, it is likely you can expect to recommence running between the 8th to 16th week post-surgery depending on the rehabilitation plan (1). Based on the best current evidence, the large 2018 review suggested the following criteria should bed passed in order to begin running:

Further performance based criteria suggested by Mick Hughes, physiotherapist and co-author of the Melbourne ACL Rehabilitation Guide, include >85% LSI for the following exercises (6):

  • 5 single-leg squats off a 20cm box (ensuring good quality of movement)
  • 10 single-leg rises from 90° knee bend
  • 20 single-leg hamstring bridges
  • 30 second side bridge
  • 20 single-leg heel raises
  • 45 seconds single-leg balance on affected leg

In summary, clinicians are moving away from time-based criteria for a return to running and making this decision based on a performance criteria. Currently it is not perfect although it is more individualised and objective than relying on post-operative time frames.

Key Points

  • There is a gap in the scientific literature for RTR criteria following ACL-R
  • In over 200 studies, only 1 in 5 used a performance based criteria for RTR
  • Time-based criteria is most commonly used with 12 weeks the most common time to commence RTR
  • Time does not take into account an individual’s needs
  • Defined performance criteria need more research but there have been some suggested for improved patient outcomes
  • Running has been shown to be safe and not increase laxity in the graft



Listen to Mick Hughes on The Physical Performance Show discussing all things ACL rehabilitation


James Gardiner
POGO Physiotherapist

Book an Appointment with James here.

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  1. Rambaud, A. J., Ardern, C. L., Thoreux, P., Regnaux, J., & Edouard, P. (2018). Criteria for return to running after anterior cruciate ligament reconstruction: A scoping review. British Journal of Sports Medicine, 52(22)
  2. Kyritsis, P., Bahr, R., Landreau, P., Miladi, R., & Witvrouw, E. (2016). Likelihood of ACL Graft rupture: Not meeting six clinical discharge criteria before return to sport is associated with a four times greater risk of rupture. British Journal of Sports Medicine, 50(15)
  3. Dauty, M., Menu, P., & Dubois, C. (2010). Effects of running retraining after knee anterior cruciate ligament reconstruction. Annals of Physical and Rehabilitation Medicine, 53(3)
  4. Muller, B., Bowman, K. F., & Bedi, A. (2013). ACL Graft Healing and Biologics. Clinics in Sports Medicine, 32(1)
  5. Scheffler, S. U., Unterhauser, F. N., & Weiler, A. (2008). Graft remodeling and ligamentization after cruciate ligament reconstruction. Knee Surgery, Sports Traumatology, Arthroscopy, 16(9)
  6. Hughes, M. (2018, July 25). Return to Running Following ACL Reconstruction [Video]. YouTube.

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