If you’ve had an ACL reconstruction, there’s a good chance you’ve already asked the question:
When can I start running again?
For many people, getting back to running is one of the most exciting milestones in ACL rehabilitation. After months of rebuilding strength, restoring movement and working through seemingly endless rehab exercises, it’s often the first time you start to feel like an athlete again.
Most people begin working towards running around 12 weeks after ACL surgery, but the timeline alone doesn’t determine whether you’re ready. Your knee needs sufficient strength, movement and tolerance to impact before you start. Some people reach these milestones earlier than others, while some need considerably longer. Neither automatically means your recovery is going well or poorly.
So, what actually determines when you can run again?
Why Can’t You Run Straight Away After ACL Surgery?
ACL reconstruction involves replacing your injured anterior cruciate ligament with a graft, commonly taken from your hamstring, patellar tendon or quadriceps tendon. Following surgery, your body needs time to recover, and the graft undergoes a gradual process of biological healing and adaptation. But healing is only part of the picture.
Your quadriceps, hamstrings and other muscles around the knee also need to regain their strength and ability to manage load. This matters because running places repeated demands on your legs. Each stride involves landing on one leg, absorbing force and pushing yourself forwards.
Although running might feel relatively straightforward before an injury, it requires considerably more strength and coordination than walking. If your knee isn’t ready to tolerate these demands, you may experience increased pain, swelling or difficulty controlling your movement.
That’s why returning to running should be treated as a rehabilitation milestone rather than something you automatically start once enough time has passed.
How Long After ACL Surgery Can You Start Running?
Traditionally, the 12-week mark has been used as a guide for returning to running after ACL reconstruction.
A large review of ACL rehabilitation research found that 12 weeks was the most commonly reported timeframe for beginning running. However, fewer than 20% of the studies included additional clinical or physical performance criteria when making this decision.
More recent clinical guidelines recommend combining time since surgery with assessments of knee function, strength and impact tolerance. In practical terms, this means two people who underwent ACL surgery on the same day might be ready to run at completely different times.
One person might have regained excellent quadriceps strength, full knee movement and the ability to tolerate hopping exercises by three months. Another might still be experiencing swelling, reduced strength or difficulty controlling single-leg movements.
Even though they’ve reached the same point on the calendar, their knees aren’t necessarily ready for the same activities. The goal isn’t to start running as early as possible. It’s to start running when your knee is prepared for it.
Your surgeon’s recommendations also matter, particularly if your reconstruction involved additional procedures such as a meniscus repair.
How Do You Know If You’re Ready to Run After ACL Surgery?
Before returning to running, your physiotherapist should assess several important aspects of your recovery. These help determine whether your knee can tolerate the repetitive impact and loading involved in running.
1. Your Knee Has Regained Its Movement
Before running, you should be able to fully straighten your knee and have regained almost all of your knee-bending range. The 2023 Aspetar ACL rehabilitation guidelines recommend full knee extension and at least 95% of your knee flexion range compared with your other leg.
This matters because restrictions in knee movement can affect how you walk, run and absorb force. If you’re still struggling to straighten your knee or experiencing significant stiffness, restoring your movement should remain a priority.
2. You Have Minimal Pain and Swelling
Your knee should be relatively settled before introducing running. That means little to no swelling and no significant pain during everyday activities or rehabilitation exercises. Swelling is particularly important because it can affect quadriceps activation and your ability to generate force.
If your knee regularly becomes swollen after walking, gym exercises or other activities, it may not yet be tolerating your current training load. Adding running on top of that could make managing your symptoms more difficult.
A knee that feels good during exercise but becomes noticeably swollen later that evening or the following morning is also worth paying attention to.
3. You’ve Regained Enough Quadriceps Strength
Your quadriceps are particularly important when returning to running. These are the large muscles at the front of your thigh, responsible for helping straighten your knee and controlling the forces involved when your foot contacts the ground.
Following ACL surgery, quadriceps weakness is common and can persist well beyond the early stages of rehabilitation. Current expert recommendations suggest achieving greater than 80% quadriceps strength symmetry before returning to running.
What does 80% strength symmetry actually mean?
Imagine your uninjured leg produces 100 units of force during a strength test. Your operated leg would need to produce more than 80 units to achieve the recommended level of symmetry.
This is commonly measured using specialised strength-testing equipment. However, there’s an important catch. If your uninjured leg has also become weaker during rehabilitation, achieving 80% symmetry doesn’t necessarily mean you’ve regained enough overall strength.
That’s why assessing your actual strength, rather than simply comparing one leg with the other, can provide a more complete picture.
4. You Can Tolerate Hopping and Landing
Running is essentially a series of small, repeated single-leg landings. Before introducing continuous running, it’s important to demonstrate that your knee can tolerate some of these demands in a controlled environment.
Your rehabilitation might include exercises such as:
- Double-leg hopping and landing drills.
- Repeated small single-leg hops, sometimes called pogos.
- Controlled jumping and landing exercises.
- Progressive single-leg strength exercises.
Your physiotherapist may also assess how effectively you absorb force when landing. For example, someone might be able to perform a single-leg hop but consistently land with a stiff knee or shift their weight away from their operated leg.
These movement patterns can help identify areas that still need attention. The Aspetar guidelines include pain-free repeated single-leg hopping and objective jump-performance measures among their proposed return-to-running criteria.
Not everyone will have access to advanced testing equipment, but a combination of strength testing, functional exercises and clinical assessment can help guide the decision.
What Does Your First Run After ACL Surgery Look Like?
Your first run after ACL reconstruction probably won’t look like the runs you were doing before your injury. And that’s completely fine.
Rather than heading out for a continuous 5 km run, most people benefit from starting with short intervals of jogging separated by walking. This allows you to gradually introduce running loads while monitoring how your knee responds.
For example, an introductory session might involve alternating:
1 minute of easy jogging with 2 minutes of walking, repeated several times.
This is only an example, not a universal starting prescription. The appropriate duration, number of repetitions and running speed should depend on your assessment and rehabilitation progress.
Initially, running on a flat, predictable surface at a comfortable pace is generally a sensible place to start. Your first few sessions should focus on controlled movement and building tolerance rather than speed or distance.
How Quickly Should You Progress?
Once you’ve started running, the next challenge is gradually increasing how much your knee can tolerate. This might involve progressing from short jogging intervals towards longer periods of continuous running.
However, it’s important to consider how your knee responds both during and after each session. Some useful questions include:
- Did you experience pain while running?
- Did your knee become swollen afterwards?
- Were you able to maintain a comfortable running pattern?
- Did your knee feel significantly worse the following morning?
If your knee is tolerating the sessions well, your running programme can gradually progress. If symptoms increase or your movement deteriorates, you may need to reduce the load or spend more time developing strength and impact tolerance. There isn’t one progression rate that works for everyone.
What If Your Knee Hurts When You Start Running?
Experiencing some discomfort when introducing a new activity doesn’t automatically mean you’ve damaged your ACL graft. Your knee is adapting to demands it may not have experienced for several months. However, pain shouldn’t simply be ignored.
The location, intensity and behaviour of your symptoms can provide useful information about how your knee is responding. For example, mild discomfort that settles quickly and doesn’t result in swelling may be managed differently from sharp pain, increasing swelling or a feeling that your knee is giving way.
If you experience persistent pain, recurrent swelling or instability, it’s worth having your knee reassessed before progressing. Your physiotherapist can help determine whether your symptoms are related to training load, strength deficits, movement limitations or something that requires further medical review.
What If You’re Not Ready to Run at 12 Weeks?
If you’ve reached three months after surgery and you’re still not ready to run, it doesn’t mean you’ve failed your rehabilitation. ACL recovery isn’t always linear. Some people regain their strength and movement relatively quickly, while others need more time.
Factors such as your pre-surgery strength, the type of graft used, additional knee injuries and your individual recovery can all influence your progress. Instead of focusing entirely on how many weeks have passed, it’s more useful to identify what’s currently holding you back.
For example, if your quadriceps strength is still significantly reduced, your rehabilitation might place greater emphasis on progressive strength training. If you’re strong but struggling with hopping and landing, you may need more time developing your ability to tolerate and control impact.
Having clear, measurable goals can make this stage of rehabilitation much less frustrating. It gives you something meaningful to work towards rather than simply waiting for another few weeks to pass.
Does Running Mean You’re Ready to Return to Sport?
Not quite. Returning to running is an important milestone, but it’s only one part of the ACL rehabilitation process. Straight-line jogging is very different from the demands of sports like football, netball, basketball or rugby.
These activities involve sprinting, sudden changes of direction, deceleration, jumping, landing and reacting to other players. Each places different demands on your knee. Even if you’re running comfortably, you may still need considerable improvements in strength, power, agility and confidence before returning to unrestricted sport.
That’s why ACL rehabilitation should continue well beyond your first successful run. The aim is to progressively rebuild the physical qualities required for the activities you want to return to, rather than treating running as the finish line.
Getting Back to Running After ACL Surgery in Brisbane
At SportsPlus Physiotherapy in Highgate Hill, Brisbane, our physiotherapists and exercise physiologists help people work through the different stages of ACL rehabilitation.
From rebuilding strength and restoring movement to preparing for running and eventually returning to sport, rehabilitation should be guided by your individual progress and goals.
If you’re approaching the running stage of your recovery, a rehabilitation assessment can help identify whether your knee is ready for the next step and what you might need to work on first.
Because getting back to running isn’t just about how long it’s been since surgery. It’s about making sure you’re ready for what comes next.
If you’d like guidance with your ACL rehabilitation, contact SportsPlus Physiotherapy in Highgate Hill to arrange an appointment.
