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Why successful ACL recovery takes more than a great physical therapist, a perfect program or a passing test.

Recently, I came across a young physical therapist on social media claiming to have rehabilitated thousands of ACL injuries without a single reinjury.

It frustrated me.

After more than twenty years working in physical therapy, I’ve come to appreciate just how difficult it is to make claims like that. To substantiate such a claim, you would need to follow thousands of athletes for years after discharge and reliably track any subsequent injuries.

With high ACL reinjury rates attracting attention, some clinicians are selling a magic pill approach to rehabilitation. And I don’t believe it reflects reality.

I don’t sell a magic solution. I believe in hard work, skilled guidance and a genuine understanding of just how difficult this journey can be.

Having worked in professional sport environments, I’ve seen that rehabilitation is often harder than playing.

Athletes deserve an honest conversation about what influences their recovery, what we can control and what even the best rehabilitation cannot guarantee.

No Two ACL Injuries Are the Same

We often discuss ACL reconstruction as though every athlete begins rehabilitation from the same starting point.

They don’t.

One athlete may have an isolated ACL injury. Another may have significant meniscal damage, cartilage involvement, additional ligament injuries or a complicated surgical history.

These differences influence pain, swelling, loading restrictions, strength development and potentially the longer-term health of the knee.

There are also biological differences between individuals, including variations in healing, anatomy and factors we don’t fully understand.

Even with similar operations, two knees may respond very differently.

And while returning to sport is understandably the immediate goal, we should also consider what happens to that knee five, ten or twenty years later.

The Athlete You Start With Matters

Athletes arrive with very different physical histories.

Some have years of structured strength training behind them. Others have spent years participating in sport but have almost no experience in the gym.

They may be competitive, technically skilled athletes yet lack the strength, reactive capacity or movement skills required for high-speed athletic actions.

Some have movement strategies developed over many years that may be difficult to change.

These aren’t necessarily consequences of the ACL injury. They may have existed long before it.

How much physical development can we realistically expect to achieve in six, nine or even twelve months?

We can make enormous progress. But an athlete with very little training history may still have years of physical development ahead.

Strength, speed, coordination and movement skills develop through sustained training and exposure. They aren’t permanently solved by completing a rehabilitation program.

This is why I believe ACL rehabilitation should aim to restore the athlete, not just the knee.

Rehabilitation Doesn’t Happen in a Perfect Environment

There is another reality that rarely features in polished rehabilitation content.

Life.

Athletes have jobs, families, financial responsibilities and competing priorities.

Some have consistent access to physical therapy. Others face insurance restrictions, significant costs or interruptions in treatment.

I’ve seen how these circumstances can influence rehabilitation, regardless of an athlete’s motivation or commitment.

It’s easy to present a beautiful pathway showing a smooth progression from surgery to strength, jumping, running and sport.

In reality, progress stalls, symptoms fluctuate and plans need to adapt.

A good rehabilitation framework must accommodate these realities rather than pretend they don’t exist.

I’ve Never Had a Perfect ACL Rehabilitation

This might sound like an unusual admission from someone offering specialist ACL rehabilitation.

But I have never delivered a perfect ACL rehabilitation.

There have been athletes whose outcomes I believe could have been better. Decisions I would make differently with hindsight. Physical qualities I wish we’d developed further. And occasions when I know I could have done something better.

Some of those limitations were outside my control. Others weren’t.

But there’s another reason I say I’ve never delivered a perfect rehabilitation.

It’s a mindset.

I don’t believe I should ever reach a point where I consider my approach complete.

I want to continually scrutinize my clinical decisions, question my assumptions and reassess how I assess, coach and develop an athlete.

The goal isn’t to convince myself I’ve developed the perfect system. It’s to keep making the process better.

The Physical Therapist Matters. A Lot.

None of this diminishes the importance of choosing the right physical therapist.

Quite the opposite.

ACL rehabilitation requires more than following a protocol or selecting exercises.

A clinician needs to understand the injury, the athlete’s presentation and the demands of their sport.

They need to know what to measure, how to interpret the findings and how those findings should influence training.

That means looking beyond simple limb symmetry to consider strength relative to body weight, force production, reactive qualities, movement strategy and physical capacity. For more detail, see what ACL return-to-sport testing should include.

It also requires knowing when to progress, when to modify loading and when a knee isn’t responding as expected.

Objective testing is essential, but testing alone doesn’t develop an athlete.

The skill lies in interpreting the information and translating it into meaningful physical development.

Not every physical therapist has the same experience, expertise or opportunity to deliver comprehensive late-stage athletic rehabilitation.

Preparing someone to return to demanding sport requires specialist knowledge and coaching skills.

Choosing the right clinician matters. But even the best clinician cannot guarantee the outcome.

Your Physical Therapist Cannot Do Your Rehabilitation for You

An athlete might spend one or two hours each week working directly with their physical therapist.

The rest of the week matters enormously.

The clinician can assess, educate, plan, coach and adapt.

But the athlete has to do the work.

Developing meaningful strength requires consistent training. Improving movement skills requires repetition and exposure. Building tolerance for jumping, braking, acceleration and multidirectional movement requires progressively challenging the body.

I’ve worked with athletes who have been incredibly diligent throughout their rehabilitation. I’ve also worked with athletes who have struggled with consistency.

Sometimes that’s understandable. Life makes adherence difficult.

But we still need to be transparent about the consequences.

If important training exposures are repeatedly missed, or strength and athletic development aren’t consistently progressed, the athlete may be left with physical qualities that fall short of the demands of their sport.

The athlete needs to understand the commitment involved and take ownership of their rehabilitation.

That doesn’t mean doing everything perfectly. It means recognizing that what happens outside the treatment room matters just as much as what happens inside it.

You Don’t Really Graduate From an ACL Injury

There is an understandable desire to reach a point where the athlete is cleared, discharged and able to put rehabilitation behind them.

But physical qualities require maintenance.

Strength can decline. Training exposure changes. Athletic demands increase.

This is true for all athletes, not just those who have experienced an ACL injury.

Someone returning from ACL reconstruction may have spent considerable time rebuilding qualities that were lost or underdeveloped. We cannot assume those qualities will maintain themselves indefinitely.

You may finish formal ACL rehabilitation, but you don’t graduate from the responsibility of maintaining your physical capacity.

That doesn’t mean living in fear of another injury or remaining a rehabilitation patient forever.

It means making strength training, movement development and exposure to the demands of sport part of your ongoing athletic preparation.

There Is No Magic ACL Rehabilitation Program

I understand why athletes are attracted to confident promises.

An ACL injury is frightening. Rehabilitation is long, expensive and often uncertain.

Of course someone wants to hear that there is a system capable of guaranteeing a successful return.

But we should be careful about confusing confidence with certainty.

There is no single exercise, testing battery, rehabilitation framework or physical therapist capable of removing every risk.

That doesn’t mean all approaches are equal.

The quality of rehabilitation matters enormously. Objective testing, physical development, movement coaching and clinical judgment all have important roles.

And so does the commitment of the athlete.

We should be ambitious about what ACL rehabilitation can achieve while remaining transparent about its limitations.

The best ACL rehabilitation isn’t something a physical therapist does to an athlete. It’s something they build together.

For athletes looking for individualized support, learn more about ACL rehabilitation in Portland at KICK Performance Therapy.

Research and Further Reading

Wiggins AJ et al. (2016). Risk of Secondary Injury in Younger Athletes After Anterior Cruciate Ligament Reconstruction: A Systematic Review and Meta-analysis.

Meniscus Status at Anterior Cruciate Ligament Reconstruction Associated With Radiographic Signs of Osteoarthritis at 5- to 10-Year Follow-up: A Systematic Review.

Aspetar Clinical Practice Guideline on Rehabilitation After Anterior Cruciate Ligament Reconstruction.

ACL rehab rarely goes wrong because of one major mistake. More often, small things are missed at different stages of the process, and those misses become more important as the demands increase.

A knee that never truly settles. Quadriceps function that never fully returns. Physical development that doesn’t progress far enough. Movement compensations that aren’t identified. Testing that becomes a box-ticking exercise rather than something that guides rehabilitation.

By the time an athlete is trying to run, jump, cut and return to sport, those earlier gaps can become much harder to ignore.

Sometimes ACL rehab goes wrong at the beginning

Some of the problems we see later in ACL rehabilitation started much earlier.

An athlete may progress through the stages of rehab without ever fully restoring the basics: a quiet knee, full motion and good quadriceps function.

Months later, they may be running, jumping and lifting, but still dealing with recurrent swelling, an extension deficit or a quadriceps that has never properly recovered.

Moving forward in rehab doesn’t necessarily mean the early problems have been resolved.

Sometimes progressing an athlete means first identifying what was missed.

Strength is essential. But it isn’t the end point.

Restoring quadriceps and lower-limb strength is fundamental after ACL reconstruction.

But eventually the athlete needs more than strength alone.

Sport requires the ability to produce force quickly, absorb force, express power, repeat high-intensity efforts and tolerate increasingly demanding athletic tasks.

Rehabilitation therefore needs to evolve from restoring strength toward developing the broader physical qualities required for sport.

The question changes from “Is this athlete getting stronger?” to:

“Are we preparing this athlete for what their sport actually requires?”

Movement needs to be coached

Athletes don’t return to a collection of gym exercises.

They return to accelerating, decelerating, landing, cutting, reacting and making decisions at speed.

Movement coaching is a skill in itself.

Analyzing how an athlete lands, brakes or changes direction, and knowing how to progressively coach those qualities, requires experience and deliberate practice.

We shouldn’t assume movement quality automatically returns because an athlete gets stronger or starts running again.

If we want athletes to return to movement, we have to train movement.

A test score doesn’t tell us everything

Objective testing is an important part of ACL rehabilitation. Strength, jump and performance measures can reveal deficits that aren’t obvious from observation alone.

But numbers need interpretation.

A test result tells us what an athlete achieved. How they achieved it matters too.

The strategies and compensations used to complete a task can reveal things that a score alone may miss.

This is also why a single number such as 90% limb symmetry shouldn’t be viewed as the destination. Symmetry can be useful, but it doesn’t necessarily tell us whether both limbs are strong enough, how the athlete produced the result or whether they’re prepared for their sport.

Testing should ultimately answer a more useful question:

What does this tell us about what the athlete needs next?

Passing return-to-sport testing isn’t the finish line

Return-to-sport testing has helped move ACL rehabilitation beyond simply waiting a certain number of months after surgery.

But passing a battery shouldn’t become the end goal either.

An athlete can perform well in controlled testing and still have had very little exposure to speed, repeated efforts, reactive movement, fatigue or the unpredictability of sport.

They may also test well physically but still not feel ready to return.

Testing should guide the rehabilitation process, not replace it.

Small misses become bigger as the demands increase

Early in rehabilitation, a deficit can be relatively easy to compensate for.

Later, the demands expose it.

Walking becomes running.
Strength becomes power.
Controlled jumping becomes reactive jumping.
Planned movement becomes unpredictable movement.
Rehabilitation becomes sport.

This is why ACL rehabilitation needs to keep evolving.

What matters at three months isn’t necessarily what matters at nine months.

Good ACL rehab progresses with the athlete

There isn’t one perfect ACL exercise, one perfect testing battery or one milestone that tells us rehabilitation has been successful.

Early on, the priority may be restoring a quiet, mobile knee and recovering quadriceps function.

Then comes developing strength and the physical qualities required for sport.

Movement becomes faster and more complex. Testing helps identify what is improving and what still needs attention. Exposure progressively begins to resemble the demands the athlete is returning to.

At every stage, the question should be:

What does this athlete need next?

ACL rehabilitation should restore the athlete, not just the knee.

The goal isn’t simply to rehabilitate a reconstructed ACL.

It’s to rebuild the athlete around it.

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Not sure where your ACL rehab is getting stuck?

Whether you’re early in rehabilitation or approaching return to sport, an objective assessment can help identify what’s progressing well, what may have been missed and what should come next.

KICK Performance Therapy provides ACL rehabilitation and return-to-sport assessment in Portland, Oregon, with online ACL assessment available for athletes further afield.

Your strength numbers look good. Your side-to-side symmetry may even be above 90%. So why does the reconstructed leg still feel weak?

This is a common experience after ACL reconstruction. The answer is often not that the strength test is wrong. It is that “strength” is a much bigger quality than the number produced during one controlled test.

A maximal isometric or slow strength test tells us something important: how much force you can produce under those particular conditions. Sport asks whether you can access, absorb and repeat force quickly — while moving, reacting and becoming fatigued.

A strong test does not always mean a fully restored quadriceps

One of the first things I look at is whether the strength result fits the rest of the athlete.

An athlete can produce a surprisingly good peak isometric force while the reconstructed-side quadriceps still looks visibly smaller. A single maximal value does not directly tell us that muscle size, architecture, endurance and the ability to express force across different speeds and joint positions have all returned.

That distinction matters. Quadriceps atrophy is common after ACL reconstruction, and muscle size is related to strength — but the relationship is not perfect. Neural factors, testing position, familiarization and an athlete’s ability to recruit the available muscle can all influence a maximal test.

The “skinny but strong” quadriceps

Sometimes an athlete reaches a respectable strength number while the quadriceps still appears noticeably underdeveloped compared with the other side. I would not ignore that simply because the dynamometer says the athlete is strong.

Think of the maximal test as one expression of the system. The athlete may be very good at recruiting what they have for a brief effort, but reduced muscle mass may become more relevant when we ask the limb to produce high forces repeatedly, work through different joint angles, absorb eccentric load or maintain performance as fatigue develops.

This is one reason I combine strength testing with the clinical picture: muscle development, training history, movement, jumping and the athlete’s response to progressively harder tasks.

How quickly can you use your strength?

Maximal force and rapid force production are not the same thing.

Rate of force development describes how rapidly force rises. That matters in sport because many actions happen in a fraction of the time available during a maximal strength test. Research after ACL reconstruction has demonstrated that athletes can recover maximal voluntary strength while deficits in rapid force production remain.

This can help explain why an athlete feels strong in the gym but less convincing when sprinting, jumping, changing direction or reacting quickly.

Can you absorb force as well as produce it?

Sport is not only about pushing. It is also about braking.

Landing, decelerating and changing direction require the lower limb to accept and control substantial forces. An athlete may demonstrate good concentric or isometric strength yet still avoid loading the reconstructed knee during these tasks.

That is why I am interested in eccentric capacity and movement strategy. Does the athlete actually use the knee when absorbing force, or do they find a way to shift demand toward the hip, ankle, trunk or opposite limb?

Relative strength matters too

Side-to-side symmetry tells us how similar the limbs are. It does not necessarily tell us whether either limb is strong enough for the athlete’s body mass and sporting demands.

An athlete can be symmetrically weak. Conversely, a reconstructed limb can remain somewhat asymmetrical while both limbs have developed substantial absolute capacity. This is why I prefer to interpret symmetry alongside absolute and, where appropriate, bodyweight-relative strength rather than using one percentage in isolation.

What happens after the first repetition?

Many strength tests capture a short maximal effort. Sport repeatedly asks for force.

If the reconstructed limb loses output more rapidly, movement quality changes under fatigue or the athlete progressively unloads the knee, a single peak value may never reveal the problem. Capacity across repeated jumps, repeated contacts, running and progressively demanding training can therefore provide information that a one-off maximal test cannot.

Sometimes the weakness you feel is a movement problem

Athletes do not experience their knee as a dynamometer number. They experience it while moving.

If you hesitate when loading the reconstructed side, shorten ground contact differently, reduce knee contribution during a jump or rely more heavily on another joint, the limb may feel weak even when maximal strength is respectable.

That sensation can be useful information. Rather than dismissing it because the strength test “passed,” I want to understand where the mismatch appears and what changes when the task becomes faster, more reactive or more sport-like.

So what should we test when strength looks good but the leg doesn’t feel right?

• Maximal strength: confirm that the apparent strength recovery is real and consider absolute and relative values, not symmetry alone.
• Muscle development: consider whether visible or measured quadriceps atrophy remains relevant to the athlete’s overall capacity.
• Rapid force production: assess whether force can be generated quickly rather than only maximally.
• Explosive and reactive performance: examine jumping and shorter ground-contact tasks where appropriate.
• Eccentric and braking capacity: look at how the athlete absorbs force during landing and deceleration.
• Movement strategy: assess whether performance is being achieved through compensations.
• Repeatability and fatigue: determine whether quality and output persist as demands accumulate.
• Sport exposure: establish whether the athlete has actually had enough progressive high-speed and sport-specific work to translate gym capacity into performance.

I have core tests that I use regularly, but I also draw from a wider testing toolbox depending on the athlete, their injury history, sport and what I am seeing during rehabilitation. The goal is not to collect more numbers for the sake of it. It is to identify the quality that is still limiting the athlete.

Strength can explain a lot — but it cannot explain everything

I strongly believe in strength testing. When strength is genuinely deficient, improving it often has a remarkable effect on movement, confidence and performance.

But when an athlete tells me, “My strength tests are good, but the leg still doesn’t feel right,” I don’t think the conversation should end there.

That is often the point at which we need to ask a better question: what can this athlete do with the strength they have?

Key research

• Angelozzi M, et al. Rate of force development as an adjunctive outcome measure for return-to-sport decisions after anterior cruciate ligament reconstruction. J Orthop Sports Phys Ther. 2012.
• Thomas AC, Wojtys EM, Brandon C, Palmieri-Smith RM. Muscle atrophy contributes to quadriceps weakness after anterior cruciate ligament reconstruction. J Sci Med Sport. 2016.
• Kotsifaki A, et al. Research demonstrating that symmetrical hop distance can mask persistent asymmetries in knee function after ACL reconstruction.
• Wellsandt E, Failla MJ, Snyder-Mackler L. Limb Symmetry Indexes Can Overestimate Knee Function After Anterior Cruciate Ligament Injury. J Orthop Sports Phys Ther. 2017.

“When can I start running?” is one of the most common questions after ACL reconstruction. My answer is usually another question: what kind of running are we trying to return you to?

For someone whose goal is recreational distance running, rebuilding steady running volume may be exactly the right progression. For an athlete returning to soccer, basketball, ultimate or another high-speed multidirectional sport, however, a long period of slow jogging should not automatically become the centerpiece of mid-stage rehabilitation.

Running is an important milestone. But the goal is not simply to prove that you can jog. The goal is to progressively prepare you for the forces, speeds, decisions and repeated high-intensity actions your sport actually requires.

Return to running should be criteria-based, not calendar-based

Time since surgery matters because healing biology matters. But reaching a particular postoperative week does not automatically mean the knee is ready to run.

Current clinical guidance recommends combining time with clinical and functional criteria. Suggested markers include full knee extension, close to full flexion, little or no swelling, sufficient quadriceps strength and the ability to tolerate repeated single-leg hopping without pain.

I use core markers like these, but I do not believe one fixed battery suits every athlete. I also draw from a wider range of tests depending on the athlete’s history, sport, graft, current deficits and what I am seeing throughout rehabilitation.

Before running, I want to see the basics

Running should not become a way of bypassing unfinished rehabilitation.

Before progressing, I want confidence that the knee is clinically settled and that the athlete has developed enough strength, control and elastic capacity for the next demand. That can include knee range and swelling, quadriceps and lower-limb strength, calf capacity, controlled single-leg loading, jumping and landing preparation, repeated low-level reactive contacts and movement quality.

The exact markers change with the individual. The important principle is that the athlete earns progression by demonstrating capacity rather than simply reaching a date on the calendar.

Jogging and returning to athletic movement are not the same progression

I have no objection to steady jogging when it serves the athlete’s goals. If running itself is your sport or something you enjoy, rebuilding it progressively makes sense.

For a multidirectional athlete, though, I often prefer to place greater emphasis on drill-based running and movement progressions. These allow us to deconstruct athletic actions and progressively expose the athlete to positions, rhythms and forces that will later underpin faster sport.

Rather than accumulating large amounts of slow running simply because it is easy to prescribe, we can use appropriate drills to develop running mechanics, stiffness and elastic qualities, acceleration positions, force application and eventually greater speed.

This does not mean going from rehabilitation straight into maximal sprinting. It means building a deliberate bridge from controlled movement to higher-intensity movement.

Why I don’t want jogging to dominate the middle of rehab

A long, generic return-to-run progression can add a substantial amount of training volume. For some athletes that volume is useful. For others it competes with the qualities they most need to restore: strength, power, reactive ability, speed and high-quality athletic movement.

If every week becomes longer bouts of low-intensity running on top of gym work and rehabilitation, the athlete can simply become tired without becoming meaningfully better prepared for the actions associated with their sport.

Most non-contact ACL injuries are not sustained during comfortable straight-line jogging. They are more commonly associated with demanding actions such as rapid deceleration, change of direction or landing. That does not make jogging bad. It means jogging alone provides limited preparation for the situations we ultimately care about.

Can drill-based movement begin before continuous running?

In many athletes, elements of athletic movement can be introduced before they are completing meaningful volumes of continuous running — provided the task is appropriate for their stage of healing and current capacity.

Early work may be relatively simple: athletic postures, marching and rhythm drills, controlled foot contacts, low-level landing tasks and rehearsed movement patterns. As the athlete demonstrates success, those tasks can progress in speed, amplitude, force and complexity.

This creates a continuum rather than a sudden transition from “rehab exercises” to “sports training.”

The coach’s eye still matters

Objective testing gives us information that observation alone cannot. But numbers do not tell the whole story.

I also want to see how the athlete moves. Are they accepting load through the reconstructed limb? Do they look comfortable during repeated contacts? Are they creating unnecessary compensations? Does movement deteriorate when speed increases? Can they reproduce a task consistently rather than simply complete one good repetition?

The combination of objective testing, clinical response and experienced movement observation is more useful to me than a single “return-to-run test.”

Physical readiness is only part of readiness

The first running and jumping progressions can also feel psychologically significant after ACL reconstruction. Some athletes are eager to move faster; others remain hesitant despite good physical testing.

That response matters. Progression should create successful exposures that build trust in the limb rather than forcing an athlete through a stage simply because the protocol says it is time.

So when can you start running?

There is no single number that answers that question for everyone. A useful decision considers healing time, symptoms, swelling and range of motion alongside objective strength, jumping and reactive capacity, movement quality and psychological readiness.

And for athletes returning to high-speed sport, I would broaden the question:

When are you ready to start rebuilding athletic movement — and what progression will best prepare you for the sport you actually want to return to?

That is a much more useful rehabilitation question than simply asking when you are allowed to jog.

Key research

• Aspetar. Clinical practice guideline on rehabilitation after anterior cruciate ligament reconstruction. Br J Sports Med. 2023.
• Rambaud AJM, Ardern CL, Thoreux P, Regnaux JP, Edouard P. Criteria for return to running after anterior cruciate ligament reconstruction: a scoping review. Br J Sports Med. 2018.
• Burgi CR, et al. Which criteria are used to clear patients to return to sport after primary ACL reconstruction? A scoping review. Br J Sports Med. 2019.

Being cleared after ACL reconstruction and feeling ready to return to sport are not always the same thing.

You may have restored your range of motion. Your strength numbers may look good. You may have passed hop tests and reached the expected stage of rehabilitation. Yet when you imagine sprinting, cutting, reacting to another player or returning to competition, something still doesn’t feel right.

That feeling deserves attention. Return to sport is physical, psychological and highly individual — and many of the qualities that make an athlete feel capable again should be developed long before the final return-to-sport test.

Cleared does not always mean ready

Return-to-sport clearance is an important milestone, but it cannot perfectly reproduce the demands of sport. Research consistently shows that athletes can still demonstrate physical deficits around the time they are cleared, while psychological readiness is also strongly associated with whether athletes actually return.

This helps explain why an athlete can look good on paper but still feel a significant gap between rehabilitation and competition.

Strength matters — but sport asks you to express it

I strongly believe in strength testing after ACL reconstruction. If the quadriceps, hamstrings or wider lower limb remain significantly under-strength, that can explain many of the compensations and limitations an athlete experiences.

But maximal strength is one physical quality. An athlete may be strong in a controlled test and still lack explosive strength, rate of force development, eccentric braking capacity or reactive strength. They may be able to produce force, but not yet access and organize it at the speed their sport demands.

That is why strength should be considered a foundation rather than the final destination.

These qualities can be developed much earlier

Athletic rehabilitation should not suddenly begin when an athlete is almost ready to return.

From earlier stages of ACL rehabilitation, we can begin rebuilding the qualities that later make sport feel familiar: athletic positions, controlled movement strategies, confidence accepting load through the reconstructed limb and progressively faster force production.

As strength and healing progress, those foundations can evolve into jumping, landing, acceleration, deceleration, multidirectional movement and eventually reactive, sport-relevant tasks. The intensity changes throughout rehabilitation, but the goal of preparing an athlete to move like an athlete can be present from much earlier.

Sport demands more than physical capacity

Sport requires more than strength, power and movement capacity. Athletes also have to process information, make decisions and coordinate an appropriate movement response — often at speed and without time to consciously think about the knee.

These demands are difficult to reproduce with predictable rehabilitation exercises alone. An athlete may perform extremely well when they know exactly what movement is coming next, yet feel very different when they have to respond to another player, a ball, changing space or an unexpected cue.

That is one reason rehabilitation can progress beyond predictable drills. As appropriate, tasks can incorporate external cues, decision-making, reaction, visual information, opponents or teammates, dual-task demands and increasingly unpredictable movement. The aim is not simply to make exercises complicated. It is to reconnect physical capacity with the perception-action demands of sport.

The mental side of returning can feel overwhelming

An athlete can pass every physical test placed in front of them and still not feel psychologically ready.

Fear of reinjury, hesitation, reduced confidence and uncertainty about whether the knee will cope are common after ACL reconstruction. Research shows that psychological readiness is meaningfully associated with return to sport, even when conventional measures of knee function are similar.

This should not be dismissed as something the athlete simply needs to “get over.” It should be explored. What exactly feels threatening? Is it contact? Cutting off the reconstructed side? Landing in traffic? An unpredictable opponent? Fatigue? Returning to the environment in which the injury occurred?

Those answers can help shape rehabilitation. Appropriate graded exposure can allow an athlete to experience successful movement at progressively greater speed, complexity and uncertainty. In some cases, psychological support beyond physical therapy may also be valuable.

Confidence is difficult to test into existence

Confidence often grows through evidence.

Evidence that the leg is strong. Evidence that you can land and absorb force. Evidence that you can sprint. Evidence that you can cut. Evidence that you can react without protecting the knee. And, importantly, evidence accumulated across weeks of progressively harder training rather than one successful testing session.

This is where return-to-sport testing and return-to-sport preparation need to work together. Testing can identify what is missing. Training gives the athlete the exposure to change it. Reassessment tells us whether that change persists as the task becomes faster and less predictable.

If you’ve been cleared but don’t feel ready, what should you look at?

• Absolute strength and symmetry: are you genuinely strong enough, or simply similar from side to side?
• Explosive and reactive qualities: can you produce, absorb and reproduce force quickly?
• Movement strategy: are you confidently using the reconstructed limb or finding subtle ways around it?
• Conditioning: can you maintain movement quality and decision-making as fatigue increases?
• Athletic exposure: have you built enough sprinting, deceleration, cutting, jumping and sport-specific training over time?
• Neurocognitive demands: have you progressed beyond rehearsed tasks into reacting, deciding and moving in response to external information?
• Psychological readiness: what situations still create hesitation or fear, and have they been progressively addressed?

The answer will not be identical for every athlete. That is why I prefer to use testing as part of an ongoing process rather than a universal pass/fail checklist.

Key research

• Webster KE, Hewett TE. What is the Evidence for and Validity of Return-to-Sport Testing after Anterior Cruciate Ligament Reconstruction Surgery? A Systematic Review and Meta-Analysis. Sports Med. 2019.
• Webster KE, Feller JA. Research examining psychological readiness and the ACL Return to Sport after Injury (ACL-RSI) scale.
• Piussi R, et al. Research examining knee confidence, fear of movement and psychological readiness following ACL reconstruction.
• Grooms DR, et al. Research examining neuroplasticity and sensorimotor control following ACL injury and reconstruction.