What Should ACL Return-to-Sport Testing Actually Include?

Return-to-sport testing after ACL reconstruction should not be a single exam that you pass at the end of rehabilitation. It is better viewed as an ongoing process: measure, expose, adapt, reassess and progressively build toward the demands of your sport.

There are many excellent ACL tests. Strength testing matters. Jump and hop testing matters. Reactive performance, movement quality, psychological readiness and sport-specific testing can all add useful information. But no single test — and no single battery completed on one day — can recreate the accumulated demands of training and competition.

Return to sport is a process, not a test day

One of the most important changes in return-to-sport thinking is the recognition that return is a continuum. An athlete progresses from rehabilitation into participation, then back to sport, and ultimately back toward performance. Testing should help guide that journey rather than act as a one-off gate at the end.

An athlete can perform very well during a controlled testing session and still be underprepared for repeated accelerations, decelerations, changes of direction, fatigue, contact, unpredictable movement and the cumulative load of several training sessions in a week.

What should ACL return-to-sport testing include?

The exact battery should depend on the athlete, their stage of rehabilitation, injury history, available equipment and — most importantly — what they are returning to. A field-sport athlete returning to cutting and reactive play should not necessarily be assessed in the same way as a distance runner.

I generally want information across several domains:

• Knee status: symptoms, swelling, range of motion and tolerance to current training.
• Strength and capacity: particularly quadriceps and hamstring function, but also the wider lower limb where relevant. Side-to-side symmetry is useful, but absolute and bodyweight-relative capacity matter too.
• Explosive performance: the ability to produce force during jumping and other fast actions.
• Reactive qualities: how effectively the athlete can absorb and reproduce force when time on the ground becomes short.
• Landing and force absorption: not simply whether a landing is completed, but how the athlete accepts load.
• Movement quality: acceleration, deceleration, cutting, lateral movement, rotation and the strategies used to complete them.
• Sport-specific capacity: progressively exposing the athlete to the speed, volume, direction changes and uncertainty required by their sport.
• Confidence and readiness: whether the athlete trusts the knee and feels able to express their physical capacity when demands increase.

I have core tests — but I don’t believe in one fixed battery for everyone

There are tests I use consistently because they give valuable benchmarks and allow progress to be tracked over time. But I also use a much broader library of tests throughout rehabilitation.

Which tests I choose — and when I use them — depends on what I am seeing. An athlete with a history of hamstring problems may need a different emphasis from an athlete who struggles to absorb force through the reconstructed knee. A soccer player may need different movement exposures from a runner. An athlete who looks excellent in predictable jumping tasks may need more information from reactive or multidirectional work.

The purpose of testing is not to complete a checklist. It is to ask better questions about the individual athlete.

A passed test can still hide a compensation

Performance outcomes can look reassuring while the strategy used to achieve them tells a different story.

A well-known example is the single-leg hop for distance. Research has shown athletes after ACL reconstruction achieving approximately 97% symmetry in hop distance while symmetry in the work performed by the knee during propulsion was far lower. Athletes could maintain the distance by shifting work toward the hip and ankle and changing trunk and pelvis strategy.

That is clinically important. If we record only the distance, the athlete may appear to have passed. If we watch how the task is completed — or measure the forces and joint strategy — we may reach a different conclusion.

This is why technology is useful but does not replace experienced observation. Force plates, dynamometry and performance measures can quantify things the eye cannot. The coach’s eye can identify strategies that a headline score can miss. The strongest assessment combines both.

Testing should influence training — and training should influence testing

A useful test identifies a priority. Rehabilitation then gives the athlete enough exposure to change that quality. We reassess, progress the demand and see whether the change holds when the task becomes faster, more complex or more fatigued.

That makes return-to-sport testing fluid rather than static. You might assess maximal strength earlier, introduce jump profiling as the athlete develops power, add reactive tasks as ground-contact demands increase, and progress toward cutting, deceleration and unplanned movement as sport becomes closer.

Not every athlete needs every test. The question is whether the testing helps us make a better decision and build a better next phase.

The missing test: weeks of appropriate exposure

This may be the most important part of return to sport that cannot be captured in a single testing session.

Before returning fully, an athlete should have accumulated an appropriate progression of the things their sport actually requires. That may include running volume, sprint exposure, repeated accelerations and decelerations, cutting, jumping, reactive movement, non-contact practice, controlled contact and progressively less restricted training.

These exposures allow us to see how the knee and the athlete respond not just to one successful repetition, but to repeated load over days and weeks. Symptoms, confidence, movement quality and performance can all change as volume and intensity rise.

A test battery is therefore best viewed as a series of snapshots within a much longer film.

So when is an athlete ready?

There is no perfect test that can guarantee a safe or successful return. Return-to-sport decisions involve risk, and the relevant criteria depend on the athlete and the sport.

For me, the goal is to build confidence from multiple pieces of information: sufficient strength and physical capacity; explosive and reactive qualities; effective movement strategies; tolerance to progressive sport exposure; appropriate conditioning; confidence in the knee; and enough sport-specific training to demonstrate that these qualities survive outside the testing environment.

Key research

• Ardern CL, et al. 2016 Consensus statement on return to sport from the First World Congress in Sports Physical Therapy, Bern. Br J Sports Med. 2016.
• van Melick N, et al. Evidence-based clinical practice update: practice guidelines for anterior cruciate ligament rehabilitation based on a systematic review and multidisciplinary consensus. Br J Sports Med. 2016.
• Kotsifaki A, et al. Single leg hop for distance symmetry masks lower limb biomechanics: time to discuss hop distance as decision criterion for return to sport after ACL reconstruction? Br J Sports Med. 2022.
• Kotsifaki A, et al. Symmetry in Triple Hop Distance Hides Asymmetries in Knee Function After ACL Reconstruction in Athletes at Return to Sports. Am J Sports Med. 2022.