How to Know if You’re Ready to Return to Soccer After an ACL Injury

By: Elizabeth Ng, MScPT, Registered Physiotherapist

Coming back to soccer after an ACL injury is exciting — but it can also be dangerous if your body isn’t ready. A lot of athletes make the mistake of thinking that once enough time has passed, they’re good to go. But research shows that time alone doesn’t tell the whole story. Your body needs to pass specific physical and mental tests before you step back onto the field.

Soccer is tough on your knees. Sprinting, jumping, cutting, and changing direction quickly all put a lot of stress on the joint. That’s why doctors, physiotherapists, and athletic therapists now look at clear, measurable signs and not just a calendar, to decide when an athlete is truly ready.

Here are 5 key things to check before returning to full soccer activity.

1. Your Knee Should Have No Pain or Swelling

The first and most basic sign your knee is ready is that it doesn’t hurt and isn’t swollen during everyday activities or exercise.

Signs your knee may not yet be ready include:

• Pain during running, cutting, or jumping
• Swelling after regular daily activities
• Swelling after workouts
• Stiffness the next day
• A feeling of instability or giving way

A small amount of muscle soreness is normal during rehab, but joint swelling or sharp pain suggests the knee may still be overloaded.

One useful self-check is the “24-hour response.” After a harder workout or practice, ask yourself:

• Does the knee swell later that day?
• Is it more painful the next morning?
• Does it feel stiff or unstable?

If you answer “yes” to any of these, your knee is not ready for the full demands of soccer yet.

2. You Should Have Full Symmetrical Range of Motion

Your injured knee should be able to move just as well as the non-injured knee. 

This means you have:

• Full knee extension (full straightening of the knee)
• Full knee flexion (full bending of the knee)

Loss of motion can affect:

• Running mechanics
• Deceleration
• Jump landing
• Change-of-direction control

Even small differences in extension can change how forces travel through the knee during sport.

You can self-test by comparing both sides:

• Can you fully straighten both knees equally when laying flat?
• Can you sit back into a deep squat comfortably?
• Can you kneel or sit back on your heels equally on both sides?

If one knee feels blocked, stiff, or restricted, more rehabilitation may still be needed.

3. Strength Symmetry Matters More Than “Feeling Strong”

Feeling strong isn’t the same as being strong. After an ACL injury, many athletes regain confidence quicker than fully regaining their strength. One of the most common lingering weaknesses is in the quadriceps muscle. Early in the injury, a strong quadricep muscle will further stress the already weakened ACL, and as a protective reaction, the body turns down the activity of the quadricep muscle. As your ACL heals, the quadricep requires special attention to regain its strength.

Current return-to-play recommendations often use a Limb Symmetry Index (LSI) to compare the strength of your injured leg to your healthy leg. The goal is to have your injured leg perform 90% as well as your healthy leg. So if your healthy leg can lift 100lbs of weight, then your injured leg should be able to lift at least 90lbs before returning to soccer. Both the quadricep and hamstring muscles must reach this level. The LSI is expressed as a percentage, and the formula is:

LSI= Uninjured Limb Value

Injured Limb Value           ×100% 

An LSI of 90% means the injured leg performs at least 90% as well as the uninjured side; an LSI of 100% means the injured and uninjured leg performs equally well.

Simple Strength Self-Checks

Most people do not have access to testing equipment, but you can spot signs of weakness and unequal strength by checking for these:

• Difficulty with single-leg squats on the injured side
• Fatigue much earlier on one leg
• Shaking or loss of control
• Uneven jumping or landing
• Favoring the uninjured side during lifts

Exercises often used to compare sides include:

• Single-leg squat
• Bulgarian split squat
• Step-down test
• Single-leg bridge
• Single-leg calf raises

Strength should not only be present during slow movements, but also during explosive and reactive tasks.

4. Hop Testing Helps Measure Real-World Function

One common way to measure readiness is the Hop test because it challenges:

• Strength
• Power
• Stability
• Landing control
• Confidence

A typical hop test battery includes:

1. Single hop for distance
2. Triple hop for distance
3. Crossover hop for distance
4. Timed hop over 6 meters

Again, athletes generally aim for at least 90% limb symmetry.

Single Hop Example

If your uninjured leg hops 150 cm and your injured leg hops 138 cm:

LSI=138/150×100=92%

That would meet the recommended ≥90% criterion.

However, distance alone is not enough. Quality of movement matters too.

Watch for:

• Knee collapsing inward
• Poor balance on landing
• Hesitation before jumping
• Heavy or stiff landings
• Fear of loading the injured leg

Sometimes athletes can “pass” distance tests while still showing poor movement control.

Recording yourself on video can help identify asymmetries.

5. Psychological Readiness Is Extremely Important

Physical recovery is only part of returning to sport.

Many athletes experience:

• Fear of reinjury
• Hesitation during cutting or pivoting
• Lack of trust in the knee
• Anxiety during contact situations

This is called kinesiophobia — fear of movement due to concern about injury.

An athlete may appear physically strong but still avoid full-speed movement subconsciously. This can actually increase injury risk because movement becomes stiff or hesitant.

Questions to ask yourself:

• Do I trust my knee during fast movements?
• Am I avoiding certain cuts or turns?
• Do I feel nervous during contact drills?
• Am I constantly thinking about the knee while playing?

Confidence usually improves gradually through progressive exposure:

• Controlled drills
• Non-contact practice
• Small-sided games
• Full training
• Competitive matches

Rushing this process can make return to soccer more difficult mentally.

Returning to Soccer Is a Process, Not a Single Date

Being cleared for soccer should not depend only on how many months have passed since injury or surgery.

Instead, you should demonstrate:

• No pain or swelling
• Full symmetrical motion
• Strong quadriceps and hamstrings
• Symmetrical hop performance
• Good movement quality
• Psychological confidence

Even after returning to play, continued strength training and injury prevention work remain important.

A gradual progression back into soccer usually works best:

1. Running
2. Agility drills
3. Non-contact training
4. Controlled scrimmages
5. Full unrestricted play

Working with a physiotherapist, athletic therapist, or sports medicine professional can help ensure testing is accurate and safe.

Returning at the right time may reduce reinjury risk and improve long-term performance on the field.