ACL Rehab a Year Later: What Still Needs Testing Before Sport — Muscle IQ in Orem

It has been about a year since your ACL surgery. Your strength numbers looked close to even, and you were cleared to return. And yet the first pickup game, the first ski run, or the first hard cut on a soccer field in Orem feels like it needs a little more thought than it used to.

If that sounds familiar, that hesitation is common and worth taking seriously. A strength number is only one part of what a knee has to get back.

Why "Strong Enough" Can Still Miss Something

Most return-to-sport decisions lean on one comparison: how strong is the surgical leg next to the other leg? Reaching 90% of the other leg is a common benchmark for being ready. It is a reasonable starting point. It has one weak spot: it assumes the other leg is a clean reference.

A 2024 meta-analysis in Physiotherapy Theory and Practice pooled 14 studies and 381 people with ACL injury or reconstruction. In lab testing that uses magnetic stimulation over the brain, the pathway to the thigh muscle needed more stimulation to respond in people with ACL injuries than in healthy controls. That was true on the uninjured side too. The studies were observational, so they cannot say the injury caused the change.

This is why we ask the question. If both legs may be starting below their own normal, being 90% of the other leg does not necessarily mean 100% of you.

A Muscle Can Test Strong and Still Be Turned Down

In one small 2022 study in the European Journal of Sport Science, Schilaty and colleagues measured individual motor units (the nerve-and-muscle teams that make a muscle contract) in ACL-injured athletes. The injured thigh showed lower firing rates and smaller motor units than controls, while hamstring activity was higher. Those differences could persist up to 12 months after surgery, even as maximal strength improved.

A 2010 systematic review in the Journal of Athletic Training by Hart and colleagues looked at how fully patients could activate the thigh muscle. On average, activation after ACL injury and reconstruction was lower than in healthy controls, and the uninvolved leg was often affected too.

One way to picture it is the muscle tone dial. Pain, swelling, and irritated tissue can turn the dial down, and part of the weakness may be a muscle that has not been fully switched back on. Strength is a number. Control is a pattern.

What a Year-Out Knee Still Deserves Checked in Orem

A year out is not too late to look. A 2025 clinical review in the Journal of Orthopaedic & Sports Physical Therapy by Vitharana and colleagues describes ACL rehab as two jobs: restoring the knee's own sense of where it is, and restoring the muscle's drive.

At Muscle IQ Physical Therapy in Orem, a year-out knee check asks four questions. How fully is the thigh muscle turning on? Is the other leg a fair comparison? How does the knee respond to unexpected demands? And is anything else in the body quietly holding the muscle back? You can read more on our knee pain page, in our post on why an ACL knee can test strong and still not feel ready, and on how we think about muscle inhibition.

Take control of your health today by calling Muscle IQ at (801) 310-0851 to schedule your first appointment.

An Honest Note on the Evidence

These studies describe groups of people, not any one knee. They are observational, the samples are small, and two of them were reviewed from abstracts. None of them shows that a specific test or treatment changes outcomes, and your surgeon's guidance always comes first. What they do support is a simple idea: before sport, a knee deserves a closer look than a single strength comparison.

Where to Start

Finding what is holding the muscle back is the first step. The sooner you get in, the sooner you can be pain-free.

Take control of your health today by calling Muscle IQ at (801) 310-0851 to schedule your first appointment.

Learn more at MuscleIQ.com.