Episode 281 | Is Knee Soreness Normal in ACL Rehab?

What is up team? And welcome back to another episode on the ACL Athlete Podcast. Today, I want to talk about a particular comment or piece of feedback I get from many of my ACL athletes, and that is: “My knee feels sore.” We’re talking about soreness, not specifically pain. They just say their knee feels sore. So picture this: you get through a solid session. Maybe some split squats are in there, some single-leg work, some dynamic work. Maybe it’s a change of direction, maybe it’s jumping. You feel strong walking out of the gym or out of your session.

Then a few hours later, you’re sitting on the couch, and you notice that soreness. Your knee feels a little different. It’s not your quad necessarily, it’s not your hamstrings. It’s the joint itself, right at the front of the joint, or maybe it’s just the knee in general, maybe a little bit behind the kneecap. It’s talking louder than it was during the session or even an hour ago.

That’s usually when a spiral can start, especially if you’ve been in this process and have dealt with setbacks or flare-ups in the knee. There can be this thought of, “Did I do too much? Did I just undo months and months of progress?” Especially if you just got out of a flare-up and now you’re wondering if this session flared it up again. You’re asking yourself, “Is this the start of a setback?”

You start gathering information. Maybe you message your physical therapist. Maybe you can bring it up in your next session. Maybe you pull up Google or an AI and type in whatever you’re experiencing. The answers are all over the place. One result might suggest you’ve torn your ACL again. Another says it’s a cyclops lesion. Another says it’s normal and you should push through it. And if you start digging through Reddit or Facebook groups, you can really end up down a rabbit hole. Now you’re lying in bed, feeling the soreness and trying to process what it means.

I want to talk through this today because situations like this happen all the time. Every single ACLer going through this process experiences these moments, and many of you experience them more than once. Your knee is going to get sore.

I know that’s sometimes hard to describe because you’re not saying it’s painful or even stiff. It just feels sore. Like after a hard workout when your muscles are sore, except it’s the joint itself. It could be in the front of the knee, or it could feel like the entire joint. It’s often difficult to describe, especially when it isn’t pain specifically.

The first thing I need you to hear before anything else is that sore is not the same thing as pain. The joint is not the muscle. In the vast majority of cases, what you’re feeling is not the disaster scenario you’ve played out in your head or the one you’ve read about online. This is where the nuance matters. Soreness is normal, but we do need to look more closely at it to determine whether it’s something that deserves attention or something we simply monitor and let ride. I want to give you some practical strategies around this.

Let’s first get specific about what we’re actually talking about. Muscle soreness could be in your quads, hamstrings, glutes, or calves. That’s the soreness we’re generally aiming for because we’re trying to rebuild those muscle groups. The soreness tells us those tissues received a stimulus, and that’s helpful.

Now, just because you’re not sore in your muscles doesn’t mean they weren’t worked. When you’re in a new training block or doing new exercises, soreness tends to show up more. If there’s more eccentric work, where the muscle is lengthening under load, you’re likely to feel it even more. As your body adapts, though, that soreness often decreases even while progress continues. You don’t need to wake up sore every day for training to be effective.

The real focus here is joint soreness, which is different. That’s the knee itself. The joint line. The front of the knee. Most ACLers know this feeling. It’s your knee telling you it’s adapting to something. The important thing to understand is that this can show up at different stages of rehab for very different reasons.

Early on, your knee is relearning how to handle load. After the injury and surgery, the knee is in a sensitive state. You’re rebuilding after two significant traumas, and the joint’s capacity has been reduced. Think about someone who could comfortably run ten miles, takes months off, and then tries to run again. They’re not starting at ten miles. They may respond to one or two miles. The same concept applies here.

The floor has been lowered. Your knee’s tolerance is reduced, so you’ll notice things at lower thresholds. Early joint soreness is often your knee recalibrating and relearning how to handle movement and stress again.

Later in the process, when you’re lifting heavier, building power, and performing more demanding dynamic movements, your joints are going to talk more. That soreness can show up again. It’s not a red flag. If we’re talking about increasing pain and swelling, that’s different. But soreness by itself is not a red flag. It’s barely even a yellow flag.

The reality is that this is often the cost of doing the work that gets you back to sport. The further you get into rehab, the more normal it becomes to notice joint soreness because you’re asking more of your knee. Many athletes assume that once they’re past the early post-op phase, the knee should never react to anything again. But you’re loading it more. You’re moving faster. You’re decelerating, accelerating, sprinting, cutting, and changing direction.

All of those forces have to go somewhere. They go through the knee, through the muscles, through the tendons, and through the graft site if you have one. That’s why strength matters so much. If the muscles aren’t strong enough to absorb the load, the joint often ends up taking more of it.

A good example is landing from a table. If you land with stiff, straight legs, your joints take the brunt of the force. It feels terrible. But if you land with bent knees and allow your muscles to absorb the impact, the force gets distributed much more effectively. That’s why we care so much about restoring quad strength and improving the ability to tolerate braking forces. Strong muscles act as shock absorbers and help disperse stress throughout the system instead of concentrating it in the joint.

Even when you’re doing everything right, higher-impact activities place more demand on the knee. The further you progress and the closer you get to your sport, the more you’ll notice this. Sports involving cutting, jumping, sprinting, skiing, or climbing all place unique demands on the knee that can’t be perfectly replicated in the gym.

Here’s what most people get wrong. They feel soreness and immediately panic. Their first instinct is to stop everything, rest, and assume something is wrong. Others go to the opposite extreme and try to push through no matter what. Usually, the best answer lies somewhere in the middle.

The key is to identify what you’re feeling without panicking. Name it. Track it. Treat soreness as information. After my second ACL reconstruction, any sensation in my knee immediately triggered worst-case-scenario thinking. I dealt with significant kneecap pain, which I now believe was related to poor rehab decisions and load management at the time. That experience made me hyperaware of every sensation.

It took time, good coaching, and experience to learn the difference between my knee talking to me and my knee yelling at me. Once I learned that distinction, I stopped panicking every time something felt off. That’s a lesson I’ve continued to apply through other injuries, surgeries, and even my recent hip procedure.

Let’s break down where soreness actually comes from, because not all soreness has the same cause.

The first source is early-stage load reintroduction. If you’ve been non-weight-bearing, restricted in a brace, recovering from a meniscus repair, or simply haven’t been moving much, your knee is going to respond when loading returns. Capacity drops quickly after ACL injury and surgery. Strength declines rapidly, especially in the quads. The nervous system also changes significantly after this injury. Things shut down. The body protects itself. When movement returns, some soreness is expected.

The second source is entering a new phase, a new block, or introducing new movements. Any time you expose your knee to a new stressor, there’s an adjustment period. Maybe you’re introducing deceleration work, box drops, or new eccentric-focused exercises. These places new demands on both the muscles and the joint. The knee hasn’t adapted to that specific stress yet.

This is where the SAID principle comes in: Specific Adaptations to Imposed Demands. The body adapts specifically to what it’s exposed to. If a movement is new, adaptation takes time. That’s why we build what I call a launch week into every new block. Instead of going all-out immediately, we intentionally ease into the new training stimulus. We let the knee show us how it responds before increasing intensity.

This is one of the qualities that separates great rehab professionals and coaches. Every exercise should have regressions and progressions readily available. Good coaching isn’t about forcing athletes into a specific exercise. It’s about adapting movements to the athlete and meeting them where they are while continuing to build toward higher-level demands.

The third source is load mismanagement. This is probably the one most people miss. I’ve talked before about the value of a high-low approach. Maybe Monday, Wednesday, and Friday are high-demand days, while Tuesday, Thursday, and Saturday are lower-demand recovery days. This allows you to train hard when needed and recover appropriately.

Problems often arise when people stack demanding days together without enough recovery. Maybe they increase their step count dramatically while traveling. Maybe they’re doing intense strength sessions, running, and sport work all within a few days. The cumulative load starts adding up.

It’s rarely one bad session that creates problems. More often, it’s multiple days of accumulated stress without enough recovery. If I had to guess which of these factors causes the most unnecessary setbacks, it would be load mismanagement.

What should you do when soreness shows up?

First, give it 24 hours. Soreness after a session is normal. The real question is what it looks like the next day. Is it improving? Staying the same? Getting worse? That 24-hour feedback loop tells us a lot.

Second, ask yourself whether the knee is whispering, getting louder, or yelling. A little soreness that settles down is probably just a whisper. Soreness that continues building over multiple sessions is getting louder. That’s when it deserves more attention.

Think of it like a traffic light. Green means it’s there but improving. Continue as planned. Yellow means it’s hanging around or becoming more noticeable. Back off slightly and monitor it. Red means it’s getting louder across multiple sessions or changing how you move. That’s when it’s time to talk with your coach or physical therapist and adjust the plan.

The important thing is to be proactive. Don’t wait until things are clearly in the red zone. If it’s moving from a whisper toward something louder, that’s usually a good time to communicate and troubleshoot.

One final point: in the mid and late stages of rehab, stress on the knee should be increasing. That’s actually evidence that the plan is working. The mistake many athletes make is how they introduce that stress. They come off a deload, feel great, and immediately go from zero to one hundred.

Your knee almost always lets you know when it doesn’t appreciate that approach.

Instead, use a dimmer switch. Ease into new movements and new demands. That’s exactly what launch week is designed to accomplish. It’s not a throwaway week. It’s a week for gathering feedback and allowing the knee to adapt before pushing harder.

I often use the undercook-versus-overcook analogy. If you had a steak, would you rather undercook it or overcook it? Most people would choose undercooked because you can always put it back on the grill. The same applies here. You can always add a little more next session. But if you overcook the knee and it starts yelling at you, now you’re stuck waiting for it to calm down.

So here’s what I want you to take away.

Soreness in the joint during ACL rehab is normal. In fact, it’s often more common as you progress further into the process, not less. Pain and swelling belong in a different category. We’re talking specifically about soreness.

As the knee rebuilds its capacity, you’re raising both the floor and the ceiling of what it can tolerate. Along the way, soreness is often part of that process. Managed well, it becomes a few uncomfortable days that fade away as you continue progressing. Managed poorly, ignored, or pushed through recklessly, it can evolve into pain, swelling, stiffness, and setbacks that linger for weeks.

The next time you feel soreness, don’t spiral. Ask yourself one question:

“Is this whispering or is this yelling?”

That one question will tell you almost everything you need to know about what to do next.

And if you want to learn more about how we program for athletes, or if you need help navigating your own ACL rehab, reach out. We are here to help.

That’s going to do it for today. This is your host, Ravi Patel, signing off.