Phase 4: 3–6 Months After ACL Surgery
You're now three months out from surgery. Walking should feel normal, and you're likely feeling real stability in your knee — that's a wonderful milestone, and worth pausing to appreciate. But we're still some way from our real goal: getting you back to running and sport. This is the phase where staying focused matters most.
Stay Alert
Many patients finish their hospital-based rehab around this point and slide back into the full rhythm of work or school. It's easy, without noticing, to lose sight of the end goal. This is exactly the phase where compliance makes the biggest difference to your long-term outcome — so keep your structure and your discipline going, even as life gets busier again.
Build Symmetrical Leg Strength
Aim for the gym 3 to 4 times a week, with your single-leg exercises — leg extension, hamstring curl, and leg press — as prescribed.
Do these on both legs, not just the operated one. This gives you and your physiotherapist a clear picture, right there in the gym, of what your normal leg can push, so you have a real target to work toward. The goal is symmetry — equal strength on both sides — and getting there takes close, ongoing work with your physiotherapist and strength trainer.
Muscle doesn't build overnight. Be patient with the process, and trust it.
Fuel Your Recovery
Strength training only works if you recover well between sessions. Pay attention to your protein intake, especially in the recovery window right after training — a protein shake or a glass of chocolate milk shortly after each gym session helps support muscle repair. And make sure you're getting adequate rest between training days, so your muscles have time to actually rebuild.
Build Your Aerobic Capacity
You're probably not ready to run yet, but this is the phase to start building the aerobic base that will carry you into running later. The stationary bike is your best tool here — as part of your gym warm-up, or as its own dedicated session at a sustained heart rate.
A few important cautions:
- Pace yourself. Don't ramp up your cycling duration too quickly.
- Get a proper bike fit. Ask your physiotherapist how high to set your seat. An incorrect setup can quietly load the knee through thousands of repetitive pedal strokes and cause compensatory discomfort you don't need.
In short: this phase is about two things running in parallel — building aerobic capacity through cycling, and building symmetrical leg strength in the gym.
Looking Ahead: The Six-Month Milestone
At six months, you'll return for your isokinetic strength test — the formal checkpoint that determines whether you're cleared for more aggressive jogging.
Along the way, your physiotherapist may also run a simpler 1-rep max (1RM) test in the gym. If you reach at least 70% of your uninjured leg's strength on this test, you may be cleared for some very light, gentle jogging as a supplement to your cycling — not fast-paced running, and not a substitute for the full isokinetic clearance still to come.
If you're ever unsure, err on the side of caution. Stick to the bike, keep at your single-leg strength work, and know that you're very close to being through the tunnel.
Questions about where you are in your recovery? Visit the ACL Recovery Hub for the full phase-by-phase guide.