ACL injury exercises: early rehab and prehab by stage

Published October 14, 2026 · Updated November 1, 2026 · Protocol Archive Editorial

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ACL injury exercises: early rehab and prehab by stage

Talk to your doctor first. General education, not medical advice.This content is general education, not medical advice, diagnosis or treatment. Get approval from your physician or another qualified healthcare provider before starting any exercise program, especially if you have a medical condition, a recent injury or surgery, are pregnant, or take medication. Stop and seek medical advice if an exercise causes pain, dizziness, chest discomfort or shortness of breath. You choose to exercise at your own risk. Read the full medical disclaimer.

Last checked: October 2026 · Protocol Archive Editorial · General information, not medical advice

The anterior cruciate ligament (ACL) runs through the middle of the knee and helps keep it stable when you twist and turn. It is most often injured during pivoting, cutting or jumping. Many people hear a pop, notice swelling within a day, and feel the knee give way.

Not every ACL injury needs surgery. NHS guidance notes that many partial tears settle with rehabilitation, and that physical therapy is needed whether or not you have an operation. If the knee is still unstable after a full course of rehab, a reconstruction may be offered.

Exercise before any surgery decision, often called prehab, aims to calm pain and swelling, get the knee fully straight, and rebuild strength and balance. NHS physiotherapy teams say this may help the knee recover better and more quickly, whichever route you take.

Get it checked first. Get a suspected ACL injury assessed by a clinician first, because other parts of the knee, such as the meniscus or other ligaments, are often hurt at the same time. If you have had ACL reconstruction, your surgeon’s and physical therapist’s protocol comes first; use this page only alongside it.
On this page

  1. Stage 1: Settle the knee and restore movement
  2. Stage 2: Build strength around the knee
  3. Stage 3: Single-leg strength and balance
  4. Videos
  5. What to expect
  6. When to get help
First days to weeks (while pain and swelling are high)

Stage 1: Settle the knee and restore movement

Reduce swelling, get the knee fully straight, regain bend, and switch the thigh muscle back on.

  1. Heel Prop for Knee Straightening

    Getting the knee fully straight is a priority early on. Compare with your other knee.

    Typical dose: Rest the heel on a rolled towel and gently tighten the thigh, 5-second holds, 10 reps, 2–3 times a day1,2

  2. Heel Slides

    Use a towel around the shin or your hands to help the bend if needed.

    Typical dose: Bend as far as comfortable, hold 5 seconds, 10–15 reps, 2–3 times a day, as pain allows1,2

  3. Quad Sets (Quadriceps Setting)

    A simple way to wake up the quadriceps, which weaken quickly after a knee injury.

    Typical dose: Tighten the thigh to press the knee down, hold 5–10 seconds, 10 reps, a few times a day2,8

  4. Supported Leg Raise

    Keep the knee locked straight as you lift. If the knee bends, go back to quad sets for a few more days.

    Typical dose: Lift the straight leg about 6 inches (15 cm), 3 sets of 8–12, until the thigh feels lightly tired1,2

  • For the first 24–48 hours, keep the leg raised when you can. After that, avoid long spells of sitting still.2
  • If you cannot walk without a limp, crutches may help until your walking improves.1,2
  • A compression bandage or sleeve can help control early swelling, but it is not meant to support the knee long term.2
Once your knee straightens and bends fully

Stage 2: Build strength around the knee

Rebuild the thigh, hamstring, hip and calf muscles so both legs work evenly.

  1. Knee Curl Strength Exercise

    Strengthens the hamstrings, which help control the knee. After surgery with a hamstring graft, check timing with your surgical team.

    Typical dose: Hold 5 seconds at the top, 3 sets of 8–12, 2–3 times a week; add a light ankle weight or band when easy1,2

  2. Bridge Pose for Glute Activation

    Works the glutes and hamstrings together. Progress to a single-leg version when it feels easy.

    Typical dose: 3 sets of 8–12, 2–3 times a week1,2

  3. Toe Stand Strength Exercise

    Strong calves help support the knee when you walk, land and change direction.

    Typical dose: Up to 20 reps or until the calves feel tired, 2–3 times a week; progress from two legs to one1,2

  • Strength sessions 2–3 times a week are typical, working until the muscles feel lightly tired rather than exhausted.1,2
  • Up to 30 minutes of low-impact cardio, such as a stationary bike or cross-trainer with little resistance, is commonly added. Increase resistance gradually.1,2
When stage 2 feels controlled and the knee stays settled the next day

Stage 3: Single-leg strength and balance

Train strength and control on one leg, and improve the knee’s position sense (proprioception).

  1. Split Squat

    Keep the front knee in line over your second toe.

    Typical dose: 3 sets of 8–12, 2–3 times a week; add hand weights later1

  2. Step-Ups

    Step up slowly with control and do not let the knee drift inward.

    Typical dose: Hold 5 seconds at the top, 3 sets of 8–12, 2–3 times a week; progress to a higher step1

  3. Stand on One Foot Balance Exercise

    Balance work trains joint position sense and is part of NHS ACL programs.

    Typical dose: 3 holds of 15 seconds, building to 30–60 seconds; then try eyes closed or head turns1,2

  • Jumping and hopping are added only once strength and control of the knee are returning. Ask your physical therapist when and how to start.1,2

Want this as a checklist? Turn these exercises into a printable home program with videos and daily check-offs. Adjust the list and doses with your clinician.

Make it a home program

Printable handout (PDF, 2 pages). Every exercise on this page with a usual starting amount, boxes for your clinician to write your plan, a pain guide and a 6-week tracker.

Download PDF A4 size Large printEn español: PDF · A4

Watch the exercises

Every exercise above links to its own page with a video and step-by-step instructions. Here are two to start with.

Play video
Heel Prop for Knee Straightening. Full steps, cues and safety notes: Heel Prop for Knee Straightening page.
Play video
Knee Curl Strength Exercise. Full steps, cues and safety notes: Knee Curl Strength Exercise page.

What to expect

These are what published guidance usually says. Your own recovery may be faster or slower.

Question What sources say
Before starting strength work Aim for full knee movement first, especially full straightening.1,2
When to move up a stage When the current exercises feel controlled and your knee is not more painful or swollen the next day. Moving on too soon can increase pain and swelling.1,2
Normal soreness Some soreness during exercise and mild muscle ache the next day are common. If knee pain or swelling increases, cut back the reps or sets.1,2
If the knee keeps giving way Whether surgery is advised depends on things like how unstable the knee feels, your activity goals and any other damage in the knee. If the knee is still unstable after completing rehab, ACL reconstruction may be offered. Discuss this with your clinician.3,4
Return to pivoting or jumping sports One NHS trust advises that rehab for these sports is likely to take at least a year. Your clinician will guide this.3

What to avoid or change for now

  • Pivoting, cutting or jumping sports until a clinician has assessed your knee and cleared you.
  • Pushing through exercises that leave the knee more painful or swollen the next day.
  • Long periods of sitting still once the first couple of days have passed.
  • Doing exercises your surgeon has restricted after ACL reconstruction, such as bending past brace limits or early loaded hamstring work after a hamstring graft.

When to get help

  • Your knee is locked or blocked and you cannot fully straighten it. Get urgent care the same day (urgent care or the emergency department).5,6
  • You cannot put weight on the leg. Get urgent care the same day.5,6
  • A large amount of swelling appeared within 1–2 hours of the injury. Get urgent care the same day.5
  • Your knee gives way and makes you fall.5
  • Numbness or pins and needles in the leg below the knee. Get urgent care the same day.5
  • Fever, or feeling hot and shivery, with redness or heat around the knee, which can mean infection. Get urgent care the same day.6
  • Throbbing or cramping pain and swelling in one calf or thigh, sometimes with red or darkened skin, can be a blood clot. Get medical help the same day, and call 911 if you also feel short of breath or have chest pain.7

For a medical emergency, call 911 (US and Canada), 999 (UK), 000 (Australia) or 112.

Next steps

Related guides: Meniscus tear, MCL sprain, Patellar tendinopathy (jumper’s knee), or see all conditions.

Need a physical therapist? How to find one in the US or UK, including direct access and checking registration.

More exercises: browse the free exercise library, every one with a video.

Had ACL reconstruction surgery? See exercises after ACL reconstruction, stage by stage.

Frequently asked questions

Can an ACL tear heal without surgery?

Not every ACL injury needs surgery. NHS guidance says many partial tears settle with rehabilitation, and reconstruction may be offered if the knee stays unstable after a full rehab program.

What is ACL prehab?

Prehab is exercise done after the injury and before any surgery. It aims to reduce swelling, restore full movement and build strength and balance, which NHS physiotherapy teams say may help recovery whichever route you take.

Should I do these exercises after ACL surgery?

Only as your surgeon and physical therapist direct. After reconstruction, their protocol sets which exercises you do, how far you can bend, and when you can drop crutches or a brace.

How long does ACL rehab take?

It varies. For people returning to pivoting or jumping sports, one NHS trust advises that rehab is likely to take at least a year.

Is it normal for my knee to ache after exercise?

Some soreness during exercise and mild muscle ache the next day are common. Your knee pain and swelling should not be worse the next day; if they are, do fewer reps.

Sources

  1. Royal United Hospitals Bath NHS Foundation Trust: ACL prehabilitation booklet (PHY034)
  2. North Cumbria Integrated Care NHS Foundation Trust: Prehabilitation programme for an anterior cruciate ligament (ACL) injury
  3. North Tees and Hartlepool NHS Foundation Trust: Anterior cruciate ligament (ACL) injury
  4. AAOS OrthoInfo: Anterior cruciate ligament (ACL) injuries
  5. East Lancashire Hospitals NHS Trust: Traumatic knee injury
  6. NHS: Knee pain
  7. NHS: DVT (deep vein thrombosis)
  8. Sandwell and West Birmingham NHS Trust: Physiotherapy: anterior cruciate ligament (ACL)

Last checked October 2026. Found something out of date? Email hello@protocolarchive.com.

This guide summarizes published hospital, health-service and professional-body advice listed under Sources. It is general information, not medical advice, and does not replace an assessment by your own clinician, whose plan may differ for good reasons. Stop an exercise and get advice if it causes sharp or worsening pain. Protocol Archive is independent and is not affiliated with the NHS, AAOS or any hospital or video publisher named on this page.

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