A stronger leg before surgery can make the first difficult days afterwards more manageable. Getting out of a chair, using crutches, climbing a step and beginning rehabilitation all rely on muscles that may already have weakened because of pain or reduced activity. The best exercises before knee surgery are not about pushing through discomfort or achieving a fitness milestone. They are carefully chosen movements that maintain strength, mobility and confidence without aggravating the joint.
For many people preparing for a knee replacement, ACL reconstruction or another knee procedure, this period is known as prehabilitation. A personalised plan can help you arrive for surgery in the best possible condition while giving you a clearer understanding of the exercises you will continue during recovery.
Why exercise before knee surgery can help
Knee pain often creates a difficult cycle. You move less because the joint hurts, then the quadriceps, hamstrings and hip muscles become weaker. The knee may feel less stable, everyday tasks take more effort, and recovering after surgery can feel more demanding.
Appropriate pre-operative exercise aims to interrupt that cycle. It can help preserve thigh and hip strength, maintain the ability to fully straighten and bend the knee where this is safe, and improve balance and walking tolerance. General fitness matters too. A person who can move confidently with an aid before surgery is often better prepared for the practical demands of early recovery.
That does not mean every patient needs the same programme. Someone with severe bone-on-bone arthritis may need a gentler approach than an active person awaiting ACL reconstruction. A knee that is significantly swollen, hot, locked or unstable needs clinical assessment rather than a more ambitious exercise routine.
Best exercises before knee surgery: start with the basics
The following exercises are commonly used in prehabilitation. They should be comfortable enough to perform with controlled movement. Mild muscle effort is expected; sharp pain, increasing joint pain, giving way or swelling later that day are signs to stop and seek advice from your clinician or physiotherapist.
Quadriceps sets
The quadriceps are the large muscles at the front of the thigh. They are essential for straightening the knee, standing from a chair and controlling the leg during walking.
Sit or lie with the leg straight and supported. Tighten the front thigh muscle by gently pressing the back of the knee down towards the bed or floor. You may see the kneecap draw slightly upwards. Hold for five to ten seconds, then relax fully. Repeat little and often during the day.
This simple exercise is particularly useful if pain has made it hard to activate the thigh muscle properly. It is low impact and can usually be adapted even when weight-bearing exercise is limited.
Straight-leg raises
If you can tighten the quadriceps without pain, a straight-leg raise adds a little more challenge. Lie on your back with one knee bent and the affected leg straight. Tighten the thigh first, then slowly lift the straight leg a short distance from the surface. Pause, lower with control and relax.
The key is quality, not height. If the knee bends as you lift, return to quadriceps sets first. Some patients find this uncomfortable after certain injuries or when the hip is painful, so it should be tailored to your diagnosis.
Seated knee straightening
Sit upright in a supportive chair with both feet on the floor. Slowly straighten the affected knee until the leg is as straight as is comfortable, hold briefly, then lower it in a controlled way. This builds quadriceps strength through movement and can help retain the extension needed for an efficient walking pattern.
For some people, adding a light ankle weight may be appropriate, but only when advised. More load is not automatically better before surgery. Irritating an arthritic or inflamed knee can set progress back.
Sit-to-stands
Standing up from a chair is one of the most useful functional exercises before knee surgery. Choose a firm, stable chair, ideally with arms nearby for support if needed. Place your feet under your knees, lean forwards slightly from the hips and stand using both legs. Sit down slowly rather than dropping back into the chair.
This movement works the thighs, hips and trunk while rehearsing an activity you will need after surgery. Begin with a higher chair if the knee is stiff or painful. As control improves, reduce reliance on your hands, but do not force this if it causes a flare-up.
Heel slides and gentle knee bends
Maintaining knee movement can be valuable, especially when stiffness is a concern. Lying on your back, slide your heel towards your bottom to bend the knee, then slowly slide it away again. A towel under the heel or a smooth surface can make this easier.
Move only within a tolerable range. A stretching sensation is common, but forcing the knee into a painful bend is unlikely to help. If you are awaiting a knee replacement, your specialist may prioritise maintaining extension, or the ability to straighten the knee, as well as flexion.
Calf raises and ankle pumps
The lower leg should not be overlooked. Holding a kitchen worktop or the back of a sturdy chair, rise slowly onto the balls of both feet and lower again. This maintains calf strength and ankle control for walking.
Ankle pumps are even simpler: move the feet up and down rhythmically while sitting or lying down. They are useful when you have been inactive and can become a familiar part of your early post-operative routine. They do not replace individual advice about blood clot prevention, but regular gentle movement is generally helpful when permitted.
Hip strengthening and balance work
A knee does not work in isolation. Strong hip muscles help control the position of the leg during standing, walking and stair use. Side-lying leg lifts, standing side steps while holding support, or a small bridge exercise may be suitable depending on your symptoms and balance.
Balance work should be cautious. Practising standing with feet close together beside a kitchen worktop can be enough for some patients. Avoid unsupported single-leg balance work if the knee gives way, you feel dizzy, or you are at risk of falling.
How often should you exercise?
A manageable routine completed consistently is more useful than an exhausting session once a week. Many people do mobility and muscle-activation exercises daily, with strengthening work on most days of the week. Your starting point depends on pain, swelling, fitness, the type of surgery planned and how long you have before the operation.
As a practical guide, begin with a small number of controlled repetitions and assess how the knee responds over the following 24 hours. If symptoms settle quickly, you may gradually add repetitions. If the joint becomes more swollen or painful, reduce the range, repetitions or resistance and discuss it with your clinician.
Low-impact aerobic exercise can also have a place. A static bike with minimal resistance, swimming, or gentle walking may support general conditioning if they do not worsen symptoms. For some people with advanced arthritis, a bicycle is comfortable while walking is not. For others, bending the knee on a bike is too painful. The right choice is the activity your knee tolerates best.
Exercises and activities to approach carefully
Prehabilitation should leave you feeling prepared, not depleted. High-impact running, jumping, deep squats, twisting sports and heavy leg presses may aggravate an unstable, arthritic or damaged knee. They are not essential to prepare well for surgery.
It is also sensible to avoid starting an unfamiliar, demanding programme in the final days before your procedure. A muscle strain, fall or significant swelling can complicate plans. Focus instead on steady, controlled movement, good sleep, sensible nutrition and following the instructions given by your surgical team.
When personalised advice matters most
Exercise needs to reflect the reason for surgery. Before ACL reconstruction, the priorities often include reducing swelling, restoring full knee straightening, regaining a good walking pattern and strengthening the quadriceps and hamstrings. Before partial or total knee replacement, managing pain while maintaining movement and leg strength may take priority. Previous surgery, hip or back pain, diabetes, neurological conditions and balance difficulties can all change the plan.
At Droitwich Knee Clinic, consultant-led assessment can clarify the diagnosis and help create a rehabilitation plan that fits your knee, lifestyle and planned treatment. That clarity matters: exercising the wrong way is rarely helpful, while the right level of preparation can give you a more confident starting point.
Contact your clinical team promptly if you develop new calf pain or swelling, marked redness or heat around the knee, fever, sudden loss of movement, repeated giving way, or pain that is severe and different from your usual symptoms.
The most useful preparation is not perfection. It is arriving at surgery with the strongest, safest movement you can achieve, a realistic plan for recovery, and the confidence to ask for help when your knee tells you something is not right.