Knee strengthening exercises

Knee pain is a very common issue. In a single year in the UK, around three in every 100 people see their GP for knee pain. Knee strengthening exercises can help both relieve and prevent knee pain. 

Is it safe for me to exercise my knee?

If you have knee pain, check with your doctor before starting any exercise programme as they will let you know if it is safe to do so. In most cases, exercising your knee will strengthen the muscles that support it, which will help your knee become stronger and more flexible, and reduce the strain placed on it. 

It is important to talk to your doctor or a physiotherapist about which exercises are appropriate for you and to gradually increase the amount and/or intensity of your exercise. 

If you have knee pain caused by surgery or an injury, gentle stretching and strengthening exercises are helpful both to reduce your pain and improve your knee’s range of motion and flexibility. 

If you have knee pain caused by arthritis, it is also important to exercise your knee to avoid stiffness, reduce knee pain and improve its range of motion. 

How to strengthen knees

There is a range of different exercises you can perform to strengthen your knees. These exercises focus not only on strength but also flexibility through stretching. Try to perform knee exercises four to five times a week.

Warm up before exercising your knee

It is important to warm up for five to 10 minutes before you exercise to reduce your risk of injury. Your warm-up exercises should be low impact eg 

• Calf raises
• Cycling on a stationary bicycle 
• Walking while pumping your arms
• Wall push-ups
• Using an elliptical machine

After warming up, you should stretch your muscles. 

Stretching exercises

After you are warmed up, performing lower body stretching exercises will improve the range of motion and flexibility of your knee joint. These stretches should also be performed as you cool down after your knee strengthening exercises.

The following three lower body stretches are effective at getting your body ready for knee strengthening exercises:

Hamstring stretch

This stretches your hamstrings (the muscles at the back of your thighs).

To start, lie on your back on the floor with both legs straight. If this is not comfortable, bend your knees and keep your feet flat on the floor. Then lift one leg off the floor, place your hands behind your thigh below the level of your knee and gently pull your knee towards your chest — only go as far as is comfortable. You should be able to feel the muscles from just below the base of your buttocks all along the back of your leg stretching. Hold this position for 30 seconds. Then place your leg back down and repeat the process for the other leg. Stretch each leg in this way twice.

Heel and calf stretch

This stretches your calf muscles (the muscles at the back of your lower leg).

To start, stand facing a wall and place your hands on the wall. Move one foot back — only go as far as you find comfortable. Make sure your feet are facing forward, your heels are flat on the floor and your knees are slightly bent.

Now lean forward into the stretch by bending your front leg. Hold this position for 30 seconds. You should be able to feel your calf muscles stretching. Now repeat the same process for your other leg. Stretch each leg in this way twice.

Quadriceps stretch

This stretches your quadriceps (the muscles at the front of your thighs).

To start, if you need support, stand next to a wall or chair. Then place your feet a shoulder width apart and bend one knee back so your heel moves towards your buttocks. Next, hold your ankle and gently pull it towards your buttocks — only go as far as is comfortable. Hold this position for 30 seconds. Place your bent leg back down and repeat the same process for your other leg. Stretch each leg in this way twice.

Strengthening exercises for your knee

Knee strengthening exercises will reduce the strain placed on your knees by strengthening your calf muscles, gluteal muscles (three muscles in your buttocks), hamstrings, hip muscles and quadriceps.

Calf raises

These will strengthen your calf muscles.

To start, stand facing the back of a chair, sofa or wall bar. Then raise your heels up and lower them back down. Do this three times, rest for a few seconds, and then repeat the whole process 10–15 times.

If this becomes too easy, try doing this with one foot raised slightly off the floor, so all of your weight is placed on your other foot. Then switch legs and repeat the process.

Half squats

These will strengthen your hamstrings, gluteal muscles and quadriceps.

To start, stand with your feet shoulder width apart and place your hands on your hips. If you find it difficult to squat like this, hold your hands out in front of you for extra balance. Then look straight ahead and slowly bend your knees. Try to bend your knees far enough so that your body lowers by about 25 cm — this is a half squat. If you find this difficult, go as far as you can. Hold your squat for several seconds and then push off through your heels until you’re standing straight again. Do this 10 times, rest, and repeat the whole process two to three times.

Straight leg raises

These will strengthen your quadriceps.

To start, lie on your back on the floor with your legs straight. Then bend one knee, keeping your foot flat on the floor. Now lift your other leg, which is straight, up to the level of your bent knee. Do this 10–15 times and repeat the whole process three times.

Hamstring curls

These will strengthen your hamstrings.

To start, lie down on your stomach on the floor. Then lift your heels towards your buttocks — go as far as is comfortable. Do this 15 times. If this becomes too easy, add ankle weights, gradually increasing the heaviness.

Leg extensions

These will strengthen your quadriceps.

To start, sit in a chair with back support and place your feet flat on the floor a hip width apart. Then while looking straight ahead, contract your thigh muscles and extend one leg as high as you can without lifting your buttocks off the chair. Hold this for a couple of seconds and gently bring your leg back down. Repeat the process for your other leg. Do this for each leg 10 times and repeat the whole process two to three times.

Leg presses

These will strengthen your quadriceps.

You will need to use a leg press machine, which can be found in most gyms. Sit on the machine with your back and head leaning against the support and your feet on the foot plate. Gradually push the plate away from you until your legs are fully extended. Then gradually bend your knees to return to the start position. Do this 10–15 times and repeat the whole process two to three times.

Prone straight leg raises

These will strengthen your hamstrings and gluteal muscles.

You will need to use a mat. Lie down on your stomach on the mat with your hands, palms down, on either side of your head. Contract your gluteal muscles and your hamstrings in one leg and lift this leg up as far as is comfortable. Hold this position for five seconds, remembering to keep your pelvis on the floor throughout. Lower your leg back down, rest for two seconds and repeat 10 times for each leg. Then repeat the whole process two to three times.

Side leg raises

These will strengthen your gluteal muscles and your hip abductor muscles (muscles on the outer sides of your hips).

To start, lie on your side with your legs stacked on top of each other. Then, using your arm that is touching the floor, cradle your head in your hand. Place your other hand on the floor in front of you. Now raise your top leg up as far as is comfortable. Hold this position for a second and lower your leg back down. Repeat this 10 times for each leg and repeat the whole process two to three times.

Step-ups

This will strengthen your hamstrings, quadriceps and gluteal muscles.

Place one foot on a raised platform about the height of a step on a staircase — if you don't have a step bench you can use the lowest step of a staircase. Your knee, hip and leg should all be aligned. Keeping your pelvis level throughout, bring the other leg up to the platform and then take it back down, lightly touching the floor with your toes. Do this 10–15 times for each leg.

Wall squats

These will strengthen your gluteal muscles, calf muscles and quadriceps.

To start, stand with your back against a wall with your feet shoulder width apart. Then slowly bend your knees, while keeping your back and pelvis against the wall. Only bend as far as is comfortable and never past 90 degrees. Hold this position for five to 10 seconds. Repeat this and try to hold the position for a few seconds longer each time.

What else can help with knee pain?

There are other lifestyle changes you can make that may ease your knee pain, depending on the underlying cause. 

Being overweight or obese is a risk factor for knee problems, including osteoarthritis. Weight loss, through following a healthy diet and exercising regularly, can therefore help ease knee pain, alongside performing knee strengthening exercises. 

If your knee pain is caused by overuse, then rest, applying ice packs for 20 minutes three to four times a day, wearing elastic compression bandages and elevating your leg can help. You may also benefit from physiotherapy — a physiotherapist can develop an exercise programme tailored to your needs, including stretches, and exercises to strengthen your muscles and range of movement in your knees.

Knee-friendly cardio

Once you have restored strength and flexibility to your knees through knee strengthening exercises, you can also try other low-impact exercises, such as:

• Stationary cycling
• Swimming, jogging in water or water aerobics
• Tai chi
• Using an elliptical machine
• Walking
• Yoga

Try to avoid high-impact exercises (eg running, jumping) as these put greater strain on your knees. 

What exercises not to do with bad knees

It is normal for muscles to be sore after exercise, however, any exercise you take part in shouldn’t worsen your knee pain.

If you experience sudden, sharp or shooting pain during or after exercise, stop and see a doctor to check your knee.

Try to avoid high-impact activities, such as running, jumping and intense aerobics, as they put greater strain on your knees.

You may need to try several different low-impact exercises until you find one that works for you and that you enjoy.