What can I do to strengthen my knees?

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Strength and mobility exercises are among the most important things people with osteoarthritis can do for their knees. These exercises can relieve pain, strengthen the joints, and improve joint function. There’s no need to worry about damaging your joints if you do the right kind of exercises.

Many people who have osteoarthritis tend to avoid sports and exercise. They are afraid of putting more strain on their joints and "wearing them down" even more. But doctors now know that it's bad for the joints if they aren't used enough. There are two reasons for this:

  • Exercise increases the blood supply and the metabolic processes, and supplies the joint fluid with nutrients.
  • Exercise allows the joint fluid to enter the cartilage in the joint: The cartilage squeezes together like a sponge and releases waste products when under strain, and it absorbs nutrients from the joint fluid when released.

Doing sports also strengthens your muscles, increases the stability of your joints, and improves their flexibility. This not only protects the knee, but also helps in everyday situations – for instance, when climbing stairs or getting up from a chair.

At first your body might need to get used to regular exercise. Your joints may hurt a bit and you could develop sore muscles or feel slightly exhausted. Research shows that it's worth the effort: Regularly doing strength and mobility exercises can relieve pain and improve joint function after only a few weeks. Exercise can also make you feel good because it increases your general wellbeing, increases confidence in your own body, and helps to clear your head.

What are good exercises for osteoarthritis of the knee?

Strength and mobility exercises are particularly suitable for osteoarthritis of the knee – ideally, they should be done 2 to 3 times a week for about 45 minutes. If that’s too much at first, you can slowly work towards that.

Before doing strength exercises, it helps to warm up for 5 to 10 minutes – for example on an exercise bike or with brisk walking. It’s also recommended that you start with light exercises and slowly increase the intensity.

Exercises to strengthen leg muscles include:

Step-ups

  • Put one foot on the first step of a staircase.
  • Put the other foot on the step and then set it right back down onto the floor.
  • Continue for one minute, then change sides.
  • Hold on to the handrail for balance.

Illustration: Exercise 1: Step-ups – as described in the article

Exercise 1: Step-ups

Getting up from a chair without help

  • Sit on a chair with your knees bent at a 90-degree angle, legs slightly apart.
  • Cross your arms in front of your chest and slightly lean your upper body forward.
  • Now slowly stand up and sit back down without using your arms.
  • Repeat for a minute, then take a short break and try to keep doing the exercise for a bit longer.

It is usually possible to do more repetitions over time. The lower the chair, the harder the exercise. It is best to place the chair against a wall to make sure that it stays in place.

Illustration: Exercise 2: Standing up and sitting down – as described in the article

Standing up and sitting down

Strengthening your thigh muscles

  • Sit on a chair or stool that’s high enough for your knees to bend at a roughly 90-degree angle.
  • Wear a light weight cuff on your calf (above the ankle).
  • Slowly stretch out one leg and lift it up, hold for 5 seconds, and then slowly bend and lower it. Repeat 8 to 12 times and then do the same with the other leg.
  • Rest for about one minute and then do 2 to 3 more sets.

In the beginning, this exercise can also be done without weights.

Illustration: Exercise 3: Strengthening your thigh muscles – as described in the article

Strengthening your thigh muscles

Tensing thigh muscles

  • Sit on a chair and put your feet flat on the floor so that your thighs and calves form a roughly 90-degree angle. Then cross your calves.
  • Try to extend the lower leg while pressing the upper leg against it so that you tense your thigh muscles in both legs.
  • Tense your muscles 12 times by alternating between 5 seconds of tension and 5 seconds of relaxation, then take a short break. Repeat this set of exercises about 2 to 3 times.
  • Then cross your legs the other way and repeat.

Coordination and mobility exercises

Many specialists recommend doing coordination and mobility exercises on top of the strength exercises. One way to improve your coordination is by standing on one foot when you brush your teeth, and then stand on the other foot the next time. With time and a little practice, you might even be able to do this on your tiptoes.

What to remember

It’s important to do the exercises safely – for example, by avoiding sudden movements and using a chair or table for support when doing certain exercises that involve standing up. Wearing supportive, shock-absorbing sneakers with a good profile can also help.

If you have other medical conditions or health problems, it’s best to speak with your doctor to see if there are any reasons to avoid certain movements. One reason might be an acutely inflamed knee that is swollen and painful.

Do endurance sports help too?

Most studies looked at training programs to strengthen muscles. But there’s also some that endurance exercise such as brisk walking or cycling can help to strengthen your muscles. The same is true of tai chi.

To improve endurance, it’s best to choose low-impact sports with smooth motion sequences that move the joints but don't stress them – like brisk walking, cycling, swimming, and aqua aerobics. Sports where the joints have to absorb a lot of force and impact usually aren't recommended. Examples include jogging, tennis and soccer.

You can also combine different types of exercise. It’s then probably best to do the different exercises on different days. For instance, you could do strength and mobility exercises two days a week, and walk or cycle for 30 minutes on two other days of the week.

Who can help you find the right exercises or exercise classes?

A physical therapist or doctor – if possible in a practice experienced in osteoarthritis – can help you choose the right exercises and classes. With professional help, you can find exercises that suit your mobility and strength.

There are various sources of support:

  • Training supervised by a physical therapist
  • Special functional fitness training or rehabilitation exercise groups
  • Courses for prevention, such as tai chi. In Germany these are offered by statutory health insurers

The goal of physical therapy is to learn exercises that you can then do on your own over the long term. In Germany, doctors can prescribe up to six sessions of physical therapy for people with osteoarthritis, or more if there are medical reasons for it. A new prescription for physical therapy can be issued after six months.

Some support groups and larger sports clubs offer special group exercise classes for people who have osteoarthritis, including functional fitness training classes. These involve certain exercises or aqua aerobics that are done under the instruction of a physical therapist. The advantage: If the organizer is certified by the statutory health insurers, the costs of group functional fitness training courses are covered – usually two sessions per week for twelve months, and in certain situations for up to 24 months. Doctors can prescribe functional fitness training using a special form to ensure that it doesn’t negatively affect their budget. The same applies to rehabilitation exercises (in German: Rehasport) for improving endurance, strength, coordination and mobility. These rehabilitation exercises are offered for groups and usually include 50 classes spaced out over an 18-month period.

The statutory health insurers in Germany also offer various courses for prevention and health that would also be suitable for people with osteoarthritis – such as tai chi or courses for strengthening your muscles and joints. These kinds of courses are most suitable for people who have mild osteoarthritis. Some can also be done online. You can ask your insurer about the available courses.

How do you find the right amount of exercise?

Exercises to strengthen muscles have to be challenging – otherwise, there’s no training effect. Feeling a little temporary pain is normal. But you shouldn't have intense pain. Signs that the training is too intensive include

  • pain worse than a 5 on an individual scale from 0 (no pain) to 10 (worst possible pain),
  • pain that lasts for hours after the training, and
  • swollen joints the next day.

It's a good idea to do fewer repetitions or less strenuous exercises if you experience any of these signs. If there are problems, ask a professional whether you’re doing the exercises right or whether other exercises would be better.

Why shouldn’t you worry about pain?

Your joints may hurt at first when you start doing new exercises. Many people with osteoarthritis believe that the pain is a sign that their body is being injured. But chronic pain isn't a good indicator of the condition of a joint. A little joint pain during exercise doesn’t mean that the joints are being harmed. So you can exercise even if you have a little pain.

There are also some other reasons why pain isn't always a reliable warning sign for people with osteoarthritis: How you perceive pain strongly depends on your mood and situation. For example, if you’re exercising in a group following a teacher’s instructions, you may worry less about minor pain or not notice it nearly as much as people who exercise alone at home and are unsure of what they’re doing.

Staying active has a lot of advantages: Many studies show that physical exercise can relieve osteoarthritis pain and improve joint function. When you exercise, your body releases substances that have a pain-relieving effect. Exercise also improves blood circulation and stimulates your metabolism, making sure that your bones and cartilage get enough nutrients. It reduces the risk of falls too.

What can help you stick with an exercise routine?

It can be hard to make regular exercise part of your daily routine in the long run, and you have to be motivated to do it. For many people, signing up for classes on specific days or agreeing to exercise together with friends or partners makes it easier. Some set up reminders, pack their gym bag before work, or motivate themselves with small rewards. Fitness watches and smartphone apps are one way to keep track of your activities, set goals and stay motivated. Scheduling follow-up appointments with a physical therapist or doctor can help as well. If necessary, you could discuss ways to modify your exercise routine at these appointments.

Noticing progress after some time also makes it easier to stick with your program. Once exercise has been integrated into their daily routine, many people wouldn’t want to do without it.

What else can you do?

If you're overweight, losing weight can take some strain off your joints. In studies, losing more than 5% of the starting weight improved mobility and relieved joint pain. Losing weight and keeping it off isn't easy – it takes motivation and weeks or months of patience. But various programs can help. The best way to keep off weight you have lost is by eating a balanced diet that suits your body's energy needs, and getting enough exercise.

Wearing shoes that fit well and have thick and sturdy soles is also recommended. The shoes should support the arch of your foot and leave enough space for your toes. Tight shoes and high heels aren't suitable.

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IQWiG health information is written with the aim of helping people understand the advantages and disadvantages of the main treatment options and health care services.

Because IQWiG is a German institute, some of the information provided here is specific to the German health care system. The suitability of any of the described options in an individual case can be determined by talking to a doctor. informedhealth.org can provide support for talks with doctors and other medical professionals, but cannot replace them. We do not offer individual consultations.

Our information is based on the results of good-quality studies. It is written by a team of health care professionals, scientists and editors, and reviewed by external experts. You can find a detailed description of how our health information is produced and updated in our methods.

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Please note that we do not provide individual advice on matters of health. You can read about where to find help and support in Germany in our information “How can I find self-help groups and information centers?

Updated on August 24, 2021
Next planned update: 2024

Authors/Publishers:

Institute for Quality and Efficiency in Health Care (IQWiG, Germany)

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