What can I do to strengthen my knees?

Photo of a couple on bikes (PantherMedia / Monkeybusiness Images)

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 with osteoarthritis avoid sports and exercise for fear of putting additional strain on their joints and wearing them out faster. But there’s no need to worry about that: In fact, lack of movement is bad for the joints. For one thing, movement is important for the metabolic processes in the joint cartilage. Also, exercise can strengthen muscles, improve joint stability, and increase range of motion. This not only protects the knee but also helps in everyday life – for example, when climbing stairs or getting up from a chair.

Even if your joints hurt, it’s usually best to keep moving. But many people who have painful and stiff joints find that hard to do. That’s why it’s very important to find the right type of exercise that you enjoy, too. Exercising in a group can help to motivate you.

Even if your body first has to get used to sports and is a little tired afterward: Studies show that it’s worth staying active. Regularly doing strength and mobility exercises can relieve pain and improve joint function after only a few weeks. Many people also feel better when they exercise because it increases your general wellbeing, increases confidence in your own body, and helps 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 two to three times a week for about 45 minutes. If that’s too much at first, you can slowly work towards that.

Before starting with 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:


  • 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 articleExercise 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 quick break and try to keep doing the exercise for a bit longer.

Over time, you can do more and more repeats. The lower the chair, the harder the exercise. It’s 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 articleStanding 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 articleStrengthening 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.
  • Press your calves together so that the thigh muscles tense 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 calves the other way and repeat.

Coordination and mobility exercises

Many specialists recommend doing coordination and mobility exercises on top of the strength exercises. To improve coordination, you could, for example, stand on only one leg while brushing your teeth, and then switch legs. Once you get a little practice, you might even stand on your tiptoes.

What to remember

It’s important to do the exercises safely – for example, by avoiding jerky movements and using a chair or table for support when doing certain exercises. 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. If you have an acutely inflamed knee that’s swollen and painful, exercises aren't advisable without first talking to a physical therapist or doctor.

Do endurance sports help too?

Most studies looked at training programs to strengthen muscles. But there’s also some evidence that endurance exercises such as brisk walking can help. The same is true of tai chi. Endurance sports like cycling also strengthen muscles to some degree.

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 walking, cycling, swimming, and aqua aerobics. Sports where the joints have to absorb a lot of weight and impact, like jogging, tennis, or soccer, are usually not recommended.

You can also combine different types of exercise. It’s then probably best to do the different exercises on different days: for example, 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 me 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.

Support groups are good places to turn to too. They often organize special training groups for people with osteoarthritis, including functional fitness training: exercises or aqua aerobics that are done under the instruction of a physical therapist. The advantage: German statutory health insurers will pay for 12 months of group functional fitness training held twice a week, and under certain conditions it may pay 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.

How do I 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 feel 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.

If you have any of these signs, you should do fewer repetitions and sets of exercises or try easier exercises. 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?

Joints can hurt, especially when you first start exercising. Many people with osteoarthritis believe that pain is a sign that the body is being injured. But chronic pain isn't a good indicator of the condition of a joint. It’s the same as with X-rays: Even easily visible, severe joint damage doesn’t always hurt, and some people have really bad pain without any visible changes on the X-rays. 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 good adviser 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. Exercise 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 rewards. Electronic devices like step counters (pedometers) are sometimes helpful too. 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.

Noticeable 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 I 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 requires motivation and weeks or months of patience. But various programs can help.

It is also recommended that you wear well-fitting shoes with shock-absorbing soles. Shoes should support the arch of your foot and leave enough space for your toes. Tight shoes and high heels aren't suitable. There’s no proof that special pain relief shoes ("unloading shoes") have any benefits.