This Exercise Is the Best for Knee Arthritis

Osteoarthritis (OA) is a progressive degenerative joint disease that involves the breakdown of tissues inside and around the joint. Osteoarthritis is the most common type of arthritis, and it typically affects people over 45, though it can also show up in younger people, usually due to genetics, abnormal joint structure or injury. 

Osteoarthritis typically targets the knees, hips, low back, hands and neck, and women are more likely than men to get it, especially after menopause. If you have OA, you know how it can affect quality of life due to pain, causing a change in activities.

Exercise is often a first-line treatment for osteoarthritis. Medical practitioners may prescribe any number of exercises, from cardio (aerobic) exercise and strength training to yoga and stretching—or a mix of any of them. But which ones are the most effective at combating joint pain and improving function? That’s what researchers wanted to know, too, so they did a large systematic review and meta-analysis. The previously published studies included in the review included a total of over 15,500 adults. They published their findings in the BMJ. Let’s break down what they found.

How Was This Study Conducted?

Researchers searched databases for studies specifically on knee osteoarthritis. To be included in this review, the studies also had to be randomized controlled trials that used participants with symptomatic knee osteoarthritis diagnosed via X-ray, MRI or examination. Symptomatic means that the participants had symptoms that may include pain or a change in the way they walk (gait) or function. 

The studies also had to have used a control group that either did no exercise or performed a different form of exercise than the main exercise group. In addition, the studies also had to have considered the following outcomes: function, pain, quality of life, gait performance and adverse events (like falls). Studies that included people who had knee surgery or who had hip osteoarthritis in addition to knee osteoarthritis were excluded from this review.

After weeding out the studies that did not meet their criteria, researchers ended up with 217 randomized controlled trials that included a total of over 15,500 participants. Researchers conducted statistical analyses, taking into consideration the type of exercise, the duration of each study, and the main outcomes measured. 

The types of exercises included aerobic, flexibility, neuromotor (aka functional exercise, including body-weight exercises), mind-body, strength training and mixed (a combination of two or more). The primary outcomes researchers were looking at included pain, function, gait performance and quality of life, which were assessed at three different time points for follow-up: short-term (4 weeks), mid-term (12 weeks) and long-term (24 weeks).

In addition, researchers also used a specific framework to determine the degree of certainty each result held: low, moderate or high. 

What Did This Study Show?

After running several statistical analyses, researchers found that aerobic (cardio) exercise, like walking, cycling and swimming, seems to have the greatest overall benefits for knee osteoarthritis. This includes improvements in pain, function, gait performance and quality of life, all with moderate certainty (except function, which was low certainty).

But this doesn’t mean the other forms of exercise had no benefits. They also found:

• Mind-body exercise may result in a large increase in function at short-term follow-up; moderate certainty
• Neuromotor exercise may result in a large increase in gait performance at short-term follow-up; moderate certainty
• Strengthening and mixed exercise may result in a large increase in function at mid-term follow-up; moderate certainty
• Flexibility exercise may result in a large reduction in pain at long-term follow-up; low certainty
• Mixed exercise may increase function (low certainty) and probably increases gait performance (moderate certainty) at long-term follow-up

Researchers note a few limitations to this review as it relates to the included studies. First, because they only included knee osteoarthritis, it is unknown if these results apply to osteoarthritis in other joints or to other types of arthritis, like rheumatoid arthritis. This study also lacked direct head-to-head comparisons of specific types of exercise (most were comparisons between exercise and the control group), which may have influenced results; for this reason, researchers state that they should be interpreted with caution. Most of the studies also did not include certain demographics, like socioeconomic status, which could act as a confounding factor.  

How Does This Apply to Real Life?

Though osteoarthritis can show up at any age, the risk increases the older we get. According to the World Health Organization, the rate of osteoarthritis worldwide increased 113% from 1990 to 2019, with 528 million people living with the condition. Out of those, 365 million have osteoarthritis in a knee. 

While the risk goes up as we age, osteoarthritis is not necessarily an inevitable consequence of aging. And as with any disease, prevention includes a balanced diet, engaging in regular physical activity, dealing with stressors and getting plenty of quality sleep.

Since osteoarthritis often includes inflammation in the joint, it’s important to eat foods that help reduce inflammation and provide joint-supporting nutrients. These include fatty fish, leafy greens, berries, dried figs, walnuts and cruciferous vegetables (like broccoli, Brussels sprouts and kale). There is evidence that drinking tart cherry juice may ease joint pain and inflammation in people with osteoarthritis and gout (a form of arthritis that involves painful needle-like crystals that form in the joint). 

Vitamin C is an essential nutrient for collagen production. And collagen is necessary for healthy connective tissue, like cartilage, tendons and ligaments in and around joints. So include plenty of citrus and tropical fruits, kiwi, strawberries, tomatoes, cruciferous veggies, bell peppers and potatoes in your day. 

Protein is also necessary for healthy joints, as it provides the building blocks for connective tissue repair and maintaining strong muscles and tendons surrounding the joint. Some tasty anti-inflammatory proteins include beans, fatty fish, lentils and nuts. 

It’s also important to stay well-hydrated. Joints contain synovial fluid, which lubricates the joints, allowing them to move smoothly. Since synovial fluid is, well, fluid, you need to be well-hydrated to have enough of it. Your pee can be a good indicator of your hydration status. Shoot for a light straw- or lemonade-color. 

We’ve got several anti-inflammatory meal plans to choose from if you’re ready to dive in. If you’re just getting started, we recommend our 30-Day Anti-Inflammatory Meal Plan for Beginners. If you’re a little further along in your wellness journey, give our 30-Day High-Protein, High-Fiber Anti-Inflammatory Meal Plan a go.  

Our Expert Take

A new systematic review and meta-analysis found that aerobic exercise seems to have the most overall benefits for knee osteoarthritis, though other forms of exercise also showed specific benefits. Use these results as a guideline, and remember that the best physical activities for you if you have osteoarthritis are ones that you enjoy, will stick to and don’t exacerbate your symptoms. It’s also important that you support your joints with anti-inflammatory foods, hydration, plenty of rest and lowering your stress levels.