The Surprising Way Exercise helps Knee Arthritis
Exercise is safe — and will actually help your knees
Nothing ruins good sound science more than a Ph.D. in google searching
Knee arthritis is very common in orthopedic practice.
A common misconception is that exericse harms the knee.
“My sisters, husbands, second cousin once told me I cannot exercise as I have arthritis in my knees.” [Also known as a bad google search]
The reality — exercise is important for decreasing symptoms of arthritis.
Let's talk about knee arthritis and exercise.
Arthritis is one of the most common orthopedic complaints. There are various types of arthritis, but the most common we encounter is Osteoarthritis — age-related loss of cartilage around joints causing pain and inflammation.
There is no cure for osteoarthritis (despite what some affiliate marketers will tell you).
As surgeons, we are taught to maximize all the nonsurgical treatments prior to undertaking surgery, such as knee replacement surgery. I concede some surgeons don’t read the textbook.
The two most effective non-surgical treatments for knee arthritis are
1. Exercise
2. Weight loss
Topic of this article:
Is it safe to exercise when you have knee arthritis?
Short Answer = YES
Only caveat being, it that you may have to modify the type of exercise you do.
Is this supported by science?
Short Answer = YES
Is there any evidence of the harmful effects of exercise on knees with arthritis?
The short answer to this is no.
Arthritis is caused by age-related changes to cartilage, but the concern is that impact exercise may accelerate these changes.
A trial in 2019, published in the British Journal of Sports Medicine grouped a collection of interventional trials which looked at the effect of exercise of MRI assessed cartilage damage. They concluded no difference across the multiple trials, however, did concede the evidence was low quality.
Running has always been the enemy of knees.
Even running appears to have a limited effect on the cartilage in knees, and may actually be adaptive and change with repeated running.
Next question — how about benefit?
This is where data is much more convincing.
Almost all trials looking at exercise in the setting of arthritis of the knee show benefit.
A Cochrane review in 2015 concluded with moderate evidence (pretty good for Cochrane reviews) that exercise significantly causes improvement in pain and physical function. They concluded the improvement is comparable to taking daily anti-inflammatory medications.
The Cochrane library is an academic body who review health related outcomes in the form of reviews. It is generally accepted as a reputable source of data.
Why does exercise help?
This is less poorly understood.
There are multiple theories, and in reality, all of these are probably important.
Exercise builds muscle mass
Thigh muscles act as a external splint for the knee
The thigh muscles are particularly important in the knee, hence the role of cycling. A study using weight training, showed that those with increased thigh muscle size had the best pain relief in knee arthritis.
Exercise decreases inflammatory proteins
This occurs in the whole body, but also locally in the knee.
This is very complex, but it appears that regular movement (as in cycling, walking, gentle running) causes improved fluid dynamics in the knees — washing out damaging inflammatory proteins in the knee. Studies have shown lower levels of pro-inflammatory proteins in the blood, but also the knee in those who participate in aerobic exercise.
Exercise improves balance and walking
Instability is a common symptom with arthritis.
Exercise programs such as Tai Chi, and pilates have been shown to improve patient outcomes in knee arthritis.
Exercise helps with weight reduction
Weight control is one of the most important protective mechanisms for knee arthritis.
A modest weight loss of 5% of body weight — can lead to improvement in knee function scores by almost 20%, a study has found.
Note — 8x bodyweight is transferred through the front of the knee when climbing stairs — so 5kg of weight loss = 40 kg less weight on knees when going up/down steps.
What about the ideal type of exercise?
There are a number of studies that have looked at multiple different types of exercise.
Some notable exercise and knee arthritis studies:
- Tai Chi and improved balance and functional scores
- Strength training improves function and pain
- Cycling improves pain and daily function
- Aquatic exercise improves function
- Aquatic cycling improves function and pain
The conclusion: Most trials show moderate benefit, with no evidence of harm from exercise.
My advice…
There is no evidence exercise is harmful for arthritis
Exercise is important
Find an activity that you enjoy and make it part of your daily routine
Use the experts if you can — physiotherapists, exercise physiologist, well trained personal trainers.
Dr. Maher is a practicing orthopedic surgeon. He also runs a successful online non-operative program for knee, shoulder, foot problems. Please feel free to message or email aT orthopodology at gmail dot com for more information. Happy reading. Please Follow, Clap Etc.
