What Really Wears Out Your Joints

Picture by Dr Howard Luks

I remember treating many cases of older patients who had total hip or knee replacements due to osteoarthritis (OA) when I was a much younger physiotherapist. 

Upon asking these patients, they always wondered why they had worn out their joints despite not exercising. Some were very sedentary, while others had no time to exercise since they were more concerned with making enough to feed their families.

I've written previously that running will not wear out your knees (or your joints). So what does? There is now evidence that OA is not due to a mechanical wear and tear process. Even if you already have OA, exercise will not wear out your joints quicker. 

Of course there are mechanical causes of OA. People who are severely bow legged or have severely knocked knees can be more prone to developing OA since one side of the knee joint is over loaded. Certain fractures near a joint can lead to post traumatic OA (due to mal- alignment). 

Patients whose meniscus is torn and subsequently removed have an increased risk of developing OA. Which is why surgeons now rarely remove the whole meniscus, just the torn bit.

So, what causes arthritis in our joints? For those without any previous injuries to the joint, we have hundreds of proteins, cytokines, chemicals and other compounds that forms the articular cartilage, which lines our joints. When the joints are in good health, these chemicals support articular cartilage health and nutrition.

We do not know exactly why, whether it is due to injury, our diet, metabolism or weight that, OA develops. It may be all of the above when a 'switch' flips. Changes in the joint(s) similar to changes associated with other chronic diseases happens. That switch causes an increase the production of chemicals that harms our articular cartilage (Wang et al, 2015).

Over time, these chemicals cause injury to the articular cartilage cells. This weakens the articular cartilage and its ability to withstand load and stress.

The articular cartilage can become thinner when not functioning well. This can lead to inflammation, swelling, warmth and pain. This chronic low grade inflammation is what appears to cause OA. This is the same chronic inflammation thought to cause other chronic diseases like heart disease, fatty liver and Type II diabetes.

Researchers are still trying to understand how all these proteins and substances affect articular cartilage health and the incidences of OA. 

Exercise has actually been proven to decrease the concentration of these proteins and substances that harm our articular cartilage.

Helmark et al (2010) showed that IL-10, a chemical that protects articular cartilage in the knee was produced in response to exercise. Similarly, COMP (a protein that is a marker of cartilage degeneration) was decreased in the knee with exercise.

Another research paper by Hyldahl et al (2016) demonstrated that running was associated with a decrease in cytokines (chemicals) in the knee related to articular cartilage wear and tear. 

Studies are suggesting that metabolic health definitely plays a bigger role in causing OA. Yes, other than Type II diabetes, dementia, high blood pressure and heart disease, metabolic issues are also thought to be involved in the development of OA. All tissues in our body, including our articular cartilage are sensitive to our dietary intake. The earlier we realize this, the better off we will be.

Too many health care professionals ask their patients to stop running (or exercise) to 'save' their joints. In actual fact, running and other knee exercises have been shown to relieve mild knee arthritis and does not harm articular cartilage.

Exercise has been unequivocally proven to be the most effective treatment for early and moderate OA in our joints. You do not have to stop exercising. 

Let your symptoms be your guide. If there is no swelling and no pain, you can still run or exercise. Be careful with the distance, intensity and frequency of exercise. You may also want to cycle or swim occasionally. Or try a different shoe, or different running surface and/ or include a weight training session to get yourself stronger. 

References

Helmark IC, Mikkelsen UR, Borglum J et al (2010). Exercise Increases Interleukin-10 Levels Both Intraarticularly And Peri-synovially In patients With Knee Osteoarthritis: A Randomized Controlled Trial. Arthritis Res Ther. 12, R126. DOI: 10.1186/ar3064

Hyldahl RD, Evans A, Kwon S et al (2016). Running Decreases Knee Intra-articular Cytokine And Cartilage Oligomeric Matrix Concentrations: A Pilot Study. Eur J Appl Physiol. 116 2305-2314. DOI: 10.1007/s00421-016-3474-z

Wang X, Hunter J and Xu CD (2015). Metabolic Triggered Inflammation In Osteoarthritis. OA and Cartilage. 23(1): 22-30. DOI: 10.1016/j.joca.2014.10.002

High Intensity Interval Training (HIIT) Reduces Cancer Cell Growth?

Picture by richseow from Flickr

I've written positively before about the effects of running on cancer a few years ago. Now there seems to be more evidence that even a single session of high intensity interval training (HIIT) may significantly slow the growth of colon cancer cells.

Researchers had male colorectal cancer survivors perform either a single HIIT session or do HIIT regularly for a month.

After a ten minute warm up, the single HIIT group did four intervals of four minutes cycling (at 85to 95 percent maximum heart rate) with three minutes of recovery in between. The other group did this same session three times a week for a month.

Picture by jungle jim3 from Flickr

Blood samples were taken from these subjects before and after the HIIT sessions. Blood samples before exercise had no effect whatsoever on the cancer cells. Blood samples after the HIIT sessions showed a decrease in the cancer cells immediately.

While comparing the single session HIIT group with the other, there was no significant difference in the blood samples.

During high intensity exercises, our muscles releases lots of myokines (inflammatory cytokines) compared to moderate intensity exercises.

The researchers attributed the cancer cells reduction to cytokines (or inflammatory markers) found in the bloodstream after exercise.

The researchers suggested that the reduction in cancer cells in the colon is not specific to those who had cancer before. Other studies have found similar reductions in prostate cancer cells in healthy individuals as well.

Every individual tolerates and responds differently to exercises, especially HIIT sessions. Train don't strain is important too.



Reference

Devin JL, Hill MM et al (2019). Acute High Intensity Interval Exercise Reduces Colon Cancer Cell Growth. J Physiol. DOI: 10.1113/JP277648.