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

Blood Poisoning In Extreme Endurance Events

Picture by orangefan_2011 from Flickr

If you haven't trained hard enough for your upcoming marathon or ultra marathon race, beware for there may be more adverse effects than you think.

Extended exercises beyond four hours can put your body at risk if you are not sufficiently prepared. Stomach bacteria may seep into your bloodstream and cause poisoning.

Two different studies looked at runners taking part in two different ultra distance races in Scotland (between 78-130 miles) and Spain (5-day 143 miles stage race).

Before and after the races, blood samples were taken from the runners and a control group not racing.

Blood markers in most of the runners after the races showed traces of blood poisoning. This was similar to what you see if you were admitted to the hospital for food poisoning. Almost all the runners had stomach issues during the race as well. None were hospitalized though.

Some runners even had blood markers resembling those who have sepsis - a potentially life threatening illness where chemicals released into the bloodstream to fight infection actually generate heavy inflammation.

This happens when blood moves away from the stomach area to the working muscles when we exercise. This causes the stomach wall to spread apart and leave open gaps. Endotoxins (naturally occurring bacteria in the stomach) fit through these gaps and leach into the blood. This activates an inflammatory response in the body.

Usually the body can easily clean up this sort of bacteria leaching. Only under heavy duress the body can be overwhelmed. This can occur in extreme exercise conditions, heat stress, illness and infection.

When the weather is hot, blood flow away from the stomach to the working muscles will be more extreme, so strategies to keep the body cool during training and racing is critical.

The researchers added that repeated bouts of inflammation like this can cause long term fatigue, stomach problems and immune disturbances.

What was interesting was that in both studies, runners who trained sufficiently had higher levels of Interleukin-10, a small anti inflammatory protein that helps offsets negative health effects.

Now you know, make sure you train enough for your race.

References

Gill SK, Hankey J, Wright A et al (2015). The Impact Of A 24-h Ultra-marathon On Circulatory Endotoxin And Cytokine Profile. Int J Sports Med. 36(8): 688-695. DOI: 10.1055/s-0034-1398535.

Gill SK, Texeira A, Rama L et al (2015). Circulatory Endotoxin Concentration And Cytokine Profile In Response to Exertional-heat Stress During A Multi-stage Untra-marathon Competition. Exerc Immunol Rev. 21:114-128.