This statement quite often leaves people somewhat confused especially after they’ve been told the impact chronic low-grade inflammation has on insulin resistance, which is a precursor to developing diabetes.
However, while an exercise bout does increase levels of pro- inflammatory messengers called cytokines it only tells part of the story. The above statement also challenges the concept that all inflammation is bad for us. This is certainly not the case. The fact that we are able to fight off viruses and infections is testament to the benefits of an acute inflammatory response mediated by our white blood cells.
You may have noticed that I’ve talked about acute inflammation (which implies a short term, high magnitude response) and chronic low-grade inflammation. It is the latter that we are finding is highly associated with chronic diseases of today which includes cardiovascular disease, arthritis, depression and diabetes.
However exercise appears to have an acute inflammatory response which in turn increases the production of free radicals which then switches on our body’s production of antioxidants that are ultimately responsible for the protective effect on our heart.
Further to this, the inflammatory response to exercise is mainly driven by a cytokine (or technically a myokine since it is produced in the muscle) called interleukin-6 (IL-6) which has been shown to suppress the effects of another pro-inflammatory cytokine called TNF-alpha. This cytokine is produced by sick adipose cells (storage cells for fat) and induces insulin resistance. Exercise also increases the levels of anti-inflammatory cytokines (IL-1ra and IL-10) so while exercise might acutely create a pro-inflammatory response, the net effect after the bout of exercise is actually anti-inflammatory in nature.
So what are the take home messages here? Firstly a little bit of inflammation through exercise is good for you. A little bit of short-term stress only makes our systems stronger. Our body is an amazing machine that can adapt and respond to these challenges and it has many mechanisms to respond to these natural stresses.
Finally we need to understand that when our body is already under inflammation either acutely through sickness or chronically through diseases such as type II diabetes and arthritis, we need to choose intelligent exercise. By that I mean that the movement itself through poor biomechanics, or through an inappropriate intensity, should not introduce too much inflammation into the system. It is in these situations where we can experience adverse effects including excessive joint pain and musculoskeletal injuries.