Today I am sharing a new paper that’s just come out on mental stress, inflammation, and heart health. These guys got a sample of adult men to do a mental stress task in the afternoon and then measured various cardiovascular outputs, like blood pressure and blood flow in response to the stress. But they got these people to do this twice under two different conditions. The first condition was that they exercised quite intensely 6 hours prior in the morning (a leg exercise, to be specific), and the second condition was that they relaxed for 45 minutes in the morning instead. The idea was that they wanted to exercise in the morning to produce local inflammation which would last until the afternoon (which it did: IL-6, and inflammatory maker, was much higher after exercise).
As you might be able to guess, mental stress increased blood flow, including to the leg that did the exercise, and this increased in both conditions, whether they exercised in the morning or not. But in the exercise condition, the increase in blood flow in the leg after the mental stress was not as great compared to the relaxing condition. So the leg exercise, and the short-term inflammation that came with it, meant that blood flow was not as reactive to mental stress as it should have been. The authors then suggested that this shows that inflammation can be a factor in things like heart attacks, especially since many of them are in response to mental stress, and if blood isn’t flowing properly, this can cause a heart attack.
Here is what I am confused about. Exercise is supposed to be good, and while it increases inflammation short-term, over time it contributes to good health and, actually, reduced inflammation. So even though it is generally agreed that inflammation can lead to cardiovascular dysfunction, I think it’s strange that this study’s methodology was so heavily focused on exercise. Although strenuous exercise would indeed raise levels of local inflammation, the study is only short-term (one day) and neglects to discuss the overall benefits of consistent exercise over time. Perhaps I’m simply interpreting the paper incorrectly or making an issue of something that isn’t that important. For example, I can see that the paper was mainly trying to show that inflammatory markers reduce blood flow after mental stress, and that they were simply using intense exercise to get levels of inflammatory markers to rise. But I think they could have done this is another, more controlled way (perhaps even by injecting the participants with cytokines). I’d appreciate any readers contributing their opinion on this article, to help clarify the reason for this methodology.
In any case, I think this blog is about due for an Exercise Feature Series, hopefully coming up soon.