gaukler wrote:
The studies cited in this video suggest that training actually improves the immune response: https://www.youtube.com/...u7iQmYTWOPxbHj5qQ7nY
definition of training is wide enough that one can drive a figurative 18-wheeler through it
We are specifically referring to prolonged training at intensity at and or above threshold. No one is saying to stop exercising, the question is to whether to completely stop high intensity aerobic exercises.
As for the sources he cited
The first screenshot at 1:33 refers to the following article. Yes, the article mentions "vigorous exercise", but it defines "vigorous exercise" as “exercise that is intense enough to cause large increases in heart rate, breathing, sweating, at a level that makes it somewhat difficult to carry on a normal conversation.” These terms are defined way too imprecisely, as mid-zone 3 would easily qualify as such. As the study does not look into effect specifically of zone 4 and 5, it's rather irrelevant wrt whether high intensity exercise makes one more liable to contract respiratory disease.
The next screenshot at 2:03 refers to this article. Its abstract, which is the only portion of the article discussed in the video, is concerned solely with moderate levels of exercise. Completely irrelevant.
The next screenshot at 2:12 is concerned with response in active vs. sedentary mice. Assuming mice models could indeed be applied to humans, and that a bacterial GI tract disease has applicability to viral respiratory disease, it still doesn't differentiate between highly intense exercise vs merely active.
By this point, I decided to stop watching and click through the links he posted. The first one, titled Debunking the Myth of Exercise-Induced Immune Suppression: Redefining the Impact of Exercise on Immunological Health Across the Lifespans is the only one of the two relevant articles. I personally found the following to be a rather belabored justification for the point the authors are trying to make (selection bias).
Quote:
Contrary to the aforementioned reports that exercise heightens infection incidence, it is often overlooked that other studies indicate that exercise participation may in fact reduce the incidence of infections. For example, a recent prospective cohort study of 1,509 Swedish men and women aged 20–60 years found that higher physical activity levels were associated with a lower incidence of self-reported URTIs (35). A much smaller but very detailed analysis of illness records kept by 11 elite endurance athletes over a period of 3–16 years showed that the total number of training hours per year was inversely correlated with sickness days reported (36). Similarly, another study of swimmers monitored for 4 years found that national level athletes had higher incidence of infections than more elite international level athletes (37). Finally, studies of ultramarathon runners, who undertake the largest volume of exercise among athletes, have shown that these individuals report fewer days missed from school or work due to illness compared to the general population. For example, the mean number of sickness days reported over 12 months was 1.5 days in a study of 1,212 ultramarathon runners and 2.8 days in a study of 489 ultramarathon runners (38, 39). These studies compared their findings to data from the United States Department of Health and Human Services report in 2009, showing that the general population report on average 4.4 illness days each year. Thus, a number of studies challenge the “J-shaped curve,” indicating that athletes undertaking the largest training loads, become ill less frequently than athletes competing at, and training at, a lower level.Furthermore, the authors cite to rodent studies in the section "Transient Changes to Blood Lymphocyte Frequency in the Hours Following Exercise". Problem is, the article cited makes no mention of intensity of the exercise (I don't have access to the article cited). It does raise an interesting issue on whether reduction in circulating lymphocytes just means a distribution of these cells elsewhere, but other than that, not a lot to go by.
Countering this article is the following, which concludes:
Quote:
Although elite athletes are not clinically immune deficient, it is possible that the combined effects of small changes in several immune parameters may compromise resistance to common minor illnesses, such as upper respiratory tract infection. However, this may be a small price to pay as the anti-inflammatory effects of exercise mediated through cytokines and/or downregulation of toll-like receptor expression are likely mediators of many of the long-term health benefits of regular exercise.
Given all that we have, I think at best it's a toss-up (from the articles he cited) between whether intense exercise increases risk of catching an upper respiratory virus.
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Jordano wrote:
But if you are properly isolated who cares about those two hours?- there is no acute immune challenge unless you hit the grocery store immediately post workout. If you are in a low risk group you can work hard, be careful to not get rundown (like others said, sleep more, eat well) and there won't be significant chronic effects. You do you but Im not worried about it on an acute level.Define proper isolation (i'm not trying to challenge you or be facetious).
Public health advice is that the virus per se can survive 48-72 hours on various surfaces, more if it were protected by other substances. Assuming we are talking virus particles per se, that would be 48-72 hours of no contact with the outside, for anyone sharing that living space. No fetching of mail, no walk outdoor, etc.
Doable, yes, but it'll need to be carefully crafted.