As we exercise, we increase and decrease the levels of hundreds of molecules in our bloodstream that are related to our metabolic health, even if we only exercise for a few minutes, so a complex and encouraging study the molecular effects of being active.
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The study, in which more than 1,000 men and women participated, adds to the growing evidence that exercise improves our health in large part by changing the number and types of cells in us.
At this point, of course, there is no reasonable debate about whether exercise is good for us. It is.
Countless studies show that people who are active are less likely than sedentary people to suffer or die from a variety of health problems, including heart disease, diabetes, dementia, cancer, and obesity. Active people also tend to live longer and feel happier.
But we still know surprisingly little about how exercise changes us for the better. What are the many interconnected biological steps and transmutations that enable a walk today to extend our lifespan in decades?
This question has recently aroused great interest in research on “omics” – the study of all molecules in our blood or other tissues that are part of a particular biological process. For example, genomics quantifies the many molecules involved in genetic activity. Proteomics does the same for proteins, microbiomics for the content of our microbiomes, and metabolomics for molecules related to metabolic processes. (There may be overlaps between different omics.)
Understanding how movement affects the levels of the various molecules in us is important, as these changes are likely the first step in a complex cascade of other biological actions that contribute to better health. You increase some molecules, decrease others, and you start organ communication, gene expression and other processes that then change the way we make and use insulin, burn or store fat, respond to cholesterol, and so on.
A number of important recent studies have looked at the omics of exercise, including a fascinating experiment showing that brief exercise quickly changes the levels of 9,815 molecules in the bloodstream. But this study, like most other exercise and omics studies, involved relatively few volunteers – 36 in this case – and did not associate molecular changes with subsequent health outcomes.
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For the new study, published in the journal Circulation, researchers at Massachusetts General Hospital in Boston and other institutions decided to increase the number of practitioners whose omics should be analyzed and also to try to find links between the omics data and to find later health.
Conveniently, they had access to a large group of potential volunteers among men and women who had previously participated in the long-term Framingham Heart Study, which is monitored primarily by researchers from Boston University. The scientists asked 411 middle-aged volunteers who participated in the study to visit the lab and exercise by cycling to exhaustion on a stationary bike. Most of the driver’s efforts took a little under 12 minutes. The researchers took blood samples before the ride and afterwards within about a minute of the cyclist leaving.
The scientists then ran the blood samples through a mass spectrometer, a machine that counts and quantifies molecules. The researchers focused on metabolites, which are molecules related to metabolic processes. The term “metabolite” is a bit arbitrary, but for this study, researchers focused primarily on molecules that can affect insulin, fat burning, cholesterol, blood sugar, and other aspects of cellular fueling.
They found a lot.
Of 588 metabolites examined, values increased or decreased by more than 80 percent during the short journeys in general. To reinforce these results, the scientists repeated the experiment with another 783 Framingham volunteers, checking their blood before and after exercise for changes in about 200 of the molecules that were most altered in the first group. These metabolites also changed in the same way as before.
Finally, and perhaps most fascinatingly, the researchers created so-called molecular “signatures” of the levels of some representative metabolites that changed with exercise. They then looked for the same metabolite patterns in stored blood samples that had been drawn decades earlier from previous Framingham participants, while also checking if and when any of those volunteers had died.
The researchers found that the relevant signatures appeared in some blood samples, which tended to come from people who did not die prematurely, suggesting that the type of metabolite changes that occur during exercise will affect health well into the future could improve.
However, this idea is “speculative,” said Dr. Gregory Lewis, director of the heart failure program and director of the cardiopulmonary exercise laboratory at Massachusetts General Hospital, who oversaw the new study. The decades-old blood samples were taken during standard medical tests, not post-exercise, so some people with desirable metabolite signatures may have been born this way and not require training to remodel their metabolites.
Even among the current volunteers, different people’s molecules reacted slightly differently to their exercises.
Overall, obese people developed fewer changes than leaner drivers, suggesting that they might somehow resist some of the benefits of exercise. Men and women as groups also showed slightly mismatched molecular signatures, but age had no effect on people’s molecular responses.
Larger future omics studies should help scientists figure out how and why we all respond to exercise, Lewis said, and allow researchers to define more precise molecular signatures that, on a blood test, could indicate how fit someone is or how body can perform different types of exercises respond.
For the time being, however, the current study highlights how widespread and immediate the effects of exercise can be. “It was barely 10 minutes of practice,” said Lewis, “but it has changed so much” in people. – New York Times
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