Though we understand exercise to be good for our wellbeing, there is a lot still to learn about the complex and varied ways physical activity drives positive health outcomes in humans.
Scientists digging into the molecular details of this relationship have made a significant discovery, pinpointing a modified amino acid that spikes in the blood following intense exercise, and travels to the brain to suppress hunger and in turn drive weight loss.
“We’re all generally aware that exercise is beneficial,” said Jonathan Long, an assistant professor of pathology at Stanford University, who led the research. “It’s good for body weight and glucose control. But we wanted to take a look at that concept in more detail – we wanted to see if we could dissect exercise in terms of molecules and pathways.”
To this end, Long and fellow study authors from University of California, Davis and Baylor College of Medicine turned to a technique called metabolomics. This meant leveraging mass spectrometry to track the concentration of different molecules in tissue and blood samples, and how exercise caused levels of certain ones to rise and fall.
Initially, this was put to use on mice who were made to carry out a short session on a treadmill, with the scientists able to pinpoint a large spike in a certain molecule after the workout. Analysis of blood from racehorses came next, with the team again seeing a spike in the same mysterious molecule after their exercise.
Alice Herb, 88, an intrepid New Yorker, is used to walking miles around Manhattan.
But after this year of being shut inside, trying to avoid covid-19, she has noticed a big difference in how she feels. “Physically, I’m out of shape,” she told me. “The other day, I took the subway for the first time, and I was out of breath climbing two flights of stairs to the street. That’s just not me.”
Emotionally, Herb, a retired lawyer and journalist, is hesitant about resuming activities even though she’s fully vaccinated. “You wonder: What if something happens?” she said. “Maybe I shouldn’t be doing that. Maybe that’s dangerous.”
Millions of older Americans are similarly struggling with physical, emotional and cognitive challenges following a year of being cooped up inside, stopping usual activities and seeing few, if any, people. If they don’t address issues that have arisen during the pandemic — muscle weakness, poor nutrition, disrupted sleep, anxiety, social isolation and more — these older adults face the prospect of poorer health and increased frailty, experts warn.
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