By Robert Preidt
For the study, researchers analyzed data gathered from more than 900 pairs of identical and same-sex fraternal twins in Washington state during the early stages of the pandemic.
While 42% said their physical activity levels fell, 27% said they rose. Another 31% reported no change.
Those who said their physical activity levels had declined in the first two weeks after stay-at-home orders were issued reported higher levels of stress and anxiety, a finding that the researchers expected.
But they were surprised that the same was true among many twins who boosted their physical activity levels, according to the study.
"Certainly, people who don't exercise know that there are associations with mental health outcomes, yet the ones that increased their exercise also reported increased anxiety and stress," said study co-author Glen Duncan. He's a professor at Washington State University College of Medicine, in Spokane.
"It's hard to know exactly what's going on, but it could be that they are trying to use exercise as a means to counter that stress and anxiety they're feeling because of COVID," Duncan added in a university news release.
The link between decreased physical activity and stress was confounded by genetic and environmental factors, the researchers noted.
In twin pairs where one reported decreased activity and the other remained the same, there was no difference in their stress levels, the findings showed.
"It's not necessarily that exercise won't help you personally manage stress," Duncan said. "It's just that there is something genetically and environmentally linking the two."
The researchers plan to continue following the twins.
"At least in the short term, it seems there is not a lot of impact from either decreasing or increasing physical activity in terms of handling stress and anxiety, but that might be different after two or three months under COVID restrictions," Duncan said.
The findings were published online recently in the journal PLOS One.