Exercise has its benefits in reducing anxiety and stress, however, it may not be enough for the levels caused by the novel coronavirus, according to a new study.

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In a study of twins led by Washington State University researchers, people who reported increasing their physical activity after the start of COVID-19 stay-at-home orders reported higher levels of stress and anxiety than those whose activity levels stayed the same.

In the study, published recently in the journal PLOS ONE, researchers analyzed data from over 900 pairs of identical and same-sex fraternal twins from the Washington State Twin Registry. Those who reported a decrease in physical activity within two-weeks after the start of stay-at-home orders had a perceived higher level of stress and anxiety, which was expected. But surprisingly, many of the respondents who increased their physical activity felt the same way.

"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 lead author Glen Duncan, a professor in WSU's Elson S. Floyd College of Medicine. "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."

The twin survey was conducted from March 26 to April 5, 2020, in the early days of the pandemic. Washington State and many other states issued their first stay at home orders near the end of March in an attempt to curb the spread of COVID-19. Participants were asked about changes in their physical activity compared to one month previously. Of the survey respondents, 42 percent reported decreasing levels of physical activity since the COVID crisis began, and 27 percent said they had increased their activities. Another 31 percent reported no change.