The articles on activity and exercise you are likely to find on the Web may be inspiring, but they rarely reflect our national guidelines' recommendations. What's worse, according to a new study, they may actually be doing more harm than good, especially for people most likely to turn to them — those who haven't been particularly active lately but would like to start.

“Online exercise advice is incomprehensible for many and incomplete for everybody,” said researcher, Brad Cardinal, a kinesiology professor in Oregon State University's College of Public Health and Human Sciences and co-author of the study. “There wasn't anything we came across that was a complete message, and for many people, they would be left out of it altogether”

Most online sources focus more on abs and buns than on hearts and lungs and are more about improving appearance than improving health.

The team looked at information from 72 different Web articles published or updated between 2008 and 2018. They compared the messages in these articles to those in the Department of Health's 2008 Physical Activity Guidelines. Then they condensed the 76 pages of the 2008 guidelines into 17 sets of do's and don'ts applicable to adults 64 and younger.

The tips included general advice, such as “avoid inactivity — any activity is better than none” and more specific guidance, such as “attain 150 minutes a week of moderate intensity aerobic physical activity.” A brisk walk is one commonly cited and popular type of moderate intensity aerobic activity.

When they then compared the messages in their Web sample of 72 fitness articles to the messages in these do's and don'ts, they did not find a good match. The vast majority of articles did not present a single message that was consistent with any of the 17 guidelines.

Most online sources focus more on abs and buns than on hearts and lungs and are more about improving appearance than improving health, according to Cardinal.

The authors found Web recommendations on aerobic exercise were more likely to be correct than those about muscle strengthening. Few recommendations on muscle strengthening included correct or complete information.

The reason this is so concerning is that it's people who are trying to become more active who are most likely to be misled by the material, explains Cardinal. Instead, most of the articles are designed for people who are already exercising, so if someone who had been leading a largely sedentary life tried to follow the advice, they could end up injured. People should start slowly when they are trying to become more active.

The kind of website — commercial, government, professional association or voluntary health agency — on which the information appeared did matter for certain types of articles, but the study found that generally “web articles often may contain advice that is inconsistent with the established physical activity guidelines, regardless of production source.”

The article's bleak conclusion: “The results of this study substantiate that most educational materials on physical activity are not credible; most of the web articles in our sample disseminated inconsistent and/or inaccurate information…”

Caution is advised. For more information on the 2008 guidelines, revised in 2018, see “New Physical Activity Guidelines.”

The study is published in the Translational Journal of the American College of Sports Medicine.