Of the 30 popular free workout apps available for iPhone and Android tested by University of Florida researchers, just one got a favourable review, Health.com reported.
The researchers scored the apps based on aerobic activity, strength, resistance, and flexibility.
"We found that most apps are not as safe as they could be and are not providing users with the most effective workouts," lead author Francois Modave said.
The study also found that safety guidelines and warnings were absent or poorly represented on most of the apps, which can make beginner exercisers more prone to injury.
Another problem the researchers came across were app paywalls.
"If you charge, you at least have to make sure that on the free portion of the app the content is still evidence-based and built on true, expert information," Modave says.
So, should one stop accessing free fitness apps? Not necessarily, said the researchers.
"My piece of advice would be try to find an app that contains a bit of everything to get started," study co-author Heather Vincent, a member of the ACSM Consumer Information Committee, was quoted as saying.
The study was published in the Journal of Medical Internet Research.
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