Downloading a free fitness app may seem like a smart way to get moving, but a new study reveals most fail to measure up to physical activity guidelines from the American College of Sports Medicine (ACSM).

University of Florida researchers scored apps based on aerobic activity, strength and resistance, and flexibility. Of the 30 popular free workout apps available for iPhone and Android that were tested, just one received an overall score above a 50%: Sworkit Lite, which offers strength, yoga, pilates, and stretching workouts from 5 to 60 minutes in length.

Here is the researchers' full list, ranked by "overall quality score":

Photo: Courtesy of University of Florida

"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 François Modave, PhD, associate professor in the Department of Health Outcomes and Policy at the University of Florida, told Health.

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The study, which was published in the Journal of Medical Internet Research, also discovered that safety guidelines and warnings were absent or fairly weak on most of the apps, which can make beginner exercisers more prone to injury.

Another problem the researchers came across were app paywalls. While some might have matched more of the ACSM’s fitness criteria when all of the resources were paid for and unlocked, apps were still deemed unsafe if the free access was lacking. "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.

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So, should you steer clear of free fitness apps? Not necessarily, but you should vary your sources of exercise information.

For example, if you really like using workout apps, you can use multiple programs so you get a complete fitness regimen, adds the study's co-author Heather Vincent, PhD, a member of the ACSM Consumer Information Committee.

“My piece of advice would be try to find an app that contains a bit of everything to get started," Vincent says. "But if you’re having trouble finding the perfect, user-friendly option, choose a couple that might be really close and that are very strong on one or two components. You should try doing those components from one app and maybe choose a different one to complete the program.”

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