Many iPhone fitness apps ignore comprehensive workout guidelines, study finds

Researchers at the University of Florida tested 30 popular free apps, scrutinizing them for their handling of three essential aspects of fitness: aerobic exercise, strength/resistance, and flexibility, the Washington Post said. Although 90 percent of apps met some of the strength/resistance guidelines, only a little over a half met some aerobic criteria. Two-thirds of apps didn't meet any flexibility standards.

Just a single app, Sworkit Lite, met over half of ACSM criteria, scoring 9.01 out of 14.

The lead author on the study, Francois Modave, warned that people risk being injured with many apps because they don't prepare people for proper form or safety.

Other apps in the top five included 7 Minute Workout, StrongLifts 5x5, Running for Weight Loss, and JEFIT Workout, but none of them scored over 5.39. Four apps tied for last place at 0.33 — three of them concentrated on ab workouts.

The ACSM told the Post that while it doesn't expect every app to include all three pillars, ones that don't need to be combined with supporting workouts to fill in the gaps.

iPhone-compatible fitness apps and wearables have become increasingly popular in recent years. Apple itself recently entered the market with the Apple Watch, which can monitor things like steps, distance, and heart rate, and sync it with iOS apps. Like most fitness trackers, it lacks a way of directly monitoring strength training and concentrates on running and walking instead.