Planning on ramping up your exercise regimen? There may not be a free app for that - at least not a reliable one.
Researchers from the University of Florida found that only one of 30 popular free fitness apps for iPhones meets the majority of guidelines for physical activity from the American College of Sports Medicine, the world's largest sports medicine and exercise science organisation.
When compared to the guidelines for aerobic exercise, strength or resistance, and flexibility, the top-scoring app was the Sworkit Lite Personal Workout Trainer App with 9.01 out of a possible 14 points, researchers said.
Each app was scored across those three categories, examining to what extent they adhered to the specific American College of Sports Medicine guidelines, including parameters for safety, warm-ups, cool-downs, stretching, intensity, frequency and progression.
While more than half the apps included some of the recommendations for aerobic exercise and 90 per cent met at least one criterion for strength and resistance, two-thirds of the apps did not meet any of the flexibility criteria.
"While apps have great potential to give more people access to workouts that could help them achieve a healthy weight and fitness level, we found that the vast majority of apps are not as safe as they could be and do not give users the type of well-rounded workouts known to be most effective," said Francois Modave, associate professor in the UF department of health outcomes and policy and lead author of the study.
Ultimately, only Sworkit Lite Personal Workout Trainer met more than half of the criteria. Three apps met more than half the criteria in the aerobic category. Four apps earned half the possible points in the strength or resistance category.
No app scored above 50 per cent in the flexibility category.
"Several of the apps contained high-quality content in one of the three categories, but almost none of them had high-quality content in all of them, especially flexibility," said Heather Vincent, assistant professor in the department of orthopaedics and rehabilitation in the UF College of Medicine.
"This is a problem because flexibility is important for good exercise form, relaxation and cool-down," Vincent said.
In addition to not meeting the specific criterion for each category, 23 out of 30 apps did not provide an actual training plan, explain how to choose a workout or explain how to organise the workouts through the week.
That makes it difficult, especially for beginners, to follow a safe and physiologically sound progression in their exercise regimen, researchers said.
"The issues with these apps place users at risk for injury because the apps fail to prepare them to take on the exercises, use proper techniques and address safety issues surrounding different types of exercise," said Modave.
The findings were published in the Journal of Medical Internet Research.