THURSDAY, July 18, 2013 (HealthDay News) -- Smartphone users just might be the new couch potatoes.
Researchers studying college students found that cellphone use -- much like watching television -- may significantly decrease physical activity and fitness levels.
"Using a cellphone doesn't have the same kind of negative stigma that sitting on the couch and watching TV has, but it can be just as bad for you," said study co-author Jacob Barkley, an associate professor of exercise science at Kent State University in Ohio.
The study found that students spend an average of almost five hours on their cellphones and send hundreds of text messages every day, Barkley said.
Cellphones -- also called smartphones -- have become multifunction devices with capabilities similar to an Internet-connected computer. Virtually anywhere and always, users can not only make calls and send texts and emails, but they can interact with Twitter, search the Internet, watch videos and live events, and play video and other games.
All these activities are essentially sedentary, the researchers noted.
Despite the fact that cellphones are mobile devices, they slow people down, Barkley said. Texting on the way to the bus stop, people walk more slowly, trying to do two things at once. Going to the park for a run, they stop to look for messages, check movie times and make a date. Walking past a beautiful scene, they halt and take a photo, and then send it to their friends via Facebook.
"Before you know it you've fallen down into this little wormhole sitting on a park bench, playing on your phone," Barkley said.
Smartphones have enormous capacity to significantly change people's lifestyles and health habits, a public health expert agreed.
"We have to look at this similar to what happened in the industrial revolution and how it changed us," said Nancy Copperman, director of public health initiatives at North Shore-LIJ Health System, in Great Neck, N.Y. "A study like this raises the importance of how this technology affects how we move, eat and sleep. We have to look at the impact of technology on our health."
Copperman said heavy cellphone use can create mindless eating, much as television does. If you're using your cellphone during much of your time awake, you have to sometimes be eating while using the device, she said.
Cellphone use can also affect sleep, study co-author Barkley noted. He said some students have been known to "sleep text" -- sending messages while they're sleeping and not remembering they did it when they wake up.
Copperman said she worries that while this study focused on college students who were about 20 years of age, many of today's elementary school students are just as tethered to smartphones. "This is probably affecting physical activity in younger kids now, too," she said.
For the study, the researchers surveyed more than 300 college students about their cellphone use, leisure activities and physical activity. Then 49 students used a treadmill test to evaluate their heart and lung fitness.
In that group, those who spent a lot of time on their cellphones -- up to 14 hours daily --- were less fit than participants who only averaged about 1.5 hours of use.
The findings took into account factors such as gender, percentage of body fat and "self-efficacy" -- the participant's confidence that he or she could be active in a variety of settings, Barkley said.
High-frequency cellphone users tended to report they were involved in more sedentary activities than were low-frequency users. The researchers said that high cellphone users may also be attracted to other forms of digital media such as television, movies, computers and video games.
However, the research can't conclude that cellphones are causing people to be less fit, Barkley acknowledged. "It's possible that less fit people use their cellphones more," he said.
Copperman offered some practical advice. She thinks parents should monitor not just what their children are doing on their smartphones, but how frequently they are using them. Adults should start monitoring themselves, too, she suggested, noting if they're interrupting physical activity by using their phones, or making their cellphone their dinner companion.
"People should take time from their cellular technology for a better quality of life," Copperman said.
The study appeared online recently in the International Journal of Behavioral Nutrition and Physical Activity.
Learn strategies to increase physical activity from the U.S. Centers for Disease Control and Prevention.