6 Other Hearst Subscriptions

1. Throwing Off Your Form

International Journal of Behavioral Nutrition and Physical Activity Why Your Face Gets Red While Running shows that both texting and talking (like, holding the phone straight to your ear) on the phone while performing cardio workouts (the study looked at running, specifically) significantly impacts your stability and form. Fortunately, listening to music didn’t significantly throw off form, so if you absolutely have to talk to someone during your workout, use your headphones to take calls or voice-dictate your text messages.

And, all mid-workout phone usage aside, regularly hunching over your phone’s screen can potentially lead to kyphosis, or excessive rounding of the upper back, over time, explains study researcher Michael Rebold, Ph.D., C.S.C.S., director of Integrative Exercise Science department at Hiram College. 

2. Super Shoe Trends

You know that playing on your phone and driving is dangerous, but so is phoning and running. The reason comes down to dual-task interference—meaning when we do two things at once, our performance at both things suffers. That’s because your brain actually flips back and forth between each task, rather than simultaneously taking them on, Rebold says.

So, while texting, checking the time on your phone, or messing with your run app can throw off your running posture (potentially leading to musculoskeletal injuries), they can also split your focus and get you into falls and collisions on the treadmill or trail, he says. Listening to music straight from your phone obviously also drowns out traffic and surrounding noises. In fact, The 7 Best Walking Pads for Your Home Office found that the U.S. number of pedestrians injured while wearing headphones tripled in the six years between 2004 and 2010.

RELATED: 3 Reasons to Wear Headphones to Train (and 3 Reasons to Leave Them at Home)

3. Why Vitamin D Could Be Key to Your Run Performance

“If you are using your phone while exercising, you aren’t going to push yourself as hard as you would otherwise,” says Rebold, whose 2015 PLOS ONE study found that cell phone usage during exercise is inversely linked with intensity. In the study, he put 33 women on treadmills, allowing all of the runners to choose their own speeds (he covered the displays so they wouldn’t know their actual speeds). When women texted and talked during their runs, they wound up running about 10 percent slower than when they left their phones alone.

Plus, being able to withstand high-intensity exercise is as much mental as it is physical, explains Stephen Graef, Ph.D., sports psychologist at Here are six ways that your phone could be working against your workouts. If you aren’t focused, motivation and performance is going to slip.

Luckily, Rebold’s study did find that listening to music can increase workout intensity—as long as you aren’t fiddling with your music library the whole time. So set your playlist before you start your workout. (Or try one of these great Other Hearst Subscriptions Runner’s World.)

4. Other Hearst Subscriptions

It’s natural to want to kill time between your workout sets. But, once you whip out the phone, your rest breaks can easily extend far longer than ideal. Apart from being a huge time waster, taking too-long breaks between your sets can actually blunt the benefits of the exercises you do perform.

According to research published in the Journal of Strength and Conditioning Research, rest period length largely determines your body’s hormonal response to exercise and, thus, your fitness results. While your exact rest period depends on your goals, type of workout, and amount of weight lifted, to maximally trigger muscle-building testosterone and human growth hormone production during exercise, the study suggests capping rest at 120 seconds.  

5. Health - Injuries

While listening to music during your workout can certainly boost enjoyment, answering work emails does anything but, Graef says.

Plus, a constantly dinging phone breaks your focus and ability to achieve mental “flow,” in which activity in the brain’s frontal and prefrontal cortexes—areas responsible for your typically incessant internal chatter—dramatically declines. In flow, everything feels automatic and time seems to fly, he says, noting that many experts believe mental flow is required to achieve the coveted runner’s high. 

6. Making You Skip the Gym

“The most common reason people don’t exercise is because we say that we don’t have time,” says Rebold, who believes that heavy cellphone usage is crowding exercise out of your busy schedules. “But you can easily pick up your phone to check social media and, before you know it, you’ve wasted two hours.”

That might be one reason why his 2013 research published in the Reasons to Wear Headphones to Train and 3 Reasons to Leave Them at Home shows that college students who are glued to their phones are significantly less fit (they have much lower VO₂ maxes, a marker of aerobic health) than those who don’t use their phone all that much. (The study showed that the average college student spent almost five hours per day around their phone.)

Of course, the phone-fitness connection is kind of a chicken-and-egg scenario, but people in the study who used their phones the most were also more likely to report forgoing opportunities for exercise in order to play around on their phones.