ReadWriteBody is an ongoing series where ReadWrite covers networked fitness and the quantified self.

I might as well be dead. Flatlined. As far as my phone’s concerned, my heart rate is a big, fat 0. And it may be Apple’s fault.

For a couple of months now, almost every morning, my Pear Sports app tells me in a stern yet crestfallen tone, "I can't read your heart rate. Tighten your strap and check your sensors.” For whatever reason, my heart rate isn't getting transmitted to my iPhone. And without that data, I can’t quantify my workout. Am I tearing up the pavement or just coasting along? I can guess how hard I’m exercising, but I don’t really know.

And so I waste minutes fiddling with my phone, turning my Bluetooth connection on and off, killing and restarting apps, sometimes even rebooting my phone. Sometimes it works, only to drop a few minutes into a run.

This is frustrating beyond just delaying my workout. I’ve written about the potential for Bluetooth-enabled devices and heart-rate monitoring to unlock new ways to monitor our health and make exercise more productive. But it's hard to see how the mass market will see any of those benefits if they have to deal with the hassles I’ve put up with.

The Fitness-App Blues

Some of my problems are self-inflicted. I test multiple running apps at once, most of which attempt to pick up a signal from whatever heart-rate strap or wristband I’m trying out that day. (I now have a half-dozen in my gym bag, and about as many apps in the Exercise folder on my iPhone.)

That complexity makes the problems hard to pin down. Is it the Bluetooth spec that’s flawed? Apple’s implementation of it? A problem with one of the many apps I'm using? Or just one of those problems that can crop up with any kind of wireless data transmission?

I've tried to isolate the problem through trial and error, without much luck. So I started calling the experts—the developers of the fitness apps and hardware I use.

“Glad you're shedding light on this issue,” said Kristian Rauhala, the CEO of Pear Sports. When I reached him Wednesday afternoon, he was sitting next to his customer-support representative, who’s been dealing with similar complaints since mid-November.

Rauhala said, based on his customer's issues and conversations he’s had with others in the industry, it seems to be a problem that started with the release of iOS version 7.0.4. For whatever reason, that version of Apple's mobile software is causing problems for Bluetooth-dependent apps.

For Rauhala, it’s a crucial issue, since his app uses real-time heart-rate data to coach users like me through a workout.

"If we can't do heart-rate training, we're DOA," Rauhala said.

Kind of like I would be, if my heart rate were actually zero.

It’s hard to know if iOS is actually to blame. Apple did not respond to a request for comment on Bluetooth issues with its software, but users have been complaining about problems with the update on its support forums. A Pebble user also reported problems using a heart-rate monitor at the same time as his smartwatch. It also fits the timetable of problems I've seen with the devices I’ve tested.

Big Sacks Of Water In The Way

Software may not be the only issue. Radio-frequency technologies always deal with obstacles, and the human body is a big one. As far as our wireless devices are concerned, we're just big sacks of water—and radio waves do not transmit easily through water.

Am I expecting too much of my fitness trackers? Am I expecting too much of my fitness trackers?

Mateo Ortega, a wearables engineer at Strava, noted that his company started seeing more problems when bicyclists using the app switched from bike computers clipped onto the front of a bike to using their phones to track heart rate, power, and cadence. The issue, he said, was that the signal now had to go through their bodies to a phone typically carried in a pocket on their back.

I typically run with my phone in a jogging belt around my waist, which means that a heart-rate strap on my chest has to bounce a signal off the ground to reach my phone. I’ve noticed that the Mio Alpha, a wrist-based heart-rate tracker, seems to keep a more solid connection—perhaps because it has line of sight to my phone on my waist. Other runners who carry their phone in a back pocket or on an armband might have different results with different devices.

Healthy Problems To Have

There’s a lot that can go wrong with today's fitness trackers, from the batteries, radios, and sensors in the hardware, to the software on the device and on the phone, to the Internet services they connect to.

But if these devices are going to reach the mass market, and bring the promised benefits, the industry will come together to solve them.

Apple is reportedly interested in the health and fitness arena, and has been hiring experts who could potentially help it launch its own products and services in the field. If the iOS 7.0.4 problems are real and having a negative impact on users and developers, that’s a discouraging sign for Apple’s nascent efforts. As it found in the early days of the iPhone, bringing “it just works" simplicity to a world of wirelessly connected smart devices is a lot harder than it sounds.