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At the start of this year’s New York City Marathon, three people stared at me and tried to figure out why I didn’t have a heartbeat. I had one, of course. It just wasn’t registering on the puck-shaped device taped to my body that was part of Performance Metrics, a tracking system created by the marathon’s sponsor, TCS, and not commercially available. It was supposed to be able to spit out my heart rate, breathing rate, pace and speed in real time.

“I guess I’m dead,” I said.

I was one of a group of volunteers wearing the device because I wanted to see whether tracking how these stats changed over the course of the race would offer any insights into my running.

I normally eschew almost every fitness tracker, running app, fitness data analytics platform and fitness-geared social media website that’s come up in my 11 years of running. During training, I most often wear the cheapest GPS watch Garmin made at the time my previous watch broke — which also was the cheapest GPS watch Garmin made. And I don’t upload those workouts anywhere — I manually log my time and distance into Daily Mile.

But I appear to be in the minority. Eighty-two percent of runners like to have and track all of their running statistics, and 65 percent say it helps them train better, according to Running USA’s 2017 National Runner Survey. And the wearables market in the United States is likely to grow, from $4.8 billion in 2016 to $9.1 billion by 2022, according to Forrester, a market research company.

Data can be helpful, said Dr. Simon Marshall, a coach, performance psychologist and co-author of “The Brave Athlete.”

“One of the cornerstones of improving is self-monitoring,” he said. Wearables provide that information — and it’s also objective. You may feel one way, while the data your body spits out may say another. Wearables “reduce our tendency to rely on anecdotes, feelings and impressions and all the other reasons human brains interpret information in a biased way,” he said.

All that data, however, can exacerbate issues athletes already have with conditions like anxiety. “Sometimes gadgets or the ability to quantify what you’re doing — they can be enablers of those traits,” Dr. Marshall said. “They can bring out the worst in some people’s personalities and can lead to less happiness, not more.” An intense focus on data can “disconnect you from the experience of running,” he said.

Andrew Begley, coach at the Atlanta Track Club who oversees its Olympic Development program, said that sometimes runners can be hurt by the numbers that wearables produce if they focus on just one aspect of their training and forget the other factors that make for a strong runner.

“They get it in their head the way to be a better runner is to work harder, to run faster. It’s not really about that. It’s about recovery. It’s about making sure you’re getting enough sleep. It’s eating well,” he said. “As a coach, you have to remind them not to focus so much on that one aspect of their training, and help them focus on the whole picture.”

And some studies show that tracking devices can hamper goals. A recent study published in The Journal of American Education found that many teenagers who wore activity trackers got frustrated with them, feeling discouraged if they didn’t fit in 10,000 steps a day and became less motivated to be active than before they had the device. A 2016 JAMA study also found that activity trackers can undermine weight loss goals.

And of course if we don’t use them, which many people don’t, the only purpose they’ll serve is as a dust catcher. Dr. Louis Manza, professor and chair of psychology at Lebanon Valley College and an ultrarunner, got a Fitbit as a gift last year but never really got past the initial setup phase. “I was playing around with it for an hour trying to set the thing up,” he said, before deciding, “I don’t need this.”

While he says that experienced runners can benefit from getting objective data on their progress via an activity tracker, he doubts their value for new runners. “Someone who’s just starting, they’ve got to get into the rhythm of just moving,” he said. “I don’t know how much it’s really going to help them if their primary goal is putting one foot in front of the other and getting in the habit of getting out the door and exercising.”

In addition, for many people, the data can be overwhelming and distract you from reading your body’s own natural feedback.

“When you’re listening to your body, you’re getting more out of the workout, whatever that experience is. If you’re relying on your technology for everything, you’re not listening to what your body is trying to do and not getting the best benefit from the workout,” Dr. Manza said.

So did the Performance Metrics tracker offer any insights about my running? Despite stopping four times to retape the puck to my body and reboot the device, it still didn’t record a heartbeat. That resulted in a very frustrated runner and Performance Metrics team, and two large chafing spots on my chest that still hadn’t quite healed a month later.

The device did, however, stay put on Tiki Barber, the former New York Giants running back, who had tested it out twice before running the marathon. He found that if he wore a strap around his body and shoulder it would stay in place during his run.

He has run seven marathons and said he hoped that the data would help him figure out why he has always bonked around mile 18. “Does my heart rate pick up? Does my sweat rate increase at some point? What about my body temperature? Does my posture change and I’m putting more stress on different parts of my body? That’s what I wanted to find out,” he said.

Mr. Barber has yet to analyze the data but says he hopes to wear the tracker again in his next marathon. I, however, will probably pass.