CHICAGO — Peggy Ellsworth plays pickleball several times a week at a complex in the northwest suburbs.

“It’s a quick game,” Ellsworth said. “So, you don’t feel like you’ve exercised.”

But according to her Apple Watch, Ellsworth burned 600 calories playing pickleball that day.

“It’s actually more than you would think from a game of pickleball,” said Marcin Simpson, another pickleball player.

According to his Apple Watch, Simpson burns about 1,000 calories every time he hits the court.

“A good playing session gives me a good sweat and a good workout,” Simpson said. “So I would think it’s fairly close to being accurate.”

At Cycle Bar in Wilmette, Jeanne Top used to use an Apple Watch to track her workouts.

“I think certain activities it’s more accurate,” Top said.

When she’s not partaking in a spin class, Top often plays golf and walks the course, but when she uses a cart, Top said she thinks it gives her a fair amount of calories that she doesn’t think she is burning, leading to the switch from Apple to a Garmin watch.

Track instructor Tay Miller made the same switch to her her prepare for an upcoming triathlon.

“Based on how much output I’m giving,” Miller said. “I feel that the calories match it a little better than the Apple Watch.”

Turns out, the tools that accurately gather body metrics aren’t quite as portable as an exercise watch.

“Measuring oxygen directly is going to be the best way to measure calorie burn,” said exercise physiologist Kate Amaral. “It’s just not easy to do.”

As the heart rate climbs, so does the rate of oxygen that goes in and out of the body, which can be measured by wearing an oxygen mask that tracks how much of it went in and out of the body during a period of exercise.

“The other usefulness of that test is the heart rate zones,” Amaral said. “So, it gives them the heart rate zones in which they are burning fat, and then fat plus carbohydrates, and then pure carbohydrates, so it can help inform their training.”

Essentially, using a specialized mask combined with a tracking machine on a treadmill will be able to more accurately deliver how many calories you are burning while exercising, versus a wearable watch, which only uses heart rates to measure calories burned and can vary depending on the tech.

“There’s going to be limitations to what something worn on the wrist or on a ring is going to do but I think the technology is there,” said Dr. Joshua Blomgren, a sports medicine physician with Midwest Orthopedics at Rush Hospital. “The incentive is there to make it better and better and more accurate and more useable.”

Still, sports medicine doctors and fitness experts agree that an Apple or Garmin Watch isn’t needed on a walk.

“The key is our body likes to respond to things on a consistent, regular basis,” said Robert Ventura, a professional cyclist and trainer.