A cardiologist says fitness trackers such as Fitbits can increase anxiety among some people if they 'interpret the numbers incorrectly'.
He says that can lead to unnecessary trips to the doctor.
Dr Dermot McCaffrey, consultant cardiologist at the Beacon Hospital in Dublin, says they've seen people attend their rapid access clinics simply because of the 'numbers directed back to them from their wrist'.
He says fitness trackers can be useful in general, but people need to be aware of the limitations.
The popularity of wearable fitness technology has soared in recent years, while the ongoing pandemic has encouraged many people to walk or run more to keep fit.
Dr McCaffrey told Newstalk Breakfast these devices are giving people a lot of information.
He said: "[People are] becoming heart aware - which is a good thing.
“But people are seeing numbers directed back to them from their wrist, and how it’s they’re interpreting them. We’re seeing people coming in - either referred by a GP or self-referring - into our rapid access clinic, saying they were just sitting there watching TV and the tracker showed their heart rate go up to 120.
“Trackers I think are useful - they’re encouraging people to exercise, and do a certain amount of steps per day.
"But in a certain group of people who may have some anxiety… they may interpret those numbers incorrectly."
He said people getting worried or anxious can in turn make their heart rate become higher and higher.
Dr McCaffrey said there are occasional times trackers will pick up issues.
However, he said if people are feeling OK despite unusual data it may not be a cause for concern.
He explained: “If it keeps happening, then yes attend your GP - there may be an explanation for it.
“It can pick up things like thyroid disease, which makes your heart go fast.
“But for every average heart rate of 70, somebody’s normal heart rate is 50 and somebody’s heart rate is 90."
Another issue is that people may feel 'judged' if a group is sharing their steps data - something that Dr McCaffrey suggested can lead to people actually feeling less well about themselves.
He said: “I’m an advocate of a thing called fat and fit - that’s not worrying about if you’re fat, but instead just getting out and walking.
"Eventually, after six months of walking, you will be less fat but you’ll be fit - not concentrating so much on weight, but more about getting out walking."