🔗 Share this article

There's a nervous excitement. Apparent is the cold breath coming from my rivals as they do the "starting line" jiggle on the starting line.

A swift movement of the hips.

I'm at my local weekly parkrun event and I'm focused. The countdown begins...

Oh, hang on. I need to adjust my tracker. The same goes for the guy beside me.

The person waiting expresses impatience. I won't start until… done! Signal acquired, and I'm running.

During the scramble, it's difficult to find a wrist without a fitness tracker on it. And this isn't only us runners who wear them.

It's a thriving, multi-billion dollar market. Companies like Apple Watch lead the market, all offering an broad array of different devices to fit a variety of lifestyles. Depending on how feature-packed the model you go for, price tags can vary between a hundred pounds to a significant investment.

"It drives me insane, I can't switch off."

"It reassures me… It's like a companion supporting me."

"Stop telling me I've had a poor sleep."

A handful of the comments I've had from fellow device users when I ask what they think of theirs.

The Data Dilemma

My current opinion on my own device? Right now, irritating. It's telling me my speed is wrong, causing me to question whether the overhead branches I'm running below are blocking my location tracking.

Millions of us fasten these little gadgets onto our wrists and use them constantly, apparently at ease with the fact they're constantly tracking us.

Gone are the days when we used them solely to give us an estimation of our pedometer reading. Currently, they can track our nightly rest, stress levels, heart rate variability (HRV), our VO2 max.

It's a challenge to find a bodily function they don't track.

But do they do what they advertise? And are the numbers we scrutinise a faithful picture of reality? Do they boost our overall health, or do the multitude of measurements and motivational messages just contribute to our everyday anxiety?

A Love-Hate Relationship

"I become a bit fixated with mine," one user confesses.

While she loves how her device records her runs, she finds some of its other capabilities "daunting" at times - a feeling initially realised during a pregnancy.

Before she realised she could adjust the settings, her smartwatch repeatedly informed her she was not being active enough. Later on, the watch frequently reports her she's had a poor sleep score.

"I have a young baby, I don't need to be informed I'm tired," she says. "I know that only too well."

Is it not possible to just remove it?

"I suppose I could, theoretically, but I've got this love-hate relationship with it," she continues. "I appreciate it for its fitness insights, I sometimes question whether the additional features it can now do is possibly excessive for me."

How Do They Work?

Different brands of smartwatch has its own novel way of measuring your vitals and interpreting your data, but the majority use sensors on the underside of the watch.

They commonly shine minute LED lights onto your wrist which can detect pulsation, recording your heartbeat. Higher-end devices detect changes in the bioimpedance that passes over the skin to get an idea of your recovery state.

A Fine Balance

A professor says that in general for smartwatches, it's a "delicate equilibrium" - while the ever-evolving tech could realistically aid early diagnosis, "spotting abnormalities before we show symptoms", it could also turn us device users into the "concerned but fine".

He points out that the most advanced wearables can perform tests like medical-grade monitoring, which regularly monitor how normal the heart is. They can alert if someone is experiencing atrial fibrillation (AF), where there is erratic electrical activity in the heart causing an arrhythmia.

This does not necessarily indicate someone is imminently going to suffer a heart attack, but it can give an advance notice they might be more at risk of a stroke in the future.

But how to make sense of these numbers is not straightforward. The expert fears that as more functions are incorporated, people may not be able to fully understand their data.

"I have some doubts that being able to monitor so much data is such a good idea," he says.

A professor focusing on wearable tech concurs. A study into the effect of wearable tech on a cohort of heart condition patients suggested a noticeable percentage of those who were given devices to monitor their heart health experienced heightened worry and were "more inclined to use healthcare resources".

She observed a vicious circle with her patients - they saw a worrying figure on their watch. They felt anxious. Their pulse went up. They got even more concerned. They looked a second time, and their heart rate rose further.

"Upon viewing numbers about ourselves that we don't really understand then, naturally, we are going to seek clarification," the psychologist says. "We look, we re-check - it becomes a vicious cycle."