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A sense of feeling of anticipation. I can see the cold breath emanating from my competitors as they perform the "pre-race" jiggle on the starting line.

A swift movement of the hips.

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

Oh, hang on. I must start my device. As does the guy next to me.

The person behind us expresses impatience. I refuse to go until… yes! GPS ready, and I'm running.

In the mele, it's hard to find a wrist without a wearable on it. And it's not just us participants who rely on them.

This is a explosive, multi-billion dollar sector. Names like Garmin are prevalent, all offering an extensive selection of diverse versions to fit a variety of budgets. According to how high tech the model you go for, prices can range from £100 to a small fortune.

"It drives me insane, it's impossible to switch off."

"It comforts me… It acts as a companion guiding me."

"Stop telling me about a restless night."

Just some of the responses I've had from like-minded device users when I ask what they feel about theirs.

A Sea of Statistics

My current opinion on my own device? Currently, annoying. It's reporting my speed is wrong, making me wonder whether the foliage I'm passing under are disrupting my location tracking.

A vast number of us strap these little devices onto our wrists and use them all day and night, ostensibly comfortable with the fact they're perpetually recording us.

Gone are the days when we relied on them only to give us an rough count of our pedometer reading. Currently, they can measure our sleep patterns, blood pressure, glucose levels, our body battery.

It's a challenge to find a bodily function they aren't designed to measure.

But are they able to do what they advertise? And are the numbers we obsess over a true reflection of the truth? Do they enhance our mental and physical wellbeing, or do the multitude of measurements and constant notifications just increase our sense of overwhelm?

Addiction or Aid?

"I do get a quite preoccupied with mine," a wearer confesses.

While she values how her device records her workouts, she finds some of its other features "excessive" at times - a feeling that became apparent during a pregnancy.

Prior to discovering she could adjust the settings, her smartwatch constantly alerted her she was being insufficiently productive enough. Now, the watch keeps telling her she's had a poor sleep score.

"I've got a young baby, there's no point to be informed I've not slept," she says. "I know that perfectly well."

Why doesn't she just stop wearing it?

"I suppose I could, perhaps, but I've got this complicated dynamic with it," she continues. "I appreciate it for its fitness insights, I sometimes question whether the myriad other functions it can now do is maybe excessive for me."

The Technology Behind the Tracking

Different brands of smartwatch has its own proprietary way of monitoring your vitals and processing your data, but the most use detectors on the back of the watch.

They commonly emit minute LED lights onto your arm which can observe capillary action, detecting your BPM. More advanced devices detect changes in the bioimpedance that passes over the skin to get an idea of your nervous system activity.

A Fine Balance

A data scientist says that overall for smartwatches, it's a "fine balance" - while the ever-evolving tech could actually aid early diagnosis, "identifying issues before we show symptoms", it could also turn us the tracked into the "anxious healthy".

He points out that some of the latest wearables can conduct tests like heart rhythm analysis, which continuously monitor how normal the heart is. They can flag if someone is experiencing atrial fibrillation (AF), where there is erratic electrical activity in the heart causing an uneven pulse.

This does not mean someone is imminently going to suffer a cardiac event, but it can give an advance notice they might be more at risk of a stroke in the long term.

But how to understand these figures is not straightforward. The expert worries that as additional features are added, people may not be able to fully understand their data.

"I have some doubts that having the capacity to monitor so many things is such a good idea," he says.

A clinical psychologist specialising in wearable tech concurs. Her work into the impact of wearable tech on a set of cardiovascular 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 medical services".

She noted a pattern with her patients - they spotted a concerning reading on their watch. They grew concerned. Their heart rate went up. They got increasingly anxious. They re-examined the data, and their anxiety went up again.

"When people are presented with numbers about ourselves that we don't really understand then, naturally, we are going to want to know more," the psychologist says. "We monitor, we obsess - it becomes a vicious cycle."