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An atmosphere of building tension. I can see the chilled vapour exhaled by my competitors as they perform the "starting line" shuffle on the starting line.

A rapid movement of the hips.

I'm at my local 5km community parkrun and I'm serious. Three, two, one...

Wait a second. I have to start my device. So does the guy alongside me.

The person waiting sighs. I refuse to go until… there! GPS ready, away I go.

In the mele, it's difficult to find a wrist without a smartwatch on it. And this extends beyond us athletes who use them.

It's a explosive, multi-billion dollar industry. Brands like Samsung Galaxy are prevalent, all offering an broad range of various devices to suit a range of needs. According to how feature-packed the device you select, price tags can vary between £100 to a small fortune.

"I find it infuriating, I'm unable to stop checking."

"It comforts me… It feels like a companion guiding me."

"I wish it wouldn't say I've experienced a restless night."

A small sample of the reactions I've received from like-minded tracker enthusiasts when I inquire what they their opinion is on theirs.

A Sea of Statistics

My current opinion on my own device? Currently, frustrating. It's telling me my speed is wrong, making me wonder whether the overhead branches I'm running below are disrupting my satellite signal.

Countless individuals of us attach these little gadgets onto our arms and use them 24/7, ostensibly at ease with the fact they're continuously monitoring us.

Long past are the days when we depended on them exclusively to give us an idea of our pedometer reading. Currently, they can measure our sleep patterns, stress levels, oxygen saturation, our body battery.

It's a challenge to find a physical metric they aren't designed to measure.

But can they do what they say they do? And are the numbers we obsess over a accurate representation of our actual health? Do they boost our daily wellness, or do the avalanche of readings and cheerleading alerts just increase our sense of overwhelm?

A Complicated Bond

"I find myself getting a quite fixated with mine," a wearer confesses.

While she values how her device records her exercise, she finds some of its other features "daunting" at times - a feeling that became apparent during a significant period.

Until she found out she could put it into a specific mode, her smartwatch kept telling her she was being insufficiently active enough. Later on, the watch frequently reports her she's had a poor sleep score.

"I have a infant, it's unnecessary for me to be informed I've not slept," she says. "That fact is perfectly well."

Is it not possible to just take it off?

"It's possible, theoretically, but I have this push-pull dynamic with it," she explains. "I appreciate it for its workout tracking, but I'm unsure whether all the other things it can now do is maybe too much for me."

How Do They Work?

Each model of smartwatch has its own proprietary way of measuring your health metrics and interpreting your data, but the most use optical sensors on the underside of the watch.

They typically shine tiny, coloured LED lights onto your arm which can observe blood flow, identifying your BPM. Higher-end devices analyse changes in the skin conductance that runs through the skin to assess your nervous system activity.

The Professional Viewpoint

A data scientist says that in general for smartwatches, it's a "difficult line" - while the continuously improving tech could realistically save lives, "spotting abnormalities before we notice anything", it could also turn us device users into the "concerned but fine".

He points out that newer wearables can conduct tests like electrocardiograms (ECGs), which continuously monitor how normal the heart is. They can flag if someone is experiencing a heart arrhythmia, where there is erratic signals in the heart causing an arrhythmia.

This does not necessarily indicate someone is about to have a cardiac event, but it can give an early warning they might be more at risk of a blood clot in the years to come.

But how to interpret these figures is complex. The expert worries that as more functions are added, people may find it hard to fully understand their data.

"I remain sceptical that being able to monitor so many metrics is such a positive development," he says.

A health researcher specialising in wearable tech echoes this sentiment. Research into the impact of wearable tech on a set of individuals with health issues suggested a noticeable percentage of those who were given devices to monitor their condition experienced greater stress and were "had a higher tendency to use medical services".

She observed a cycle with her patients - they saw a concerning reading on their watch. They grew concerned. Their pulse increased. They got even more concerned. They looked a second time, and their anxiety went up again.

"When people are presented with stats about ourselves that we don't really understand then, of course, we are going to become concerned," the psychologist says. "We look, we check again - it becomes a vicious cycle."