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A sense of feeling of anticipation. I can see the chilled vapour coming from my competitors as they perform the "starting line" shuffle on the start line.

A swift twitch of the hips.

I'm participating in my local weekly parkrun event and I'm focused. Three, two, one...

Hold on. I have to sort my tracker. As does the person alongside me.

The person in the line tuts. I'm not moving until… there! Signal acquired, away I go.

In the mele, it's hard to spot a person without a fitness tracker on it. And this isn't only us athletes who wear them.

This is a explosive, multi-billion dollar market. Companies like Garmin dominate, all offering an extensive range of diverse devices to cater to a variety of needs. Based on how high tech the device you select, price tags can start from £100 to a significant investment.

"I find it infuriating, it's impossible to relax."

"It provides solace… It's like a supporter supporting me."

"Please don't notify me I've had a poor sleep."

A small sample of the comments I've had from other smartwatch wearers when I ask what they think of theirs.

A Sea of Statistics

My thoughts on mine? At this moment, frustrating. It's telling me I'm off pace, making me wonder whether the trees I'm passing under are disrupting my GPS connection.

Countless individuals of us strap these compact devices onto our arms and keep them on 24/7, ostensibly unconcerned with the fact they're constantly monitoring us.

Gone are the days when we relied on them solely to give us an idea of our pedometer reading. Today, they can analyse our nightly rest, stress levels, glucose levels, our VO2 max.

It's a challenge to find a physical metric they fail to monitor.

But do they do what they claim to do? And are the statistics we scrutinise a accurate representation of our actual health? Do they enhance our overall health, or do the plethora of measurements and cheerleading alerts just add to our daily stresses?

Addiction or Aid?

"I become a bit preoccupied with mine," a wearer reveals.

While she appreciates how her device tracks her runs, she finds some of its other functions "excessive" at times - a feeling first discovered during a pregnancy.

Prior to discovering she could change its configuration, her smartwatch repeatedly informed her she was not being productive enough. Later on, the watch keeps telling her she's had a bad night's sleep.

"I've got a six-month old, there's no point to be informed I've not slept," she says. "That fact is perfectly well."

Why doesn't she just remove it?

"It's possible, theoretically, but I have this complicated dynamic with it," she explains. "I value it for its workout tracking, I sometimes question whether the myriad other functions it can now do is maybe too much for me."

The Technology Behind the Tracking

Different brands of smartwatch has its own proprietary way of tracking your bodily functions and processing your data, but the vast bulk use sensors on the reverse of the watch.

They usually emit tiny, coloured LED lights onto your skin which can observe blood flow, detecting your pulse rate. Higher-end devices measure changes in the electrical current that runs through the skin to get an idea of your nervous system activity.

Expert Perspectives

One expert says that overall for smartwatches, it's a "delicate equilibrium" - while the continuously improving tech could realistically aid early diagnosis, "identifying issues before we notice anything", it could also turn us device users into the "concerned but fine".

He points out that some of the latest wearables can perform tests like electrocardiograms (ECGs), which continuously monitor how stable the heart is. They can alert if someone is experiencing atrial fibrillation (AF), where there is irregular impulses in the heart causing an uneven pulse.

This does not necessarily indicate someone is about to have a heart attack, but it can give an preliminary indication they might be more vulnerable of a heart problem in the long term.

But how to make sense of these readings is complex. The expert concerns that as further capabilities are incorporated, people may struggle to fully understand their data.

"I'm not entirely convinced that being able to monitor so many things is such a beneficial thing," he says.

A clinical psychologist specialising in patient behaviour echoes this sentiment. A study into the effect of wearable tech on a specific group of individuals with health issues suggested a minority of those who were given devices to monitor their cardiac function experienced greater stress and were "had a higher tendency to use healthcare resources".

She noted a pattern with her patients - they noticed a concerning reading on their watch. They became worried. Their pulse rose. They got more worried. They looked a second time, and their reading increased again.

"If we see numbers about ourselves that we don't really understand then, of course, we are going to seek clarification," the psychologist says. "We look, we obsess - it becomes a self-fulfilling prophecy."