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There's a building tension. Visible is the frosty air emanating from my rivals as they execute the "about to run" jiggle on the start line.

A rapid flick of the hips.

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

Wait a second. I must sort my tracker. The same goes for the person next to me.

The person in the line expresses impatience. I refuse to go until… done! GPS ready, away I go.

In the mele, it's difficult to spot a person without a wearable on it. And this isn't only us runners who rely on them.

This is a booming, multi-billion pound market. Names like Samsung Galaxy dominate, each with an extensive selection of various versions to fit a variety of lifestyles. Based on how advanced the device you select, costs can start from £100 to a significant investment.

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

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

"Please don't notify me I've experienced a restless night."

Just some of the responses I've had from fellow smartwatch wearers when I inquire what they feel about theirs.

The Data Dilemma

My thoughts on my own device? Right now, annoying. It's indicating I'm off pace, leading me to doubt whether the overhead branches I'm running below are disrupting my GPS connection.

A vast number of us fasten these little gadgets onto our arms and wear them constantly, seemingly unconcerned with the fact they're constantly tracking us.

Long past are the days when we relied on them only to give us an idea of our step count. Now, they can measure our nightly rest, blood pressure, glucose levels, our recovery score.

It's tricky to find a health indicator they aren't designed to measure.

But do they do what they claim to do? And are the statistics we analyse a faithful picture of the truth? Do they enhance our overall health, or do the avalanche of metrics and motivational messages just add to our sense of overwhelm?

A Love-Hate Relationship

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

While she appreciates how her device monitors her runs, she finds some of its other functions "excessive" at times - a feeling that became apparent during a pregnancy.

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

"I have a infant, I don't need to be notified I've not slept," she says. "I'm acutely aware all too clearly."

Is it not possible to just take it off?

"I could, I suppose, but I have this love-hate relationship with it," she says. "I appreciate it for its fitness insights, I sometimes question whether the myriad other functions it can now do is possibly overkill for me."

The Technology Behind the Tracking

Every device of smartwatch has its own proprietary way of monitoring your bodily functions and interpreting your data, but the majority use detectors on the back of the watch.

They usually shine minute LED lights onto your wrist which can detect capillary action, recording your heartbeat. Higher-end devices measure changes in the skin conductance that runs through the skin to get an idea of your nervous system activity.

The Professional Viewpoint

A data scientist says that overall for smartwatches, it's a "delicate equilibrium" - while the ever-evolving tech could potentially prevent illness, "detecting disease before we show symptoms", it could also turn us the tracked into the "worried well".

He points out that some of the latest wearables can conduct tests like medical-grade monitoring, which regularly monitor how healthy the heart is. They can flag if someone is experiencing an irregular rhythm, where there is abnormal impulses in the heart causing an uneven pulse.

This does not automatically signal someone is imminently going to suffer a cardiac event, but it can give an preliminary indication they might be more at risk of a stroke in the future.

But how to understand these numbers is complex. The expert worries that as additional features are incorporated, people may not be able to fully comprehend their data.

"I'm not entirely convinced that the ability to monitor so many metrics is such a positive development," he says.

A health researcher focusing on cardiology echoes this sentiment. Research into the effect of wearable tech on a set of heart condition patients suggested a noticeable percentage of those who were given devices to monitor their cardiac function experienced increased anxiety and were "far more likely to use medical services".

She observed a cycle with her patients - they spotted a worrying figure on their watch. They felt anxious. Their heart rate increased. They got more worried. They checked again, and their heart rate rose further.

"If we see stats about ourselves that we can't properly interpret then, understandably, we are going to want to know more," the psychologist says. "We check, we obsess - it becomes a self-fulfilling prophecy."