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There's a nervous excitement. Apparent is the chilled vapour coming from my rivals as they do the "pre-race" jiggle on the start line.

A swift movement of the hips.

I'm lined up for my local 5km community parkrun and I mean business. The countdown begins...

Oh, hang on. I must adjust my tracker. The same goes for the runner beside me.

The person behind us expresses impatience. I'm not moving until… done! GPS ready, and I'm running.

Amidst the crowd, it's difficult to see a arm without a smartwatch on it. And this extends beyond us athletes who use them.

We're witnessing a booming, massive industry. Names like Apple Watch dominate, each with an broad range of diverse models to cater to a variety of needs. Based on how feature-packed the device you go for, price tags can vary between an affordable sum to a small fortune.

"It makes me crazy, I'm unable to relax."

"It reassures me… It's like a supporter guiding me."

"Please don't notify me about a restless night."

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

The Data Dilemma

My thoughts on mine? Currently, irritating. It's indicating I'm not hitting my target, making me wonder whether the overhead branches I'm running below are interfering with my location tracking.

Millions of us fasten these small devices onto our wrists and use them all day and night, seemingly at ease with the fact they're continuously recording us.

A distant memory are the days when we relied on them solely to give us an rough count of our step count. Currently, they can measure our sleep patterns, blood pressure, glucose levels, our body battery.

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

But do they do what they claim to do? And are the numbers we scrutinise a true reflection of reality? Do they boost our mental and physical wellbeing, or do the avalanche of readings and motivational messages just increase our daily stresses?

A Love-Hate Relationship

"I do get a bit preoccupied with mine," an individual reveals.

While she loves how her device monitors her workouts, she finds some of its other capabilities "overwhelming" at times - a feeling that became apparent during a significant period.

Prior to discovering she could change its configuration, her smartwatch kept telling her she was not being active enough. In a new phase, the watch insists her she's had a bad night's sleep.

"I am caring for a six-month old, there's no point to be told my sleep was poor," she says. "That fact is all too clearly."

Why doesn't she just stop wearing it?

"It's possible, theoretically, but I have this complicated dynamic with it," she continues. "I appreciate it for its workout tracking, I just wonder whether all the other things it can now do is perhaps overkill for me."

The Technology Behind the Tracking

Every device of smartwatch has its own proprietary way of monitoring your health metrics and processing your data, but the vast bulk use detectors on the underside of the watch.

They usually project tiny, coloured LED lights onto your skin which can observe capillary action, detecting your heartbeat. Sophisticated devices analyse changes in the electrical current that flows through the skin to gauge your recovery state.

A Fine Balance

A data scientist says that for most people for smartwatches, it's a "delicate equilibrium" - while the continuously improving tech could actually aid early diagnosis, "detecting disease before we notice anything", it could also turn us the tracked into the "worried well".

He points out that the most advanced wearables can perform tests like heart rhythm analysis, which continuously monitor how healthy the heart is. They can flag if someone is experiencing an irregular rhythm, where there is abnormal electrical activity in the heart causing an irregular heartbeat.

This does not necessarily indicate someone is imminently going to suffer a heart attack, but it can give an early warning they might be more vulnerable of a stroke in the years to come.

But how to interpret these readings is complicated. The expert worries that as more functions are introduced, people may struggle to fully contextualise their data.

"I'm not entirely convinced that being able to monitor so many metrics is such a good idea," he says.

A clinical psychologist focusing on wearable tech agrees. A study into the influence of wearable tech on a cohort of individuals with health issues suggested a minority of those who were given devices to monitor their cardiac function experienced increased anxiety and were "far more likely to use healthcare resources".

She noted a cycle with her patients - they saw a alarming metric on their watch. They felt anxious. Their BPM increased. They got increasingly anxious. They checked again, and their reading increased again.

"When people are presented with stats about ourselves that we can't properly interpret then, naturally, we are going to seek clarification," the psychologist says. "We monitor, we obsess - it becomes a self-fulfilling prophecy."