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There's a feeling of anticipation. Apparent is the frosty air coming from my competitors as they perform the "pre-race" jiggle on the beginning point.

A rapid flick of the hips.

I'm lined up for my local Saturday morning race and I mean business. Three, two, one...

Hold on. I must start my watch. As does the runner alongside me.

The person in the line sighs. I won't start until… yes! Signal acquired, I'm off.

During the scramble, it's challenging to find a arm without a smartwatch on it. And this isn't only us runners who rely on them.

This is a booming, multi-billion dollar market. Companies like Garmin are prevalent, all offering an wide selection of diverse versions to suit a variety of budgets. Based on how feature-packed the watch you go for, costs can vary between £100 to thousands of pounds.

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

"It comforts me… It's like a friend supporting me."

"Stop telling me I've experienced a poor sleep."

Just some of the comments people have shared from other tracker enthusiasts when I question what they their opinion is on theirs.

A Sea of Statistics

My thoughts on mine? Right now, annoying. It's reporting I'm off pace, leading me to doubt whether the overhead branches I'm passing under are disrupting my satellite signal.

Millions of us attach these little monitors onto our wrists and keep them on 24/7, seemingly at ease with the fact they're continuously recording us.

Gone are the days when we used them exclusively to give us an rough count of our daily steps. Now, they can analyse our sleep quality, stress levels, glucose levels, our body battery.

It's tricky to find a physical metric they don't track.

But are they able to do what they claim to do? And are the statistics we scrutinise a faithful picture of our actual health? Do they boost our overall health, or do the multitude of readings and cheerleading alerts just increase our sense of overwhelm?

A Love-Hate Relationship

"I do get a bit preoccupied with mine," one user confesses.

While she appreciates how her device records her runs, she finds some of its other functions "daunting" at times - a feeling initially realised during a pregnancy.

Prior to discovering she could adjust the settings, her smartwatch constantly alerted her she was failing to be active enough. In a new phase, the watch frequently reports her she's had a restless night.

"I have a young baby, I don't need to be told I'm tired," she says. "I'm acutely aware only too well."

Couldn't she just take it off?

"It's possible, I suppose, but I've got this complicated dynamic with it," she explains. "I appreciate it for its fitness insights, but I'm unsure whether all the other things it can now do is maybe excessive for me."

The Technology Behind the Tracking

Each model of smartwatch has its own unique way of tracking your bodily functions and analysing your data, but the vast bulk use sensors on the underside of the watch.

They typically shine tiny, coloured LED lights onto your skin which can observe capillary action, recording your pulse rate. Sophisticated devices analyse changes in the bioimpedance that runs through the skin to get an idea of your nervous system activity.

Expert Perspectives

A data scientist says that in general for smartwatches, it's a "fine balance" - while the continuously improving tech could potentially prevent illness, "spotting abnormalities before we feel unwell", it could also turn us device users into the "concerned but fine".

He points out that the most advanced wearables can conduct tests like medical-grade monitoring, which regularly monitor how normal the heart is. They can notify if someone is experiencing a heart arrhythmia, where there is irregular impulses in the heart causing an arrhythmia.

This does not mean someone is about to have a cardiac event, but it can give an early warning they might be more at risk of a stroke in the long term.

But how to interpret these figures is not straightforward. The expert fears that as further capabilities are introduced, people may not be able to fully comprehend their data.

"I have some doubts that having the capacity to monitor so much data is such a beneficial thing," he says.

A health researcher specialising in patient behaviour echoes this sentiment. Her work into the effect of wearable tech on a set of cardiovascular patients suggested a significant portion of those who were given devices to monitor their cardiac function experienced heightened worry and were "more inclined to use doctor's time".

She observed a vicious circle with her patients - they noticed a worrying figure on their watch. They became worried. Their heart rate went up. They got more worried. They re-examined the data, and their anxiety went up again.

"When people are presented with numbers about ourselves that we can't properly interpret then, naturally, we are going to want to know more," the psychologist says. "We look, we check again - it becomes a feedback loop."