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A sense of feeling of anticipation. Apparent is the frosty air emanating from my rivals as they execute the "pre-race" shuffle on the start line.

A quick twitch of the hips.

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

Wait a second. I have to sort my watch. So does the runner next to me.

The person waiting tuts. I refuse to go until… done! Signal acquired, I'm off.

During the scramble, it's challenging to spot a arm without a smartwatch on it. And this extends beyond us participants who rely on them.

It's a thriving, multi-billion pound sector. Names like Garmin dominate, each with an extensive array of diverse models to cater to a variety of needs. According to how high tech the watch you select, costs can vary between an affordable sum to a significant investment.

"It drives me insane, I can't relax."

"It comforts me… It feels like a friend encouraging me."

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

A small sample of the comments I've had from fellow tracker enthusiasts when I ask what they their opinion is on theirs.

The Monitoring Conundrum

My feelings on my own device? Currently, frustrating. It's indicating I'm not hitting my target, causing me to question whether the trees I'm running below are blocking my satellite signal.

Countless individuals of us attach these compact monitors onto our wrists and wear them all day and night, ostensibly at ease with the fact they're perpetually recording us.

Gone are the days when we used them solely to give us an estimation of our step count. Now, they can measure our sleep patterns, heart rate, oxygen saturation, our body battery.

It's difficult to find a bodily function they don't track.

But are they able to do what they say they do? And are the data points we analyse a accurate representation of the truth? Do they boost our overall health, or do the multitude of readings and motivational messages just increase our sense of overwhelm?

A Love-Hate Relationship

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

While she values how her device records her workouts, she finds some of its other features "excessive" at times - a feeling first discovered during a significant period.

Before she realised she could put it into a specific mode, her smartwatch kept telling her she was failing to be productive enough. Now, the watch keeps telling her she's had a restless night.

"I have a infant, I don't need to be notified I've not slept," she says. "I know that perfectly well."

Couldn't she just remove it?

"It's possible, theoretically, but I've got this complicated dynamic with it," she explains. "I love it for its exercise data, I just wonder whether the myriad other functions it can now do is maybe overkill for me."

Inside the Device

Each model of smartwatch has its own novel way of monitoring your bodily functions and analysing your data, but the majority use optical sensors on the underside of the watch.

They commonly shine small, green LED lights onto your skin which can observe blood flow, detecting your BPM. Higher-end devices measure changes in the electrical current that flows through the skin to assess your nervous system activity.

A Fine Balance

A data scientist says that overall for smartwatches, it's a "delicate equilibrium" - while the rapidly advancing tech could realistically save lives, "detecting disease before we notice anything", it could also turn us device users into the "concerned but fine".

He points out that the most advanced wearables can perform tests like electrocardiograms (ECGs), which constantly monitor how normal the heart is. They can flag if someone is experiencing an irregular rhythm, where there is abnormal electrical activity in the heart causing an uneven pulse.

This does not automatically signal someone is on the verge of a heart attack, 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 readings is complicated. The expert fears that as more functions are incorporated, people may not be able to fully contextualise their data.

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

A professor focusing on wearable tech agrees. Her work into the impact of wearable tech on a specific group of cardiovascular patients 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 doctor's time".

She observed a vicious circle with her patients - they saw a concerning reading on their watch. They felt anxious. Their pulse increased. They got increasingly anxious. They looked a second time, and their reading went up again.

"When people are presented with data about ourselves that we don't really understand then, naturally, we are going to want to know more," the psychologist says. "We check, we obsess - it becomes a vicious cycle."