Health watch: How much health data is healthy? 

It's never been easier to track what's happening in our bodies, thanks to fast-evolving technology. But is it helpful to keep such a close eye on our physical condition? 

Just because we can track almost every aspect of our health doesn’t mean we should. Picture: iStock

Counting steps and assessing sleep were previously the key features of a fitness tracker. But now you can also monitor your heart rhythm, menstrual cycle, and gut health and not just inactivity and tiredness.

But do we really need to keep such close tabs on every aspect of our health, via smartwatches and apps?

In the International Journal of Environmental Research and Public Health, researchers from Daemen University, in New York, and from the University of Ottawa, looked at the pros and cons of health trackers. 

They concluded that while trackers can be “powerful and informative tools”, the information can also be misleading and inaccurate.

“Technology is continuously improving,” says Jennifer Sheid, associate professor of physical therapy at Daemen University and lead author of the paper. 

“But there is a lot of variation in the reliability and validity of different devices and the different components of health that they measure.”

Just because we can track almost every aspect of our health doesn’t mean we should. Sleep tracking is notorious for creating an unhealthy fixation with poor sleep, which can make sleep even more fractured.

Dearbhla McCullough, a psychologist who works in Belfast, London, and Co Mayo, says she sees many clients for whom data has become a source of anxiety. 

“Getting stressed when your tracker tells you that you haven’t slept or taken enough steps is not going to help your emotional health,” McCullough says. 

“By all means track data if you find it useful and motivating, but my advice would be to take a day without tracking anything occasionally.”

Beyond steps, heart rate, and exercise minutes, what other health data is worth logging?

From blood sugar to heart arrhythmia, technology means we can track all types of health issues

Blood sugar

Continuous glucose monitors (CGM) were developed to track the blood sugar of people who have diabetes, but are now being used by anyone who wants to pay a premium for real-time feedback on blood-sugar responses to food, exercise, stress, and sleep. 

A small sensor, attached underneath the skin of the upper arm (or stomach), measures how much sugar is in the fluid surrounding your cells. It does this every few minutes, with data sent to an app on your phone.

The sensors need to be replaced after seven to 14 days, although you have to subscribe to a plan to get the full track service.

Worth doing?

It’s claimed that by better understanding your blood-sugar responses, you will learn which foods help maintain an even keel of energy levels and wave goodbye to bad eating habits and extra pounds. 

“With diabetes, your blood sugar does get to a level where it can cause harm, and it is essential to track it so that you can adjust insulin doses,” says Dr Nicola Guess, an academic dietician and researcher at the University of Oxford.

However, she says that there is no evidence that tracking blood-glucose peaks and troughs is beneficial and says that the pancreas does a great job of regulating the release of sugar in the body to keep it within normal levels.

Menstrual cycle

Dozens of apps, such as the popular Flo Period and Ovulation Tracker and Clue Period, promise to track a woman’s menstrual cycle and help with everything from planning conception to monitoring pregnancy. 

Some, such as FitrWoman, NikeSync and CycleMapping, claim to help women sync their workouts and their exercise recovery with the hormonal phases of their monthly cycle.

Worth doing?

In a review of 300 studies of 73 apps, researchers reporting in the journal Human Fertility found that of the 73% of fertility apps offering ovulation predictions, only 20% were accurate. 

The researchers noted “severe limitations when it comes to recording menstrual-cycle variability and accurate fertility prediction”.

Studies in the Journal of Applied Physiology found no evidence that adapting workouts to menstrual cycles by using an app makes any difference. 

“Hormone levels can vary substantially,” said lead author Mai Wageh, a PhD candidate in the Department of Kinesiology at McMaster University, Canada, and lead author of the paper. 

“Not just between two women, but within one woman from one cycle to the next."

Researchers noted “severe limitations when it comes to recording menstrual-cycle variability and accurate fertility prediction”.

Gut health

Your microbiome, the vast community of microorganisms, including fungi, bacteria and viruses in the gut, plays a vital role in wellbeing.

Researchers have identified ‘good’ and ‘bad’ bacteria that help or hinder our health. An imbalance of gut bacteria has been associated with digestion, skin and stomach issues, tiredness, weight gain, and mood swings.

Some apps offer advice based on symptom and food-intake data provided by the user; others offer personalised advice based on the results of faecal stool samples tested in a lab for results of your unique gut bacteria.

Worth doing?

While the gut microbiome acts like an important organ in the body, it is not yet known if tiny modifications to this complex ecosystem of bacteria through diet achieve anything meaningful.

“There is no standard microbiome composition to compare against,” says Guess. “We don’t know the cause and effect of good and bad bugs on weight and health and we know much less about whether modifying the gut microbiome is going to have any effect on someone’s weight or predisposition to a condition like type 2 diabetes.”

Even accurate devices do not continuously monitor for Atrial Fibrillation

Heart arrhythmia

Atrial fibrillation (AF) occurs when electrical impulses that trigger muscle contractions of the heart misfire chaotically. 

The Irish Heart Foundation (IHF) says 25% of the over-50s have the condition, and a recently published study shows that 11% of over-65s in Ireland suffer from AF, but in about 33% of patients, there are no symptoms. 

Left undiagnosed or untreated, it raises the risk of stroke and heart failure.

Worth doing?

“The only part of any fitness tracker that has been approved as a medical device in some watches, for example, the Apple Watch Series 4 or later, is the photoplethysmography technology that is used to screen for atrial fibrillation,” Sheid says.

However, AF is not the only irregular heart rhythm — others include atrial flutter, ventricular tachycardia, and ventricular fibrillation — yet it is the only arrhythmia that existing technology monitors.

Also, even accurate devices do not continuously monitor for AF and measurements are taken intermittently, which means it could still be missed.

“Overall, though,” says Sheid, “the consensus is that a tracker might detect AF in someone who is otherwise unaware of it and is therefore worthwhile.”