Fitness tracker vs cardiologist: Does your smartwatch know your heart better than your doctor?

From counting steps and calories to measuring heart rate, sleep duration, stress levels, oxygen saturation (SpO2) and activity level, modern wearables offer a range of benefits. Heart rhythm and ECG patterns can also be measured with some smartwatches today. This increasing flow of information about personal health enables people to recognise changes in their bodies and inspires them to consistently improve their health. For some users, the abnormal patterns may also be an early warning to seek medical help.

But how much can we depend on these devices to give us meaningful insight into our hearts? Experts break down what fitness trackers can tell you, where they hit a wall and why they should never take the place of a doctor evaluating your health.

How fitness trackers promote a healthier lifestyle

Dr Sharwari Sudhir Dabhade, Consultant - Internal Medicine, Diabetology & Endocrinology at Madhukar Rainbow Children's Hospital, says fitness trackers provide more than just physical activity data.

“These devices offer far more utilities than a simple weight scale. Modern fitness trackers can collect detailed data about physical activity, sleep, resting heart rate, stress levels, oxygen saturation and recovery patterns that can provide valuable insights into general health - information typically lacking in standard medical care,” she says.

Promoting healthy habits

Healthy habits can be cultivated using fitness trackers, which are ideally suited to effect positive changes in public behaviour. They inform users about things that prompt them to rethink their lifestyles, adopt healthier ones, and let go of bad habits. “Monitoring changes in users' health is also paramount since it allows people to notice their well-being,” says the expert.

Encouraging early medical attention

Wearable devices can detect certain health trends over time and provide early follow-up medical care. The increased resting heart rate, a reduced level of fitness, and decreased activity without any obvious reason can all be warning signs for certain health concerns, such as infections, anaemia, thyroid diseases, dehydration or even uncontrolled diabetes and heart diseases.

“Wearables cannot produce a diagnosis, but when used this way, they can serve as a useful early warning system that then requires more investigation,” says Dr Dabhade.

Know their limits

“Fitness-tracking devices cannot shed their limitations, no matter how helpful the data they gather. Such devices are a source of worry as one of the limitations is that they cannot differentiate between normal physiological variations and serious pathologies,” says Dr Anshul Kumar Jain, Director – Cardiology at the CK Birla Hospital.

Jain says that information from wearables should always be combined with careful interpretation of suspicious symptoms, an individual's medical history, and a clinical examination and tests, if necessary.

Wearables may detect changes in heart health

Jain notes that cardiovascular applications of wearable technology are increasing.

With the ever-changing health and fitness technology landscape, a variety of exercise trackers have evolved into highly advanced blood-circulation-monitoring devices that help consumers track their heart health and receive guidance.

"Wearables today can continuously estimate heart rate, encourage assessment of the variability around that heart rate (HRV), provide an estimation of cardiorespiratory capacity, identify irregularities in heart rhythm or even record ECG. All those features help to identify small changes in the body, which would otherwise go unnoticed without wearables,” he says.

The important thing about wearable devices is the ability to monitor changes rather than getting a single reading. If a high resting heart rate happens all the time, they need to see a doctor. Wearables have already been used to help diagnose some diseases, such as atrial fibrillation.

While wearables can classify people into high- or low-risk categories for a subset of syndromes, they cannot yet substitute for the doctor in other ways.

“While fitness activity tracking devices have some benefits, it is important to appreciate that they should be considered screening and monitoring tools and not diagnostics. You may get a few false alarms due to poor skin contact, excessive sweating, body hair, vigorous movement or a poorly positioned device,” the experts say.

As a result, the user might become unnecessarily anxious or, worse still, develop an addiction to the information provided by wearables. So, in this respect, counselling is necessary to help people understand technological limitations and prevent false alarms caused by alerts or malfunctions.

Notably, wearables may never be a substitute for a clinical examination or investigation, such as a 12-lead ECG, echocardiography, stress tests or blood tests.

The author, Nivedita, is a freelance writer. She writes on health and travel.