Modern smartwatches have evolved into compact health companions, offering real-time insights into:
Heart rate
Stress levels
Sleep patterns
Blood oxygen saturation
With growing awareness of heart health and easier access to advanced care, wearables have become valuable tools for proactive monitoring. However, professional evaluation remains vital. For expert heart rhythm management in Chennai, Dr. Karthigesan Clinic is your trusted choice.
This guide explores:
How smartwatches track key health metrics
Their advantages, accuracy, and limitations
How to interpret the data responsibly
How Smartwatches Track and Alert You to Health Issues
Can smartwatches detect health issues? Yes — smartwatches pack technology contained in the tiny shell on your wrist, including components such as:
Optical sensors — to measure your pulse
Accelerometers — to monitor every movement
Blood oxygen monitor — to measure oxygen levels in the blood
Even an ECG function — to detect irregular heart rhythms
Here’s what smartwatches can tell you:
Atrial Fibrillation (AFib): The top smartwatch versions from Samsung and Apple have received the FDA's clearance for detecting irregular heartbeats, mainly AFib — a condition that significantly raises the risk of stroke and heart failure.
Sleep Apnoea and Sleep Disorders: Smartwatches track heart rate changes, blood oxygen levels, and movement during the night, helping identify patterns that could signal sleep apnoea — a condition marked by repeated pauses in breathing during sleep.
Abnormal Heart Rate: Smartwatches keep a constant check on resting heart rate and issue alerts when it rises too high (tachycardia) or drops too low (bradycardia). Such fluctuations may signal thyroid disorders, underlying cardiovascular issues, or other health conditions that need medical evaluation.
Blood Oxygen Levels: SpO2 sensors track blood oxygen saturation — a measure that can drop during conditions such as asthma and pneumonia. Several documented cases show how smartwatches detected alarmingly low oxygen levels that prompted users to seek urgent medical care for respiratory issues that had gone undetected.
Next — let’s explore the benefits of smartwatch health tracking and how these devices can support proactive well-being.
While not a replacement for professional care, smartwatches provide meaningful benefits:
24/7 Monitoring: Continuous health tracking to offer important insights into long-term health trends
Early Alerts: Real-time notifications to guide users towards preventive action
Lifestyle Motivation: Progress data insights to encourage healthier habits
Ease of Use: Multiple health parameter tracking on a single wrist device to simplify monitoring
When combined with professional medical advice, these insights can meaningfully boost preventive healthcare.
Next, we’ll examine — feature by feature — how accurate smartwatches are and the factors that impact their measurements.
Accuracy and Influencing Factors of Smartwatch Health Tracking
How accurate are smartwatches for health monitoring? Let’s uncover:
Accuracy by Feature
Heart Rate Monitoring: Modern smartwatches can measure light activity and resting heart rate with 95–99% accuracy against medical-grade monitors. Accuracy, however, decreases to 85–90% during “high-intensity” workouts — as factors such as vigorous movement and sweat can affect the performance of optical sensors.
AFib Detection: In internal clinical studies, the Apple Watch ECG app demonstrated sensitivity > 98% and specificity > 99% in detecting AFib. However, due to high false-positive rates, many notifications were sent to individuals without AFib — creating anxiety and often prompting additional medical visits.
Blood Oxygen Monitoring: Smartwatch SpO2 readings can show error margins of around 2–3% when compared with medical-grade pulse oximeters. As the FDA categorises consumer SpO2 monitors as “general wellness” devices instead of medical tools, they undergo less stringent testing standards.
Sleep Tracking: Smartwatches tend to overestimate total sleep duration by 10–20 minutes on average and have difficulty accurately distinguishing between different sleep stages when compared to polysomnography — the clinical gold standard. However, they remain reliable for detecting sleep versus wake periods and tracking sleep patterns over time.
Step Counting: Step counters provide reasonably accurate measurements for regular walking but can be less reliable during activities like weight lifting or cycling. Calorie burn estimates are often imprecise, as they are based on generalised formulas that may not account for individual differences in metabolism.
Factors Affecting Accuracy
Measurements’ accuracy can fluctuate depending on several factors — let’s explore.
Device Quality: Premium smartwatches are equipped with advanced sensors and more sophisticated algorithms — delivering more accurate readings than entry-level/budget devices.
Proper Fit: The smartwatch should fit snugly yet comfortably, correctly positioned above the wrist bone with proper skin contact — a loose fit can lead to inaccurate measurements.
User Characteristics: Wrist size, skin tone, body composition, and tattoos affect the accuracy of the sensors. Some technologies perform more precisely on certain skin tones — an equity issue manufacturers are actively working to address.
Environmental Conditions: Bright sunlight, cold weather, and water exposure can impair optical sensors.
Up next — responsible use of wearable heart data to guide smarter health choices.
How to Use Wearable Heart Data for Better Health Decisions?
Wearable heart data can offer valuable insights — but its true benefit comes from understanding trends, interpreting alerts responsibly, and knowing when to consult a healthcare professional.
Here’s how to use it wisely:
Watch for Trends, Not One-offs: Focus on patterns over time rather than isolated readings — it’s the overall trends that provide the most useful insights for your health decisions.
Listen to Your Body: Always interpret your heart data in the context of your symptoms and overall well-being. Alerts from your smartwatch are useful signals, but your body’s experience should guide your response — use the device as a complement to, not a replacement for, your own awareness.
Get Concerning Data Examined by a Professional: If your smartwatch shows worrisome readings, share the information with your doctor. They can run medical tests to confirm or rule out any issues — ensuring you get accurate insights rather than relying solely on the smartwatch.
Don’t Start or Change Medications on Your Own: Never adjust or start medications based solely on smartwatch readings — always check with a healthcare professional to confirm any concerns and use the data responsibly.
Wear and Set Your Device Properly: Make sure your smartwatch fits securely and is worn correctly to get accurate readings. Check settings and enable relevant features to ensure the data reflects your true activity and health metrics.
Remember: Smartwatches are not intended for diagnosis and should serve as a supplement — not a substitute — for routine medical care.
Beyond the Numbers: Real Heart Health Starts Here
Your smartwatch gives you something previous generations never had — a constant window into what's happening inside your body. Even so, many people still wonder, “Can smartwatches detect heart problems effectively?” Yes, but they are far from perfect — while they provide useful insights, they have limitations and cannot replace professional medical evaluation. However, these devices can nudge you towards healthier habits and sometimes catch problems early.
Looking for an interventional cardiologist in Chennai? Worry not! Our cardiologist at Dr. Karthigesan Clinic provides expert guidance tailored to your specific heart health needs — whether you're interpreting smartwatch alerts or managing existing conditions.
Reach out to us today for professional cardiac care that goes beyond what any wearable can offer!
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Dr. Karthigesan
Dr Karthigesan A.M is an Electrophysiologist in Chennai, and a Senior Consultant Cardiologist, practising at the renowned Apollo Hospital in Chennai. He also conducts frequent consultations at Apollo's branches in Madurai, Trichy, and Guwahati. He holds an international certification in Cardiac Electrophysiology, making him an expert in his field. Read More
