After a Year of Using Fitness Trackers, She Started Questioning Her Own Judgment
Recently, Indian actress Ankita Konwar shared her honest experience after using a fitness tracker for a year. She admitted that long-term reliance on device-generated sleep scores, heart rate data, and step counts gradually made her question her own bodily sensations and judgment. Her post resonated with many fitness enthusiasts: how much should we trust smartwatches and fitness bands?
What Can Smartwatches Monitor?
Mainstream fitness trackers typically offer the following features:
- Sleep monitoring: Estimates deep, light, and REM sleep duration using accelerometers and heart rate variability, generating a sleep score.
- Heart rate monitoring: Uses photoplethysmography (PPG) technology to measure heart rate in real time or at intervals; some devices can alert users to abnormal resting heart rates.
- Steps and calories: Tracks daily activity and estimates energy expenditure.
- Blood oxygen and stress: Some high-end devices can monitor blood oxygen saturation and stress levels.
Are the Data Reliable? What Are the Limitations?
Research shows that fitness trackers are relatively accurate for step counting, with errors typically within 5%. However, calorie expenditure estimates can have errors of 20%–40%. The accuracy of sleep staging algorithms is also often questioned, with notable deviations compared to professional polysomnography (PSG). Additionally, wrist placement, skin tone, and movement status can all affect heart rate measurement accuracy.
More importantly, device data reflects estimates based on population-level algorithms, not precise individual medical metrics. Over-focusing on sleep scores may even trigger "perfect sleep anxiety," making it harder to fall asleep the more you check the data.
How to Use Fitness Trackers Scientifically
- Look at trends, not single readings: Focus on weekly or monthly changes rather than one day's sleep score.
- Prioritize bodily sensations: If the device says "poor sleep" but you feel energetic, don't over-worry.
- Don't replace medical diagnosis: Abnormal heart rate or low blood oxygen data can be a reference for seeking medical care, but cannot replace professional examinations.
- Calibrate regularly and wear correctly: Ensure the device fits snugly on your wrist and is positioned correctly during exercise.
Conclusion
Fitness trackers are辅助 tools, not health judges. Learning to listen to your body while using device data as a reference is a more rational approach to health management. The Xiaoshu Health App can sync with Apple Health to track relevant metrics, helping you better understand your sleep, heart rate, and activity trends—so data truly serves your health.