A comprehensive review by Stanford University researchers has found that popular fitness wearables overestimate calorie burn by an average of 27 percent and underreport heart rate variability during high-intensity exercise.
The study tested 12 leading devices across 500 participants and found significant discrepancies between wearable readings and clinical-grade measurements. Accuracy varied widely between brands, with some performing within 5 percent of lab standards while others deviated by more than 40 percent.
Experts are calling for industry-wide accuracy standards and third-party certification programs to help consumers identify reliable devices for health monitoring purposes.
