JMIR Publications

ABSTRACT

Background:

Smartwatches have gained prominence for their potential to offer accurate measurements of various physiological parameters. However, the validity of EE across different smartwatches models remains a topic of ongoing investigation. The discrepancy of results between models and gold standard equipment’s is particularly critical in the context of varying exercise intensities and types, as validation studies have demonstrated overestimation results when comparing wearable monitors with indirect calorimetry.

Objective:

To investigate the accuracy of two versions of Samsung smartwatch (Galaxy Watch 6 and 7) in measuring energy expenditure (EE) during exercise, using gold-standard methods as a reference (indirect calorimetry), during an intermittent moderate intensity running exercise.

Methods:

This study included 148 healthy adults composed of 80 men and 68 women. Participants performed intermittent running on a treadmill (walking at 5 km∙h for 1 minute and running between 8 and 16 km∙h for 2 minutes, based on the participant preference, with a total of 27 minutes). GW6 and GW7 models of Galaxy Watch were used. Energy expenditure was measured by indirect calorimetry (Cosmed K5) as a gold standard method.

Results:

No statistically significant differences were found between GW models and K5. K5 showed a mean EE of 213.60 ± 43.04, compared to GW6: 219.53 ± 35.70, and GW7: 202.67 ± 47.42 kcal (all p >0.05). Good Spearman correlations (0.63–0.70) and ICCs (0.65–0.74) were found. MAPE values ranged from 10.10% to 12.55%. Bland–Altman analysis revealed limits of agreement for all comparisons (K5 vs. GW6 and 7: −61.93 to 65.80 kcal).

Conclusions:

The GW6 and GW7 devices were valid for estimating energy expenditure during intermittent running exercises, demonstrating its suitability as a low-cost and practical wearable option for daily physical activities. Clinical Trial: The study protocol was approved by the Investiga - Institutos de Pesquisa ethics committee (CAE 62031722.4.0000.5599), and the entire study followed strict security, data collection and control protocols, respecting all technical precepts in all phases of its execution.