The Effect of Tattoos on Heart Rate Validity in the Polar Verity Sense Commercial Wearable Device

This study evaluated the accuracy of heart rate (HR) measures of a commercial wearable device on tattooed skin and assessed tattoo characteristics associated with HR accuracy. Participants (<i>n</i> = 25) wore a chest strap HR monitor (criterion) and an armband HR monitor (experimental) during rest and self-paced walking and running. Conditions with the experimental device on tattooed and non-tattooed sections of skin were completed, and HR was collected every second and compared via Lin's correlation (CCC) and the mean absolute percent error (MAPE). Skin tone and tattoo age and intensity were evaluated with HR accuracy. HR from tattooed skin was not accurate during rest (MAPE = 22.9%; CCC = 0.25), walking (MAPE = 7.5%; CCC = 0.68), or running (MAPE = 5.1%; CCC = 0.83). Measures taken on non-tattooed skin were within acceptable standards for accuracy throughout all three conditions (MAPE < 5%; CCC > 0.90). Skin tone was the only characteristic found to contribute to HR accuracy during rest (<i>p</i> = 0.046) and walking (<i>p</i> = 0.045). No variables loaded for running. The presence of arm tattoos affected HR readings, with the greatest inaccuracy occurring at rest. Specific tattoo characteristics did not statistically contribute to HR accuracy, as shown by the regression analysis. More research is needed to clarify how the varied tattoo characteristics affect HR devices.