Validation of a Biometric Smart Shirt for Assessment of Physical Activity

Abstract

Smart shirts are embedded with sensors to collect physiologic data (e.g., heart rate and breathing rate/volume) and an accelerometer to assess kilocalories (kcals) and steps. However, little is known about measurement accuracy of smart shirts. PURPOSE: The purpose of this study was to validate a smart shirt for assessment of physiologic and physical activity variables. METHODS: Participants (n=32) aged 18-51 years wore a smart shirt and performed 15 total activities, 12 in the laboratory and 3 on a 200-m indoor track. Lab activities were performed for 5 min each and included lying, sitting, standing, walking at various speeds (2.0, 3.0, 3.5-4.0 miles*hr-1) and inclines (0%, 5%, 10%), jogging, and cycling. Track activities included self-paced walking (200 m, 2 speeds) and jogging (400 m). Steps, kcals, heart rate, and breathing rate and volume from the smart shirt were compared to criterion measures (metabolic analyzer for kcals and breathing rate/volume, pedometer for steps, and pulse oximeter for heart rate). Percent (%) errors were calculated between smart shirt estimates and criterion-measured variables. A threshold of 10% was used for low (≤10%) vs. high (>10%) predictive error. Paired samples T-tests were conducted to determine significant differences between smart shirt estimates and criterion measurements with p<0.05 used to denote statistical significance. RESULTS: Estimates made by the smart shirt had high % error (shown as mean [standard error]) for kcals (29.8% [3.1]), breathing rate (19.4% [4.3]), and breathing volume (33.6% [3.8]). The smart shirt had low % error for steps (9.4% [0.7]) and heart rate (2.7% [0.3]). For all activities, kcals and breathing rate and volume performed poorly (>10% error), whereas heart rate had <10% error for all activities. Step predictions were significantly underestimated for slow walking speeds (16.7-36.1%, p < 0.05), and kcals were significantly overestimated during all activities (5.6-94.7%, p < 0.05). CONCLUSIONS: The smart shirt performed well estimating and heart rate, but performed poorly estimating kcals, breathing rate and breathing volume. Future research should further examine accuracy of this smart shirt during sport-specific activities as well as in free-living protocols. This study was supported by the Alma College CORE Research Grant.