부산대학교 도서관

This paper investigates the performances of a head-mounted wearable device for the breath-by-breath monitoring of respiratory frequency ( ${f}_{{R}}$ ) during exercise. The device exploits a new algorithm to estimate ${f}_{{R}}$ from the breathing-related pressure drops ( ${\Delta } {P}$ ) recorded at the nostrils level. Performances of the wearable device in measuring the breath-by-breath and 30-s average ${f}_{{R}}$ values were evaluated during two high-intensity cycling exercise tests performed in the laboratory. ${\Delta } {P}$ signals were collected from ten volunteers with the wearable device, and the simultaneous measurements with a reference instrument were performed for validation purposes. In addition, numerical simulations were carried out to reproduce the conditions expected in applied settings. Bland–Altman analysis, linear regression ( ${r}^{2}$ ), and percentage error (% $E$ ) were used for comparing the two instruments. Experimental tests demonstrate the robustness and validity of the proposed wearable device and the related algorithm to measure the breath-by-breath ${f}_{R}$ (overall $\%{E} = {4.03\%}$ ) and 30-s average ${f}_{R}$ (overall ${\%E} = {2.38\%}$ ) values. Biases obtained with the breath-by-breath analysis (max. −0.06 ± 6.27 breaths/min) were higher than those obtained in the 30-s window analysis (max. −0.03 ± 1.60 breaths/min). In the simulated conditions, $\%E$ increased up to 6.65%. The proposed wearable device is suitable for a wide variety of indoor applications where the ${f}_{R}$ monitoring during exercise at reduced invasiveness is of great value.