Textile-based sensors are being integrated into garments for the monitoring of physiological signals from the human body. Commonly, textile sensors are implemented through knitting methods, while the response of these sensors from other structures has been less studied. This work analyzed the feasibility of using a textile-based stretch sensor with a coverstitch formation integrated into a commercial shirt for monitoring breathing patterns. For comparison, a Respiratory Inductive Plethysmograph (RIP) based breathing system was used. Data from three subjects performing eight different activities were collected in a controlled environment. The performance of the textile sensor was evaluated based on the mean absolute error breathing rate captured using different segment sizes and as the degree of correlation to the RIP sensor. Results showed an average breathing rate error of 0.97+0.42 breaths/epoch for an epoch size of 10s. The average correlation with the RIP sensor signals was p=0.41+0.2. Results suggest that this garment-integrated sensor could be potentially used in the monitoring of breathing rate.