Stress & Motivated Behavioral Institute (SMBI) has developed a research program to provide an objective evaluation of the physiological and neurocognitive impact of human electromuscular muscular interference (HEMI) devices in humans. The initial step is to understand their physiological impact, which is characterized by vital signs. Volunteers are recruited from HEMI training programs with the provision that data collection can not interfere with training. Thus, an ambulatory system was assembled. There are two main issues in the current ambulatory system, one of which is the reliability of the respiration signal obtained using a strain gauge respiration band, mainly due to motion artifact.The field of monitoring heart rate and respiratory rate using the photoplethysmograph (PPG) signal is rapidly growing. The main objectives of the thesis is to design a PPG hardware an ear clip sensor and analog processing circuit -- to comprise respiration related information and build a software using autoregressive modeling technique to extract respiratory rate from the PPG signal. The custom hardware and software verification results are compared with that of off-the-shelf Nonin® pulse oximetry module -- Xpod®. The custom hardware PPG signal was affected more significantly by motion artifact than the Xpod® hardware output. Discrepancies in detecting 6 breaths per minute using custom PPG signal were noted. In conclusion, a few changes in the custom hardware circuit are suggested to further improve the software results in an ambulatory setting. In addition, a more controlled study is suggested.