SUMMARY / ABSTRACT: Atherosclerotic peripheral arterial disease (PAD) of the lower extremity affects over 8.5 million Americans, including 25% of individuals over 80 years of age, and is typified by debilitating leg pain when walking. Untreated, progressive disease results in unrelenting rest pain, ulcers and limb loss.1 Treatment options are limited as revascularization procedures are both expensive and associated with considerable morbidity and mortality whereas pharmacologic therapy is only marginally effective. Supervised exercise therapy, however, is a cost-effective, minimally invasive technique that has proven to be as effective as revascularization for alleviating most common PAD symptoms. Supervised exercise therapy sessions for claudication remain difficult for older adults because of pain during treatment, indirect costs, geographic constraints, pandemic concerns, and concomitant caregiver roles. Infrared Rx, Inc proposes to design and develop novel technology to complement or replace supervised exercise rehabilitation for older adults with PAD. This technology uses near infrared spectroscopy (NIRS) to measure limb hypoxia in real time and thus provide high fidelity, actionable information that allows patients to tailor their own exercise session based on visual or haptic user interfaces – fostering increased adherence to both supervised and self-directed training sessions. As the onset of hypoxia precedes claudication pain, NIRS affords a potential surrogate for tissue ischemia during walking that can be used to direct exercise intensity. We have demonstrated in a small, randomized clinical trial funded by the American Heart Association that a NIRS guided exercise program can effectively improve 6-minute walk times in patients with PAD, but without the debilitating pain of a traditional supervised exercise program.6 This non-invasive, innovative technology has the potential to solve specific challenges that limit the efficacy of supervised exercise therapy for aging adults with PAD; its current form, however, still requires an onsite technician for monitoring during training. Our central hypothesis is that NIRS-guided exercise programs can improve compliance with exercise prescriptions, decrease morbidity, and improve independence in older Americans with PAD. The following proposal will establish the foundation upon which we can develop a commercially viable software analysis platform that allows older adults to engage in exercise with 1) minimal pain and 2) on a self- directed basis. Successful development of this technology requires: 1) identification of the technical parameters needed to reliably make accurate NIRS measurements in older Americans with PAD; 2) automation of data-collection and analysis.