Project Summary It is predicted that 13.8 million US adults will live with Alzheimer’s disease (AD) by 2050. Physical activity (PA) is imperative to prevent or delay the onset of AD. However, adherence to the national PA guidelines steeply declines after ages 60-65. Fewer than 20% of US older adults adhere to the national guidelines for multicomponent PA - aerobic exercise (AE) at moderate intensity and strength training (ST). Thus, there is an urgent need to promote multicomponent PA among low-active older adults. A major challenge to promoting multicomponent PA is that most older adults experience a negative affective response to moderate-intensity AE and ST. This negative affective response is a critical barrier to maintenance of regular PA because, in general, people are unlikely to continue a behavior that results in immediate displeasure. Interestingly, listening to music during acute bouts of AE and ST increases positive affect and reduces perceived exertion. However, for these benefits to translate to long-term adherence, music alone is not sufficient. In a feasibility study (N=33), walking-for-exercise with a sonically enhanced music playlist in the form of Rhythmic Auditory Stimulation (RAS) – an application of pulsed, tempo-synchronous, auditory stimuli (e.g., beat-accented music) for the facilitation of rhythmic body movement – nearly doubled the weekly volume of PA and caloric expenditure in midlife-to-older patients undergoing cardiac rehabilitation whereas standard music without RAS had little effect on PA outcomes. To date, this proof-of-concept has not been fully tested and the underlying psychological mechanisms of RAS remain unknown. Thus, we propose to test whether RAS enhances affective responses to PA and thereby promotes long-term PA behaviors among older adults. In the R61 and R33 phases, participants will undergo an exercise intervention (EX) consisting of ST for 3 days/week and brisk walking for AE for >150 min/week over 6 months. The EX is designed to foster the independent maintenance of regular PA through a gradual withdrawal of supervised training (3 days/week for 2 months, 1 day/week for 2 months, and unsupervised for 2 months). The independent variable will be random assignment into the EX alone or EX+RAS. In the R61 phase, we will conduct an RCT to explore the preliminary effects of RAS on affective and behavioral responses to the EX among non-demented, low-active, older adults (N=40) aged 65- 79 (Aim 1). Using ecological momentary assessment (EMA), we will test the hypothesis that adding RAS to the EX leads to a more positive affective response to PA, lower perceived exertion, and greater weekly volumes of PA over 6 months. Treatment adherence and satisfaction will be assessed to determine the acceptability of the interventions. If milestones are met, we will proceed to the R33 phase and conduct a fully-powered RCT with the same design and population (N=130). We will retest Aim 1 with this second larger sample a...