Against the backdrop of the overlapping national strategies of Active Aging and Digital China, fitness apps have become a core digital carrier for promoting health management among the elderly. However, the adoption and continuous usage rates of such products among this group remain persistently low. Most existing research on technology acceptance and health behaviors is rooted in the Western individualistic cultural context, analyzing user behavior from an individual-centric perspective, and largely neglects the profound impact of intergenerational family relations in China on the elderly’s technology usage behaviors. Based on the local Chinese context, this paper focuses on the specific needs of older adults in using fitness apps, clarifies the explanatory boundaries and application limitations of existing mainstream theories, identifies the core mismatches between the real needs of elderly users and the logical underpinnings of existing theories and product design, and finally proposes targeted optimization paths. This study aims to provide localized references for the age-friendly design and operation of fitness apps.