Artificial intelligence (AI) and machine learning (ML) have become pivotal in advancing healthcare, enabling effective patient monitoring, activity tracking, vital sign analysis, and disease diagnosis through wearable devices. Recent advancements in medical sensor technologies have fueled significant growth in AI-powered applications for wearables over the past five years. This study examines the integration of ML into wearable devices for remote healthcare, offering a comprehensive overview of data flows and interactions. It highlights key challenges and uncovers potential opportunities to enhance the efficacy and adoption of these technologies in healthcare.