Exploring Combing Techniques to Enhance Extracranial Blood Flow: A Randomized Controlled Trial

Objective: Combing, a common daily practice, may promote brain health by improving both extracranial and intracranial blood circulation, as demonstrated in stroke models. However, the optimal combing direction for maximizing circulatory benefits remains unclear. This study was to investigate how the combing direction affects extracranial circulation in healthy adults. Materials and Methods: In this open-label randomized controlled trial, a total of 62 healthy participants were assigned to two groups: Group F–B (front-to-back combing) and Group B–F (back-to-front combing). Participants combed their hair for 5 min using their dominant hand at a consistent frequency, ensuring uniform coverage of the scalp. Blood flow and skin temperature in the ear concha and auricle were measured before and after combing using laser speckle flow imaging and thermometry. Results: Both groups showed significant increases in scalp, ear, and hand skin temperatures. Group B–F exhibited a significant increase in ear blood flow ( P = 0.0027), whereas Group F–B showed no significant change ( P > 0.05). Conclusions: Back-to-front combing significantly enhanced extracranial blood flow, particularly in the ear, indicating that combing direction influenced circulatory outcomes. These findings support back-to-front combing as a simple approach to promoting head circulation within traditional Chinese medicine practices. Clinical trial registration: The study was approved by the Ethics Committee of Beijing University of Chinese Medicine (2020BZHYLL0108), and all participants provided written informed consent.