Immediate effects of Thai foot massage on renal blood flow, psychological stress, and heart rate variability in community-dwelling older adults: a randomized controlled trial

Background Renal blood flow (RBF) is regulated by an autonomic nervous system and is reduced in older adults. Massage has been previously found to increase blood flow. Objective This two-armed double-blind, randomized controlled trial aimed to investigate the immediate effects of Thai foot massage (TFM) on RBF, psychological stress, and heart rate variability (HRV) in older adult persons. Material and Methods The 26 healthy older adult volunteers were recruited and randomly assigned to the TFM group (13 persons) and the control group (13 persons). The TFM group received a 15-minute Thai foot massage, and the control group received a 15-minute bed rest. Primary outcomes – RBF parameters [peak systolic velocity (PSV), end-diastolic velocity (EDV), resistive index (RI), volumetric arterial blood flow (VF)] and secondary outcomes – HRV parameters [standard deviation of the normal-to-normal intervals (SDNN), root mean square of successive differences (RMSSD), high frequency (HF), low frequency (LF), and low frequency per high frequency (LF/HF)] were measured after each intervention. Results Results showed that the VF significantly increased after TFM (P < 0.05) but not in control. Meanwhile, the stress index significantly reduced after TFM (P < 0.05). SDNN and RMSSD, the proxies of parasympathetic activity, also significantly increased in the TFM group (p < 0.05). Only RMSSD was significantly enhanced in the control group. No side effects were observed. Conclusion The TFM could increase RBF and alleviate psychological stress through parasympathetic activity actuation. Therefore, this intervention might improve RBF and relieve stress in the older population. Further study should be carried out on a larger population.