New Indices of Arterial Stiffness Measured with an Upper-Arm Oscillometric Device in Long-Term Japanese Shigin Practitioners: A Cross-Sectional Exploratory Study

Background/Objectives: Arterial stiffness is an independent cardiovascular risk factor, and arterial velocity pulse index (AVI) and arterial pressure–volume index (API) are practical oscillometric markers. Shigin, a traditional Japanese vocal recitation practice characterised by abdominal breathing, has limited physiological evidence. This cross-sectional exploratory study examined the association between long-term shigin practice and arterial stiffness in older adults. Methods: Community-dwelling adults aged ≥60 years were classified into shigin practitioners (≥10 years), physically active non-practitioners, and inactive non-practitioners. AVI and API were measured using an upper-arm oscillometric device. Blood pressure, heart rate, salivary α-amylase (morning, standardised conditions), and peak expiratory flow were assessed. Results: Both shigin practitioners and active non-practitioners showed lower AVI and API, lower blood pressure, higher peak expiratory flow, and lower salivary α-amylase than inactive non-practitioners (p < 0.01). These associations remained significant after adjustment for blood pressure, heart rate, and sex. Conclusions: Long-term shigin practice was associated with arterial stiffness indices comparable to those of physically active older adults, without implying causality.