The Chinese cardiorespiratory and circulatory system at work in women and men: a case–control studyResearch in context

Summary: Background: The physiology of prominent prognostic factors in the cardiorespiratory system remains unchartered in the world's largest ethnic group: Hans Chinese (HC). This study assessed and contrasted the fundamental variables in HC and European-American (EA) individuals. Methods: Healthy HC and EA adults (n = 140, 43% ♀) closely matched by age, sex and physical activity were included. Body composition (DXA) and haematological variables (haemoglobin mass, blood volume (BV)) were measured at rest. Pulmonary O2 uptake (VO2) measurements along with cycle ergometry designed for accurate transthoracic echocardiography were implemented to assess cardiorespiratory structure/function up to peak effort. Findings: HC presented with higher body fat and lower lean body mass (LBM) percentage than EA irrespective of sex (P ≤ 0.014). BV did not differ whereas blood haemoglobin concentration was lower in HC compared with EA, particularly in females (P = 0.009). Myocardial diastolic and overall function at rest was enhanced in HC versus EA (P < 0.001). During exercise, heart volumes and output per unit of body size did not differ between ethnicities, whereas larger heart volumes per unit of LBM were found in HC versus EA in females (P ≤ 0.003). At high exercise intensities, VO2 (−16%) and the arteriovenous O2 difference (−28%) were markedly reduced in HC compared with EA in females (P ≤ 0.024). In males, no physiological difference between HC and EA was observed during exercise. Interpretation: Notwithstanding lower LBM, HC are characterised by similar BV and cardiac capacity but reduced peak VO2 than EA in females, partly explained by low ethnic-specific blood O2 carrying capacity. Funding: Early Career Scheme (106210224, to D.M.) and Seed Fund (104006024, to D.M.).