Association between physiological factors and grip and leg extension strength for predicting health outcomes: Tohoku Medical Megabank Community-based cohort study

Abstract

Background Upper and lower extremity muscle strengths predict health outcomes. However, the difference between each muscle's strength in physiological factors affecting the causal association is unclear. We aimed to evaluate the association between physiological data and muscle strength, measured using the grip and leg extension strengths, among Japanese adults. Methods We conducted a cross-sectional study of 2,861 men and 6,717 women aged ≥ 20 years, who lived in Miyagi Prefecture, Japan. The grip strength was measured using a dynamometer. The leg extension strength was measured using a hydraulic isokinetic leg press machine. Anthropometry and physiological data were assessed, including blood pressure, calcaneal ultrasound bone status, pulmonary function, carotid echography, and blood information. We used a general linear model adjusted for age, body composition, and smoking status to evaluate the association between muscle strength and physiological factors. Results Both grip and leg extension strengths were positively associated with the bone area ratio, vital capacity, forced vital capacity, forced expiratory volume in one second and eGFR, and negatively associated with the waist circumference and percentage body fat mass in both sexes. The diastolic blood pressure was positively associated with grip strength in both sexes and leg extension strength in men but not with leg extension strength in women. HDL cholesterol and red blood cell counts were positively associated with grip strength and leg extension strength in women, but not in men. In both sexes, the pulse rate, total cholesterol, and uric acid were consistently associated with only leg extension strength but not grip strength. In women, glycated hemoglobin demonstrated negative and positive associations with the grip and leg extension strengths, respectively. Conclusions The grip strength and leg extension strength demonstrated similar associations with anthropometry, pulmonary function, and eGFR, but the associations with the other factors were not always consistent. The impact of muscle strength on physiological data may partially follow different paths for the grip and leg extension strengths. Trial Registration Not applicable