Association between muscular strength and intrarenal vascular resistance in middle-aged and older individuals

A strategy for the preservation of intrarenal vasculature conditions remains obscure in middle-aged and older individuals without the renal disease. In the present study, we sought to identify whether the maintenance of muscular strength is an effective method of preserving the intrarenal vasculature condition of middle-aged and older individuals. Therefore, we applied a cross-sectional approach for investigating the relationship between muscular strength and the condition of the intrarenal vasculature. In 169 middle-aged and older individuals without renal disease, handgrip strength (HGS) and the renal resistive index (RRI) were measured as the parameters of muscular strength and intrarenal vascular resistance, respectively. The RRI was elevated with aging (r_s=0.499, P<0.001) and was inversely correlated with HGS (r_s=-0.370, P<0.001). The relationship between RRI and HGS remained significant after the consideration of confounders, including age and various central hemodynamic parameters. Furthermore, when the individuals were divided into four groups according to age (middle-aged or older) and the median HGS values, the RRI exhibited the highest values in the older group with lower HGS values (P<0.001). Our findings indicate that muscular strength as assessed by HGS is independently associated with the RRI (i.e. intrarenal vascular resistance) in middle-aged and older individuals. This finding suggests that the muscular strength may be one of the key factors to preserve the intrarenal vasculature condition.