Kidney Blood Flow During Exercise in Older African American Adults

The goal of this preliminary study is to learn if healthy older African American (AA) adults have a larger change in their kidney blood flow during exercise compared to White (W) adults. The main questions that this study aims to answer are: * Do healthy older AA adults have a larger decrease in kidney blood flow during exercise compared to W adults? * Do healthy older AA adults have a larger decrease in kidney blood flow during other types of stress compared to W adults? During one visit in the research lab, participants will: * Perform cycling exercise while lying down * Undergo a cold hand test * Perform a mental math test Completing this preliminary study will help researchers to understand more about why many AA adults have heart and kidney problems, so future research can study ways to reduce the number of AA adults who have these health issues.