PHYSIOLOGY OF AGING

对生理系统年龄变化的研究包括肾脏， 心血管和新陈代谢区域。肾小球滤过 24小时内生肌酐清除率与 通过静息或运动心脏运动来估计心脏功能 输出。因此，肾功能的年龄差异不可能是 在其他系统中既不被视为年龄变化的标志，也不被认为是年龄变化的标志 这是心血管系统的主要变化的结果。 通过在葡萄糖上的表现来评估葡萄糖代谢 耐受性测试与评估的认知表现无关 无论是通过记忆力测试还是解决问题时，年龄，教育， 肥胖或疾病也被考虑在内。 横截面和纵向分析表明，握力 在40岁以后以加速的速度下降。然而，抓地力 相当大比例的个体的力量不会减弱， 即使在年长的受试者中也是如此。随着年龄的增长，握力 力量的衰退比年龄相关的人预测的更严重 肌肉质量下降。

Studies of age changes in physiologic systems have included renal, cardiovascular, and metabolic areas. Renal glomerular filtration rate as estimated by 24 hr creatinine clearance was not related to cardiac performance as estimated by resting or exercise cardiac output. Thus the age differences in renal function cannot be considered either as a marker for age changes in other systems nor as a result of primary changes in the cardiovascular system. Glucose metabolism as assessed by performance on a glucose tolerance test was not related to cognitive performance as assessed either by tests of memory or problem solving when age, education, obesity or disease were taken into account. Cross-sectional and longitudinal analyses agree that grip strength declines at an accelerating rate after age 40. However, the grip strength of a sizable proportion of individuals does not decrease, and this is true even in aged subjects. With advancing age, grip strength deteriorates more than is predicted by the age-related decline in muscle mass.