Carel R S, Korczyn A D, Hochberg Y
Am J Med Sci. 1979 Jul-Aug;278(1):57-63. doi: 10.1097/00000441-197907000-00007.
Achilles tendon reflex time was measured in normal subjects (1,837 females and 7,937 males). Values of half relaxation time showed a clear dependency on both age and sex. The reflex becomes slower with advancing age and was consistently slower in females. The results redefine the normal range of the Achilles tendon reflex. Regression lines of relaxation time on age were fitted for each sex separately. Lines representing linear regression, log-linear regression or quadratic regression were inferior to those described by linear splines. The gradual increase of Achilles tendon relaxation time with age was not due to unrecognized hypothyroidism or peripheral neuropathy. It is suggested that one cause of the progressive increment is diminution of sympathetic tone with age, and changes in the muscles themselves may also contribute.
在正常受试者（1837名女性和7937名男性）中测量了跟腱反射时间。半放松时间值显示出对年龄和性别的明显依赖性。随着年龄的增长，反射会变慢，并且女性的反射始终较慢。这些结果重新定义了跟腱反射的正常范围。分别为每个性别拟合了放松时间与年龄的回归线。代表线性回归、对数线性回归或二次回归的线不如线性样条所描述的线。跟腱放松时间随年龄的逐渐增加并非由于未被识别的甲状腺功能减退或周围神经病变。有人提出，这种逐渐增加的一个原因是随着年龄增长交感神经张力降低，肌肉自身的变化也可能起作用。
