Normal results of CMCT to upper extremities do not correlate with height, age, or sex. In cases of peripheral conduction slowing, upper limits of CMCT must be adapted. Cervical root excitation can be carried out by electrical or magnetic stimulation. The F wave technique also produces reliable results. Electrical stimulation of lumbar roots produces the most reliable results when measuring CMCT to leg muscles. CMCT to the tibialis anterior correlates with height, but not with age or sex. The same is true for intraspinal motor conduction time. Contraction of the target muscle enlarges CMAP amplitudes after cervical and transcranial stimulation. However, a latency shortening is only seen after brain stimulation. This is thought to be at least partially due to spatial summation of D and I waves. Age affects peripheral nerve conduction and central nerve conduction in different ways.