Normal Hoffmann reflex latencies (H-M interval) in relation to age and body length.

The effects of age and body length on the Hoffmann reflex (H-M interval) was evaluated. 179 normal subjects (15-75 y, 150-200 cm) were tested. The normal upper limit (M + 2SD) of the H-M interval ranges from 22.0 ms (male, 155 cm, 20 y) to 34.3 ms (female, 195 cm, 70 y). The limit of 28 ms, that is often mentioned, holds only for young adults with a body length of less than 175 cm. Moreover it proved that a normal limit of the H-M interval asymmetry of less than 2 ms is too strict. For a mixed population less than 3 ms seems to be a safer upper limit for normal asymmetries.