Cardiovascular responses and the sense of effort during attempts to contract paralysed muscles: role of the spinal cord.

To determine whether spinal transection affects the cardiovascular response and the sense of effort which accompany attempts to contract paralysed muscles in normal subjects, paraplegic patients tried to contract paralysed leg muscles. During attempted contractions, paraplegic subjects reported a sense of effort but did not change heart rate or blood pressure. However, these subjects had a normal cardiovascular response to handgrip contractions. These data suggest that pathways descending to and arising from the spinal cord below the lesion are required to generate a cardiovascular response but are not necessary for the sense of effort.