We have recently shown, using transcranial magnetic stimulation (TMS) to assess voluntary activation (VA), that neural drive to back muscles is reduced in subjects with chronic low back pain. There is also evidence that central nervous system drive to abdominal muscles is altered in these subjects, however VA has not yet been assessed for these muscles in healthy subjects; this is the purpose of the present study. Twenty one healthy subjects (10M:11F) participated. Electromyographic activity was recorded from back and abdominal muscles and flexor torque was measured using a dynamometer. Subjects performed a series of isometric voluntary contractions (10%–100% MVC) of rectus abdominis during which TMS was applied to the motor cortex. The resulting superimposed twitches (SIT) were measured and VA was derived.Background:
Methods:
