Co-activation of the abdominal and pelvic floor muscles during voluntary exercises

The response of the abdominal muscles to voluntary contraction of the pelvi c floor (PF) muscles was investigated in women with no history of symptoms of stress urinary incontinence to determine whether there is co-activation of the muscles surrounding the abdominal cavity during exercises for the PF muscles. Electromyographic (EMG) activity of each of the abdominal muscles was recorded with fine-wire electrodes in seven parous females. Subjects c ontracted the PF muscles maximally in three lumbar spine positions while ly ing supine. In all subjects. the EMG activity of the abdominal muscles was increased above the baseline level during contractions of the PF muscles in at least one of the spinal positions. The amplitude of the increase in EMG activity of obliquus externus abdominis was greatest when the spine was po sitioned in flexion and the increase in activity of transversus abdominis w as greater than that of rectus abdominis and obliquus externus abdominis wh en the spine was positioned in extension. In an additional pilot experiment . EMG recordings were made from the pubococcygeus and the abdominal muscles with fine-wire electrodes in two subjects during the performance of three different sub-maximal isometric abdominal muscle maneuvers. Both subjects s howed an increase in EMG activity of the pubococcygeus with each abdominal muscle contraction. The results of these experiments indicate that abdomina l muscle activity is a normal response to PF exercise in subjects with no s ymptoms of PF muscle dysfunction and provide preliminary evidence that spec ific abdominal exercises activate the PF muscles. Neurourol. Urodynam. 20:3 1-42, 2001. (C) 2001 Wiley-Liss, Inc.