Regional differences in abdominal muscle activity during various maneuvers in humans

Abstract

To determine if regional differences exist in the activity of abdominal muscles during respiratory and nonrespiratory maneuvers, we studied four healthy subjects by comparing electromyographic (EMG) activity from surface electrodes placed lateral to rectus muscle, one pair on the upper abdomen and the other on the lower abdomen. In one subject EMG recordings were made from wires placed in various layers of the abdominal wall. Relative positions and changes in size of anatomic structures during maneuvers were determined from real-time ultrasonography of the abdominal wall. Expulsive or valsalva maneuvers evoked the same relative EMG activity in the upper and lower abdomen. In the resting supine posture no EMG activity was detectable; however, in the standing posture greater tonic EMG activity appeared in the lower abdomen. During rebreathing, phasic EMG activity during expiration was greater in the upper than in the lower abdomen in all subjects. Observations from ultrasonographic and electromyographic evaluations suggest that the control of abdominal muscles and their influence on respiratory mechanics are potentially more complex than has been suggested by previous reports.

Capsaicin exposure elicits complex airway defensive motor patterns in normal humans in a concentration-dependent manner

“…In support of this view, we report a comparable increase in airflow and abdominal muscle activity to increasing capsaicin concentration. Similar observations were made in previous studies [25,29]. Furthermore, the coordinated relationship between airflow and abdominal muscle activity is preserved in some disease states and with age.…”

“…In cats, the RA plays a major role in the expulsive phase [7,24], whereas in humans the EO is thought to be the major abdominal muscle [18,19,25]. We did not compare the degree of activation of the IC8, EO or RA, but we do show that the relative increase in activation of these muscle groups was the same with increasing capsaicin concentration.…”

An electromyographic method of objectively assessing cough intensity and use of the method to assess effects of codeine on the dose‐response curve to citric acid.

“…The driving force of the cough mechanism is the contraction of the abdominal muscles and in particular the lateral abdominal muscles (Floyd & Silver, 1950;Strohl et al, 1981 suggest that use of such an integrated EMG may provide a useful objective measure of cough intensity. This measure can also be used to assess cough threshold to citric acid challenge.…”

What is cough and what should be measured?

“…The expiratory muscles of the ventrolateral aspect of the abdominal wall are intensely activated during both the compressive and expulsive phases of cough [28] and the ER [8,12]. The chief expiratory muscles are the internal intercostals, the oblique (external and internal) muscle, the tranversus abdominis, and the rectus abdominis [see 29].…”