De Troyer A
Respir Physiol. 1983 Sep;53(3):341-53. doi: 10.1016/0034-5687(83)90124-x.
Abdominal muscle activity was studied in 10 normal naive subjects during quiet breathing in different body positions. Electromyograms of the upper and lower portions of the external oblique and rectus abdominis were recorded with bipolar needle electrodes and changes in abdominal and rib cage displacements were measured using linearized magnetometers. The abdominal muscles were always silent in the supine posture. In contrast, 8 of the 10 subjects showed tonic abdominal muscle activity in the standing posture and 4 of the subjects did so also in the 45 degrees head-down position; when present, this activity was always greater in the dependent (where the hydrostatic pressure was greater) than in the non-dependent portion of the muscles. Tonic abdominal muscle activity was associated with a reduction of abdominal volume throughout the respiratory cycle and a reduction of the end-expiratory lung volume below the neutral position of the respiratory system. We conclude that (1) tonic activity is present in the abdominal muscles in most standing subjects, (2) this activity is primarily related to the magnitude of hydraulic pressure exerted by the abdominal contents on the abdominal wall, and (3) in most normal individuals standing at rest, the end-expiratory position is at least in part actively determined. Such an abdominal muscle use, although causing quiet breathing to depart from the relaxed abdominothoracic configuration, may be associated with minimum respiratory work.
在10名正常的未受过训练的受试者处于不同体位安静呼吸时，对其腹部肌肉活动进行了研究。使用双极针电极记录腹外斜肌和腹直肌上下部分的肌电图，并使用线性化磁力计测量腹部和胸廓位移的变化。在仰卧位时，腹部肌肉始终处于静息状态。相比之下，10名受试者中有8名在站立位时表现出腹部肌肉的紧张性活动，4名受试者在头低45度位时也表现出这种活动；当存在这种活动时，在依赖侧（此处静水压力更大）的肌肉活动总是比非依赖侧更大。腹部肌肉的紧张性活动与整个呼吸周期中腹部容积的减少以及呼气末肺容积低于呼吸系统中性位置有关。我们得出结论：（1）大多数站立的受试者腹部肌肉存在紧张性活动；（2）这种活动主要与腹部内容物对腹壁施加的液压大小有关；（3）在大多数静息站立的正常个体中，呼气末位置至少部分是由主动因素决定的。这种腹部肌肉的使用方式，尽管会使安静呼吸偏离放松的腹胸构型，但可能与最小的呼吸功相关。
