Maximum isometric trunk muscle strength and activity at trunk axial rotation during sitting

Anisotropy of human linea alba: A biomechanical study

“…However, electromyographic observations clearly demonstrated the transversus muscle to be most significant in intraabdominal pressure production [18,22] and to be recruited preferentially in breathing [19]. In contrast, the internal and external oblique muscles are more effective in contributing to trunk movements [23,24] and stabilization of the spine [25]. The linea alba has to be seen as the decussation of the tendon fibers of the abdominal wall muscles.…”

Isometric axial rotation of the human trunk from pre-rotated postures

“…They measured the torque generated with 30°pre-rotation in and against the rotation direction. Tore´n and Ö berg (1999) measured the electromyogram (EMG) and torque with 20°a nd 40°pre-rotation in both directions. Also, they measured the EMG bilaterally from the erector spinae, external oblique, internal oblique and rectus abdominis at the L 3 level.…”

“…With increased asymmetry to 30°, the torque declined by 25% to 33% in the direction of pre-rotation and increased between 21% and 31% in the opposite direction. Tore´n and Ö berg (1999) measured the torque and EMG of external obliques, rectus abdominis and erector spinae with 20°and 40°pre-rotation in either direction, in addition to the neutral posture. They also reported that the subjects could exert greatest torque when being pre-rotated in the opposite direction and the lowest torques when being pre-rotated in the same direction as the direction of exertion.…”

“…They also found a bilateral asymmetry between right and left rectus abdominis and internal obliques with pre-rotation of the trunk. Tore´n and Ö berg (1999) reported a significant difference in external oblique deployment between two groups of their subjects -tractor drivers and office workers -which were assigned to work conditioning. Based on their observation of increased torque with prerotation opposite to the direction of the rotary effort, Pope et al (1987) recommended such pre-rotation in occupational activity.…”