Very little data exists regarding the cross-sectional area of the abdominals whereby the oblique muscles and transverse
abdominis appear to be too large to measure via ultrasound.
Therefore, the transverse
abdominis appears to be more heavily pennated in the lower abdomen, the internal oblique displays the opposite trend, and the external oblique is similarly pennated in both regions.
Not exact matches
Therefore, it
appears that the standing barbell overhead press produces higher levels of rectus
abdominis muscle activity than the squat or deadlift exercises.
The rectus
abdominis and external oblique
appear to display high levels of muscle activity during vertical pressing and pulling.
Using an unstable surface does not
appear to affect transverse
abdominis muscle activity during squats.
Additionally, the abdominal muscles
appear to vary in their morphology across the abdomen Rankin et al. (2006) reported that the rectus
abdominis and transverse
abdominis were larger when measured just below the rib cage, while the internal and external oblique were larger when measured at the mid point between the superior iliac crest and rig cage.
Overall, performing the bench press under unstable conditions
appears to produce superior rectus
abdominis muscle activity.
Rectus
abdominis muscle activity is higher in the standing horizontal press compared to the barbell bench press, while performing the seated overhead press and bench press on unstable surfaces do not
appear to be beneficial.
Nonetheless, it
appears that isometric core exercises such as the plank, as well as dynamic abdominal exercises such as the straight - leg sit up, produce greater rectus
abdominis muscle activity than many upper body and lower body compound exercises.