"Ask the Coach" is the column in which Wolfgang Unsöld answers your questions. The book of the same name is available right here on Amazon.
Question: I read in your book The Perfect Squat that you use the barbell ab rollouts, but don't increase the resistance with bands like you often see. Why don't you increase the resistance? Patrick L
WU: The reason I don't use resistance in the form of bands or even larger discs on LH ab rollouts is simple: This resistance doesn't increase abdominal recruitment. In detail, it is crucial to look at "the line of pull" or "the direction of resistance". The main task of the abdominal muscles, the primarily trained muscles of the LH ab rollouts, is their anti-extension function, i.e. they prevent the lumbar spine from sagging and thus train the stabilization of the spine to maintain its natural S-curve. Especially at the lowest point where the spine is horizontal and therefore most of the work is done by the abdominal muscles in relation to the force of gravity. This means that the more horizontal the spine, the higher the recruitment and thus the training effect on the abdominal muscles. In order to increase - or possibly decrease - the recruitment of the abdominal muscles, the vertical force of gravity would have to be increased - or possibly decreased. Most exercises increase vertical forces primarily with barbells, dumbbells, weight stacks, or plates, such as squats with a barbell on your back or pull-ups with plates in a belt.
However, if I increase the resistance in the form of bands or even larger disks in LH Ab rollouts, I do not increase the vertical forces but the horizontal forces. This does not increase the recruitment of the abdominal muscles responsible for controlling and stabilizing horizontal forces. The control and stabilization of the horizontal forces occurs primarily via the latissimus , which is responsible for shoulder extension and thus brings the arm from the overhead position at the turning point of the LH ab rollout back towards the vertical. However, an increase in lat recruitment is uninteresting in LH Ab rollouts, since the lat recruitment increases over a very small radius. It's about 30° to 40° compared to an overload of 160° to 190° on pull-ups and a correspondingly significantly higher total muscle recruitment in relation to the radius and resistance used.
In a nutshell, the primary muscles worked in LH Ab Rollouts are the abdominal muscles. An increase in recruitment requires an increase in vertical forces. Ligaments and larger discs (which also decrease range of motion) do not increase these vertical forces. And as such, are not a viable option for increasing abdominal recruitment in LH Ab rollouts.
One exercise variant of the LH ab rollout that increases the duration of the vertical forces, and therefore abdominal muscle recruitment, during LH ab rollouts is paused LH ab rollouts with a 2- to 6-second pause in the bottom position.
As explained in the book, my primary progression on the LH Ab rollouts is increasing the volume to 25 reps. In combination with a break in the lowest position. So as to maximize abdominal muscle recruitment.
Good LH Ab rollout progression!
Image: An excerpt from the "The Perfect Squat" book on the LH Ab Rollouts.