Get in the half-sit-up position with your feet anchored. Maintaining this half sit-up position while doing any movement with the arms will challenge the abs, and this one hits the delts as well.
Try to keep your spine and neck as neutral as possible. Go light and do the exercise for one continuous minute, or go a bit heavier and aim for 10-15 reps.
This new Q & A column is about building a muscular and aesthetic physique. It's not about breaking strength records or reaching speed and power personal bests.
The Special Forces community has some of the toughest fighting men in the world, but the military's training methods are antiquated. And CrossFit isn't the answer.