Maintaining the half sit-up position while performing any movement with the arms will challenge the abs, hip flexors, and even the neck musculature.
Anchor your feet under something stable and lean back until you feel your abs turn on. Try to keep your spine and neck as neutral as possible. You can go light and do the exercise for 60 seconds, or use heavier weights and shoot for 10-15 reps.
Hello, T-Nation peckerheads! I'm the Critic. My job in this new article series is to call out various T-Nation contributors and put them on the firing line.