If we were to do a poll and ask men what the hardest body part to train is, we're confident most would say their lower abs.

There are two reasons for that. First, you'll need to burn off belly fat—and belly fat is typically the most stubborn of all.

Second, you'll need to sculpt the tough-to-reach section of your rectus abdominus. Technically, your abs are all one muscle, but with the right targeted workout, you can hit the tough-to-train lower section.

This is that workout. Below are four moves that polish off your six-pack. Take 30 seconds of rest between exercises and repeat for two to three sets.