Neck builder

I did an exercise video a few days ago, called "core builder". This resulted in my abdominal area being sore: front, left side, right side. Which I expected. What surprised me was that my neck was also sore.

Now, I'd like to have stronger muscles. It enables me to do a wider variety of yoga postures. It lets me safely lift heavier parts at work. I have a few aerobic workout tapes I can't do safely (i.e. they make my back hurt) if I don't have some strength trained before doing them.

However, I don't need a thick, sinewy neck for any of those activities. It makes me wonder if, when they put that workout together, the choreographers completely thought things through.