Jillian Michaels' workout and upper back strength

Hi!

I have been working out to JM's Yoga Meltdown, No More Trouble Zones, six weeks Six Pack, Banish Fat Boost Metabolism. I just found that I have a bad posture because my upper back (traps, especially) lacks strength. Has anyone found the above fitness videos to work your upper body very little or may be not as much as other parts of your body?