So, so many of us skip ab exercises. Especially as we get older. Because they seem to get more difficult rather than getting easier. But abandoning our core leads to far greater mobility and balance problems down the road. Review this link for a brief discussion on the importance of building our core and some valuable tips on how to do so.
Plank exercises engage the entire body core and trunk, not just our abs. And there are more than one static way to perform planks. Click the link here for a short article and a video demonstrating the plank variations.