Planks are a great way to tighten and strengthen the core. They can be done anywhere, anytime and require no equipment or special space. No excuses. Here is a 10 min plank circuit I did the other day as my ab work.
Do each of these positions back to back without rest. I did this pattern for 10 minutes straight ending on a regular plank. Adjust as necessary. Reduce or increase times. Add in short breaks if necessary. But ultimately work to do 10 minutes straight.
A. Regular Plank: 60 secs
B. Side Plank Right: 60 secs
C. Side Plank Left: 60 secs
-Wittig, ISSA CPT