The best replacement for plank is crunches.

The best alternatives to plank are rated as following:
★★★★★  crunches
★★★★★  vinyl siding
★★★★★  laminate flooring
★★★★  bridge
★★★  sit up
★★★  push up
★★★  laminate
★★  crunch
★★  board
★★  docky
★★  hover
★★  cairo dock
★  forearm plank
★  planche
★  dolphin plank
★  bridge exercise
★  strip hardwood
★  raised plank
★  pushups
★  take your panties off
★  cedar
★  elbow plank
★  sideways plank
  low plank
  modified plank
  ab wheel
  strip
  dundee plank
  push ups
  siding

Your alternative for plank is not listed? Suggest!
Speaking about plank, one probably shouldn't forget about our eyes wide open.

Other search terms related to plank and their ratings are:
★★★★★ our eyes wide open
You have in mind a companion for plank and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of plank in all years. Click on graph for more.
plank
crunches
vinyl siding