The best replacement for cardio workout is fat burning.

The best alternatives to cardio workout are rated as following:
★★★★★  fat burning
★★★  fat burning workout
★★  fat burn workout
★★  fat burn
  my fitness coach

Your alternative for cardio workout is not listed? Suggest!
Speaking about cardio workout, one probably shouldn't forget about weights.

Other search terms related to cardio workout and their ratings are:

★★★★★ weights
You have in mind a companion for cardio workout and it is not yet here? Propose!

Google Trends

Scale is based on the average worldwide traffic of cardio workout in all years. Click on graph for more.
cardio workout
fat burning
fat burning workout