The best replacement for leg curl is glute ham raise.

The best alternatives to leg curl are rated as following:
★★★★★  glute ham raise
★★★★★  seated leg curl
★★★★  leg extension
★★★  leg press
★★  romanian deadlift
★  stiff leg deadlift
★  sldl
★  rdl
★  seated
★  lying leg curl
  prone leg curl
  stiff legged deadlift

Your alternative for leg curl is not listed? Suggest!
Speaking about leg curl, one probably shouldn't forget about hip extension.

Other search terms related to leg curl and their ratings are:
★★★★★ hip extension
You have in mind a companion for leg curl and it is not yet here? Propose!



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leg curl
glute ham raise
seated leg curl