Killer Workout, also known under the original title Aerobicide, is a 1986 American slasher film written and directed by David A. Prior. It stars Marcia Karr, David James Campbell, Fritz Matthews, Ted Prior, and Teresa Van der Woude. The story revolves around a Los Angeles fitness club owned by Rhonda Johnson, whose twin sister Valerie was burned in a tanning salon two years ago. Detective Morgan begins to investigate the gym, after several of its members are brutally murdered by an unknown attacker.