Linnea Quigley's Horror Workout (1990)

After a nice shower, Linnea does some warm-up stretches and then goes for a run. She encounters some flabby zombies who follow her back to the house, where she leads them in some poolside aerobic routines. Later she unwinds by inviting some girlfriends over for a slumber party and some exercise. When something goes bump in the house, her friends begin experiencing an attrition problem.