The perma soundtrack at Mainframe Fitness, 3151 W. 111th St.: Dreamgirls. That’s because the personal trainer there, Lafonza Alston, slimmed down Jennifer Hudson, the Oscar-winning Chicago actress who starred in the film. Alston’s trick? His signature workout routine, the Trilogy of Terror.

I gave the workout a shot to see if I could handle it. After 20 minutes of cardio to warm up, we started the Trilogy: 25 squats, 25 crunches, and 25 pushups, followed by a one-minute break. Then again, and again, for a total of four sets. Around my 15th pushup in the first set, Hudson got to that song where she belts out, “And I’m telling you, I’m not going,” and Alston started singing along in falsetto. When I couldn’t do any more pushups, he let me do “the girl version,” with knees on the floor.

Alston, 44, designed the Trilogy for people on the move, for people who like to work out at home—and for people who, like Hudson, go on tour. The results? Only sore arms for me. But that’s not to say it doesn’t work. Check out Hudson’s hourglass.