Toughest workouts in L.A.

This is Luke Milton, trainer and owner of Training Mate, the Australian circuit training class

Milton’s workout combines killer cardio -- and bad jokes.

The bad jokes supposedly take your mind off the pain. Supposedly.

Meet LIT Method co-founders Taylor Gainor, left, and Justin Norris.

The pair promises a grueling low-impact workout that will “build you up, not break you down.”

That means no running, jumping or weights, so less impact on bones and joints.

But it’s far from easy-does-it. The 50-minute challenge at LIT is filled with Tabata-style sprints on water rowers, coupled with total-body strength moves.

Sebastien Lagree developed the new Supra reformer machine at Lagree Fitness, which has a celebrity following.

Part mechanical bull, part next-generation Pilates reformer, the Supra takes traditional strength training up a notch.

Users struggle to stay on the machine through a series of tough combination exercises, all while an instructor uses an app to tilt the machine not only up and down but also left and right.

“You are always working your core,” Lagree says.

“By the end of the initial leg segment, I was out of breath and my thighs were shaking like Jell-o,” said our writers, who added: “A word of caution: There were a couple of times when my muscles were so fatigued that I thought I might fall off the machine.” And that, Lagree says, is why classes are only 25 minutes.