Butler, who said he "wanted to look really strong" in the film, trained with a high-intensity workout for four months prior to the film's shooting.

His training camps are noted for having a low number of high-intensity workouts in full pads, tending to emphasize walking through the game's mental aspects instead.

This means that even while it provides a high-intensity workout, an elliptical machine offers an impact that is similar to that sustained while walking.

"Maybe get in a high-intensity workout?"

Instead they do high-intensity workouts that mix gymnastics, track and field skills and bodybuilding, resting very little between movements.

Not so, though the glucose in them provides easily digested calories, which are important during prolonged, high-intensity workouts.

"I wake up at 7 a.m. and have a high-intensity workout at 7:30," he said.

FreeLetics describes its strength and conditioning program as "a set of predefined high-intensity workouts".

Famiglietti does his high-intensity workouts on one of two tracks.

The high-intensity workout is intended to increase cardiovascular fitness, strength, muscular endurance and flexibility.