One of the neatest parts of the U.S. Open is the unfiltered access to players' training sessions. During these behind-the-scenes moments, fans get a peak at how their favorite tennis stars go about their preparation. Novak Djokovic, for example, likes to have some fun.

Recently one fan filmed Marion Bartoli as she prepared for the tournament, and her unconventional workout has gone viral.

In the video, Bartoli starts out with resistance bands around her ankles that are connected to her father, and she eventually takes those off and hits with the bands that are attached to her body. You can see and hear how physically taxing this workout is, even for a world class athlete like Bartoli.

Bartoli lost to Maria Sharapova in the U.S. Open quarterfinals, but her training has clearly paid off over the course of her career. Her intense playing style and impressive longevity are certainly due in part to her grueling workouts.

(H/T to USA Today)

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