It’s no secret that elite skier Lindsey Vonn is just as much a beast in the gym as she is on the slopes. Even Vonn’s most recent injury did not stop her from getting her workouts in. Last week, Vonn posted an Instagram picture of herself performing what is commonly called a “Dragon Flag,” an exercise popularized by Bruce Lee . You’ll see Vonn with her legs, hips and lower torso completely elevated in a straight line, 45 degrees off the bench. To perform this movement properly, Vonn has built immense core strength and stamina, particularly in her transverse abdominus (the deepest layer of abdominal muscles), obliques, glutes and hips.

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To try the move, lie back on a bench and grab the edge behind your head with your hands. Brace your arms and shoulders and tighten your core, then lift your legs in a straight line, like you would in a Reverse Crunch. Engage your glutes and raise your hips to create a straight line with your whole lower body. Slowly lower your hips and legs, maintaining that straight line. Ideally, your lower back does not touch the bench between reps.

In the (pieced together) clip below of Bruce Lee performing the Dragon Flag, his upper body remains completely still, and he does not take his legs up past 45 degrees. Lee actually demonstrates some flexibility in the line of his body, bending slightly at the hips on the downward movement.

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Most trainers would not recommend bending at the hips and would advise taking your lower body fully vertical, as demonstrated in Rocky IV.

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Vonn has also been throwing a few punches lately, complementing her Dragon Flag.