It’s the Loch Ness monster of exercises. People speculate about the human flag, but it’s rarely spotted—and proving its existence in your exercise repertoire will bring you great fame, at least among fellow gym goers. Sidney Wilson, a New York trainer to celebrities, gives you the workout that will get you horizontal if you put in the work.
Hang from a chin-up bar and bend your knees 90 degrees. Swing your legs to the right side as if you were trying to touch your right hip to the bar. “As you swing, push with your left arm,” says Wilson. Repeat on the opposite side and continue so you develop a rhythm. Do as many reps as you can and then rest 30 seconds. When you improve, do it with your legs straight. Repeat for as many sets as possible. Afterward, swing to one side and hold your legs out as long as you can—“try to hold them at a 45- degree angle,” says Wilson.
Lie on the floor on your left side with legs straight and your right hand behind your head. Raise your legs and torso, trying to touch
your elbow to your knee (a V-up). Do three to four sets of 10 reps.
Lie on your back and start moving your legs as if you were pedaling a bicycle. Twist and crunch your torso so your elbow touches your opposite knee on each rep. “Count from 10 down to one, then nine down to one, eight down, and so on until you reach one,” says Wilson. Rest, and then crunch straight up while raising your opposite knee and elbow so they touch (you’ll look like you’re sprinting). Count from one to 10, then two to 10, and so on up to 10.