Battle ropes

Battle ropes are a cardio exercise where the arms wave two heavy ropes.

Hold one end of a rope in each hand, feet shoulder-width apart, knees slightly bent, and torso leaning forward slightly.

Raise and lower your arms rapidly, either alternating or together, to create waves all the way to the anchor point.

Keep your back straight and your knees bent: the movement originates from the shoulders, not the lower back.