Please choose the correct ending to complete the given sentence: Sports and Fitness: [header] How to flex [title] Make a fist. [step] Keep your shoulders down and relaxed, but allow your shoulder blades to spread to keep your back wide. Form a fist with the arm you want to flex.

Ending1: Take two thumbscrews on each hand, one for each hand. The hand you use to flex should be able to only hold holding your wrist up, flat and straight. Ending2: Start in the center of the circle and bring your right fist together to form a fist. Continue to roll your fist inward, bringing your arm down to form a fist with your fist. Ending3: [title] Curl your fist, then bend your palm. [step] This movement is called mussing-up. Ending4: The simple action of forming a fist already begins to tighten your muscles. It's impossible to fully flex your arms if you don't make a fist first.

Answer format: ending1/ending2/ending3/ending4