[Standing Barbell Curl] Exercises the biceps, brachialis, and brachioradialis. Hold the barbell with your hands behind your back, with the grip shoulder-width apart. Stand upright, raise your head, and lift your chest. Your shoulders should be lowered and slightly extended, and your knees should be slightly bent. Strictly keeping your elbows close to your sides, curl upwards smoothly - the range of motion is from 15-115 degrees. Perform a brief peak contraction before controlled reduction. Action reminder: Keep your body upright and do not use your body’s explosive power.