Stand with your feet shoulder-width apart and hold a barbell in one hand, palm facing up. Rest your opposite hand on your thigh for support. Keeping your upper arm stationary, exhale and curl the weight up towards your shoulder. Pause for a moment at the top, squeezing your biceps. Inhale and slowly lower the weight back down to the starting position. Repeat for the desired number of repetitions, then switch arms.
GIF