1 - Stand upright with your feet shoulder-width apart, holding a filled water bottle in each hand (or one in each hand alternately) with a neutral grip (palms facing each other).
2 - Keep your elbows close to your torso and your upper arms stationary throughout the movement.
3 - With your core engaged and back straight, curl the bottle upward toward your shoulder by flexing your elbow, maintaining the neutral (hammer) grip throughout.
4 - Squeeze your bicep and brachialis at the top of the movement, pausing briefly.
5 - Slowly lower the bottle back to the starting position in a controlled manner, fully extending your arm.
6 - Repeat for the desired number of repetitions on both arms.
