The Narrow Muscle-Up is an advanced variation where hands are positioned closer than shoulder-width on the bar. Grip the bar narrow and pull your chest towards it, transitioning your body over by pulling yourself up and forward. Press down into the bar to reach the locked-out position, then lower with control. This targets back, chest, shoulders, and arms, requiring significant upper body strength and stability. Master the standard muscle-up before attempting the narrow version, ensuring proper form to avoid injury.