Grip a pull-up bar with your hands close together (narrow grip) and hang with your arms fully extended. Engage your core and pull your body upward by flexing your elbows until your chin reaches or passes the bar, focusing on contracting the brachialis and biceps. Pause briefly at the top, then lower yourself back down with control until your arms are straight. Maintain a straight torso and avoid swinging throughout the movement.
Log your brachialis narrow pull ups sets in 1RM.fit and watch your estimated 1RM update automatically as you get stronger.