The pull-up is a fundamental bodyweight exercise that involves grasping an overhead bar and pulling the body upward until the chin clears the bar. This movement is highly effective for developing upper body pulling strength and increasing the width of the back. As a compound exercise, it engages multiple muscle groups simultaneously. This makes it one of the most efficient ways to build a strong physique and provides a substantial challenge to the muscles of the back and arms.
The Standard Definition: Overhand Grip
The universally accepted definition of a pull-up requires the use of an overhand grip, technically known as a pronated grip. In this position, the palms face away from the body, with the knuckles pointing toward the user. This grip is the defining characteristic that separates the pull-up from its close relative.
For the standard pull-up, the hands are typically placed slightly wider than shoulder width apart. This wider placement is biomechanically advantageous for maximizing the recruitment of the large back muscles. Placing the hands in this pronated position emphasizes back strength over arm strength.
Understanding the Underhand Grip
The underhand grip, or supinated grip, is where the palms face toward the user and the knuckles point away. This specific hand position technically defines a different exercise known as the chin-up. While many people use the terms “pull-up” and “chin-up” interchangeably, the change in wrist and hand rotation alters the mechanics of the movement.
Chin-ups are typically performed with a narrower grip, often at or slightly inside shoulder width. This closer, underhand placement provides a different mechanical advantage that shifts the focus of the exercise. This grip variation is a common starting point for individuals building foundational pulling strength.
Muscle Focus: How Grip Changes the Workout
The difference in grip directly influences which muscles are recruited most heavily during the movement. The overhand pull-up places a greater demand on the latissimus dorsi, the broad muscles of the back responsible for creating the desired V-taper physique. The pronated grip minimizes the mechanical advantage of the biceps, forcing the back muscles to generate most of the pulling force. The latissimus dorsi exhibits higher activation during the pull-up compared to the chin-up, making it superior for back width development.
Conversely, the underhand chin-up significantly increases the activation of the biceps brachii, the primary muscle on the front of the upper arm. The supinated grip allows for greater elbow flexion, which maximizes the involvement of the biceps. The chin-up also increases activation in the brachialis and the pectoralis major, or chest muscle, compared to the pull-up. Therefore, while both exercises build overall pulling strength, the pull-up is a back-focused movement, and the chin-up is more arm-dominant.