Close-grip barbell curls target the long (outer) head of the biceps, which makes up the biceps peak.
PROSECUTION
Wide-grip barbell curls allow you to use more weight and stress the short (inner) head of the biceps more.
EVIDENCE
The biceps muscles are composed of two di erent heads that start from di erent anatomical locations in the shoulder region, but verge onto one common tendon that crosses the elbow joint. You can change the emphasis placed on either head by changing up the exercise form, such as grip width on the barbell.
When you hold the bar with a shoulder-width grip, your arms are in what is called the anatomical position — straight down and not rotated.
When you hold the bar with a wider-than-shoulder-width grip, your arms turn out at the shoulder joint, which is known as external rotation. The wider you go on the bar, the more external rotation you have and the more involvement you have from the inner (short) biceps head. This grip also shortens the path the barbell takes during the curl, allowing you to use slightly more weight on barbell curls.
When you hold the bar with a narrower-than-shoulder-width grip, your arms turn in, which is known as internal rotation. The narrower your grip, the more internal rotation you have and the more involvement you have from the outer (long) head, which is important for building up the peak.
VERDICT: CLOSE GRIP
Because most guys want to build their biceps peaks and the long head makes up a good proportion of the biceps mass, your best bet is to focus more on narrow-grip barbell curls — using a grasp that is about hip width or slightly closer.
SENTENCING
The best way to build the balance of overall biceps mass is by frequently changing up your hand position for barbell curls between narrow grip, shoulder width and beyond shoulder width. While the narrow grip is great for focusing on the long head for better peak development, the standard shoulder-width grip hits both heads and the wide grip not only hits the short head best, but also allows you to go a bit heavier for placing greater overload on the biceps.
