Your bicep isn't one muscle—it's two. The biceps brachii (literally "two-headed muscle of the arm") has a long head and a short head. Understanding the difference helps you train smarter.
Basic Anatomy
Long head:
• Located on the outer/lateral part of your upper arm
• Originates at the supraglenoid tubercle of the scapula (shoulder blade)
• Crosses the shoulder joint
• Responsible for the "peak" when you flex
Short head:
• Located on the inner/medial part of your upper arm
• Originates at the coracoid process of the scapula
• Also crosses the shoulder joint
• Contributes to bicep width and thickness
Both heads merge into a single tendon that attaches to the radius bone in your forearm (the radial tuberosity).
How to Emphasize the Long Head (For Peak)
Because the long head crosses the shoulder joint and originates behind the short head, it's stretched more when your arm is behind your body. Exercises that start with your arm in this position emphasize the long head:
Best long head exercises:
• Incline dumbbell curls (arms hang behind torso)
• Drag curls (elbows move backward)
• Behind-the-back cable curls
• Narrow-grip barbell curls
Key principle: Shoulder extension (arm behind body) + narrow grip = long head emphasis
How to Emphasize the Short Head (For Width)
The short head is emphasized when your arm is in front of your body (shoulder flexion). This position shortens the long head, making it less efficient, and shifts work to the short head:
Best short head exercises:
• Preacher curls (arms in front of body)
• Spider curls
• Concentration curls
• Wide-grip barbell curls
• High cable curls
Key principle: Shoulder flexion (arm in front of body) + wide grip = short head emphasis
Which Should You Focus On?
It depends on your goals and current development:
Focus on long head if:
• You want a higher bicep peak
• Your arms look flat when flexed
• You've been doing mostly preacher curls
Focus on short head if:
• You want wider/thicker looking arms from the front
• Your biceps lack width
• You've been doing mostly incline curls
For most people: Train both with a balanced approach. Include exercises that emphasize each head over the course of your training week or cycle.
Sample Balanced Bicep Workout
Long head emphasis:
1. Incline dumbbell curl: 3 sets x 10-12
Short head emphasis:
2. Preacher curl: 3 sets x 10-12
Overall development:
3. Standing barbell curl: 3 sets x 8-10
Brachialis (for completeness):
4. Hammer curl: 2 sets x 12-15
This hits both heads specifically while also providing overall bicep stimulation.
The Role of Genetics
Your bicep peak potential is significantly influenced by genetics:
Muscle belly length: Longer muscle bellies (shorter tendons) generally create better peaks. This is genetic and can't be changed.
Insertion points: Where your bicep tendon attaches to the bone affects how your bicep looks. Higher insertions typically mean less peak potential.
You can maximize what you have with training, but you can't change your genetic structure. Some people will naturally have higher peaks; others will have flatter, wider biceps regardless of training.
Common Misconceptions
"You can isolate one head completely"
False. Both heads always contract together during elbow flexion. You can only shift emphasis, not isolation.
"The inner bicep and outer bicep are different muscles"
Misleading. The short head (inner) and long head (outer) are two heads of the same muscle, not separate muscles.
"Grip width doesn't matter"
False. Grip width does affect relative head activation, though the effect is modest.
The Bottom Line
The long head and short head of your biceps serve the same function but respond slightly differently to exercise variations. For complete bicep development, include exercises that emphasize each head—incline curls for long head, preacher curls for short head—along with standard curls for overall development.
Don't overcomplicate it. A few well-chosen exercises covering different positions will develop both heads effectively.