Your bicep peak. That golf ball sized muscle at the top of your arm when you flex. It's genetic—the distal attachment of your biceps determines how high the peak goes—but you can absolutely maximise what you've got.
The issue: most lads train biceps wrong. High-rep curls on cable machines, ego-lifting on barbell curls, zero brachialis work. They end up with soft, puffy arms instead of peaked, dense muscle.
Sam Sulek, CBum, and most top physique athletes all follow a similar arm protocol: maximise the brachialis (the deeper muscle under the bicep), then work peak height and width separately.
Trained biceps twice a week for a year using only barbell curls and saw almost no peak development. Switching to incline dumbbell curls (which stretch the long head) and concentration curls (which isolate the peak contraction) added visible height to my bicep within four months. The long head is the peak muscle — and it only grows when you train it at full stretch.
The Anatomy: Bicep vs Brachialis
Biceps Brachii Two heads: the long head (outer, creates the peak) and short head (inner, creates the width and size). When you flex in the mirror, most of what you see is the bicep.
Brachialis Sits under the biceps. When you develop it, it literally pushes the bicep up and out, making your arms look more peaked and bigger. A lot of lifters ignore this and it's a massive mistake.
Muscle hypertrophy responds to both load and stretch-mediated tension - supporting the use of incline curls and full range of motion for bicep peak development.
Here's the reality: a bicep 3cm smaller with a huge brachialis looks more impressive than a bigger bicep with no brachialis development.
Peak vs Width: The Distinction
For Peak (the height of the muscle):
- Train the long head of the bicep with heavy, full-range work.
- Hammer curls (neutral grip) activate the brachialis AND long head.
- Incline dumbbell curls stretch the long head maximally.
- Cable curls with high starting position (arm extended above shoulder).
For Width (making the arm bigger overall):
- Train the short head with close-grip curls or EZ-bar curls.
- High-rep supinated curls (palms facing out).
- Machine curls that hit the lower portion of the bicep.
For Density (that dense, peaked look):
- Heavy compound curls (barbell or dumbbell), 4-6 reps.
- Weighted hammer curls, 6-8 reps.
- Brachialis-focused work, 8-12 reps.
The Exercise Hierarchy
Tier 1: Peak Builders
Incline Dumbbell Curls Full stretch, isolated, magical for peak. The incline position puts your arms behind your torso, maximising the long head stretch. 3-4 sets x 6-10 reps. Do these heavy.
Hammer Curls (heavy) Neutral grip, hits brachialis + long head bicep. This is your most important arm exercise if peak matters. 3-4 sets x 6-10 reps. Go heavy here.
Standing Barbell Curls Pure mass and strength. The barbell forces strict form. 3-4 sets x 6-10 reps. Not fancy, but effective.
Tier 2: Width & Brachialis
Machine Curls (low position) Constant tension on the lower bicep (short head insertion). 3 sets x 10-12 reps. The pump here is insane.
Hammer Curls (lighter, higher reps) Still hitting brachialis but with metabolic stress. 3 sets x 12-15 reps.
EZ-Bar Curls (close grip) Short head emphasis. Less wrist strain than barbell. 3 sets x 8-12 reps.
Tier 3: Volume & Pump
Cable Curls Constant tension, lighter weight, high reps. 3 sets x 12-15 reps.
Dumbbell Curls (supinated, standing) Functional, hypertrophy-friendly. 3 sets x 8-12 reps.
Concentration Curls Mind-muscle connection, peak contraction, lighter weight. 3 sets x 12-15 reps.
Hammer Curls vs Supinated Curls
Hammer Curls (neutral grip)
- Primary movers: brachialis, long head bicep, brachioradialis (forearm).
- Angle: significantly more brachialis activation than supinated curls.
- Weight: you can use heavier dumbbells with hammer curls than supinated curls (less elbow stress).
- Best for: peak, density, arm thickness, forearm development.
- Reps: 6-12 reps.
- Frequency: 2-3x per week if you care about arms.
Supinated Curls (palms facing out)
- Primary movers: short head bicep, some long head, minimal brachialis.
- Angle: maximizes bicep peak if the arm is in full supination (hard to achieve with full range).
- Weight: lighter than hammer curls for most people.
- Best for: bicep isolation, mind-muscle connection.
- Reps: 8-15 reps.
- Frequency: 1-2x per week.
The verdict: hammer curls are objectively more useful for building impressive arms. But both have a place. Most programs should be 60% hammer, 40% supinated.
How the Pros Train Arms
Sam Sulek's Approach
- High frequency (arms hit 4-5x per week).
- Hammer curl focus: heavy, consistent, progressive overload.
- Low-to-moderate volume per session (3-4 exercises).
- High intensity: mostly 6-10 rep range with heavy weight.
- Low body fat (training year-round lean): makes arms pop regardless of size.
CBum's Approach
- 2-3 dedicated arm days per week.
- Heavy incline dumbbell curls for peak.
- Hammer curl superset with machine curls for pump and density.
- High volume on secondary exercises (cables, machines, higher reps).
- Emphasis on mind-muscle connection and controlling the weight.
Key Takeaway: both prioritise heavy compound curls, hit arms frequently, and keep body fat low to display the peaks.
A 4-Day Arm-Focused Program
If you care about your arms, they deserve their own days.
Day 1: Peak & Density
- Incline Dumbbell Curls: 4 x 6-8 reps
- Barbell Curls: 3 x 8-10 reps
- Machine Curls: 3 x 12 reps
- Cable Curls: 2 x 15 reps
Day 2: Brachialis & Thickness
- Heavy Hammer Curls: 4 x 6-8 reps
- EZ-Bar Curls (close grip): 3 x 8-10 reps
- Machine Curls (high position): 3 x 10-12 reps
- Dumbbell Curls: 2 x 12 reps
This hits both heads, the brachialis, and provides enough volume and frequency to drive growth. Progressive overload is essential—add weight or reps every 1-2 weeks.
Realistic Expectations
You can gain 0.5-1cm of arm mass per 5-8kg of bodyweight gained. If you're in a surplus and training arms correctly, expect 0.5-1cm every 2-3 months.
Peak height is genetic. But with brachialis development and low body fat, you can make even a naturally short peak look impressive.
The real difference between impressive arms and mediocre arms isn't size alone—it's density, peak height, and the fact that they look like something was actually built there.
Bicep peak is built by the long head — prioritise incline dumbbell curls for stretch and concentration curls for peak contraction, training biceps twice per week.
If you are training arms twice a week and not already taking creatine, this is the supplement with the deepest evidence base for strength and rep performance.
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