You flex your arms. Fourteen inches. The same as six months ago. You’ve been doing curls religiously, but nothing changes.
Meanwhile, other men have thick, muscular arms that fill out sleeves. You wonder: what are they doing differently?
The truth: Building bigger arms requires understanding anatomy and training accordingly. Your biceps have two heads (long and short) needing different angles. Your triceps have three heads making up two-thirds of arm size. Most men only do standard curls and wonder why arms don’t grow.
I’m Will Duru, a personal trainer with 10+ years’ experience in London. I’ve helped hundreds of men add 2 to 4cm to their arms in 6 to 12 months.
What I’ve learned: Bigger arms require direct work twice weekly (12 to 16 sets total), progressive overload on key movements, and training all heads of biceps and triceps. Compound pressing and pulling alone won’t maximise arm developmen
The Arm Anatomy You Need to Know
Biceps: Two Heads, Different Functions
Long head (outer bicep):
- Creates bicep “peak” when flexed
- Best trained with arms behind body (incline curls, drag curls)
- Emphasised with narrow grip
Short head (inner bicep):
- Creates bicep “width” from front
- Best trained with arms in front of body (preacher curls)
- Emphasised with wide grip
Why both matter: Training only standard curls primarily hits short head. Long head remains underdeveloped, bicep looks flat despite decent size.
Will’s bicep observation: “Client doing only straight bar curls for 8 months. Biceps have some size but zero peak. We add incline dumbbell curls (targets long head). Four months later, visible peak appears. Complete bicep development requires hitting both heads.”
Triceps: Three Heads, Two-Thirds of Arm Size
Long head (inner tricep):
- Largest tricep head, most mass potential
- Best trained with arms overhead (overhead extensions)
- Creates thickness when viewed from side
Lateral head (outer tricep):
- Creates horseshoe shape
- Best trained with arms at sides (pushdowns, kickbacks)
- Visible when arm extended
Medial head (deep tricep):
- Lies underneath other heads
- Trained by all tricep exercises
- Provides overall arm thickness
Why triceps matter more: Triceps are two-thirds of upper arm mass. Client with 14-inch arms: 5 inches biceps, 9 inches triceps. Prioritising triceps creates bigger arms faster than focusing only on biceps.
Will’s tricep priority: “Client obsessed with biceps, neglects triceps. Arms stuck at 35cm for 6 months. We add proper tricep volume (overhead extensions, close-grip bench). Four months later: arms 37cm. Triceps drive arm size.”
Why Standard Arm Training Fails
Problem 1: Insufficient Volume
What most men do: One arm exercise per week (biceps on back day, triceps on chest day), maybe 6 to 9 sets weekly total.
Why it fails: Research shows 12 to 20 sets weekly per muscle group for optimal growth. Six sets is maintenance volume at best, not growth stimulus.
What you need: Dedicated arm training twice weekly, 12 to 16 sets total per muscle (6 to 8 sets per session).
Will’s volume prescription: “Client doing 6 weekly sets biceps, 6 sets triceps. Arms not growing. We increase to 14 sets each muscle (two dedicated arm sessions weekly). Arms finally grow, 1cm added in 8 weeks.”
Problem 2: No Progressive Overload
What most men do: Dumbbell curls with 12kg forever, cable pushdowns same weight stack month after month.
Why it fails: No increasing stimulus equals no adaptation (muscle growth). Your body has zero reason to build bigger arms if you’re lifting same weights indefinitely.
What you need: Systematic weight increases every 2 to 4 weeks tracked via 12REPS.
Will’s arm progression: “Client curling 10kg dumbbells for 8 months, arms stuck. We implement tracking and progressive overload. Twelve months: curling 18kg dumbbells, arms grown 2cm. Progressive overload is non-negotiable.”
Problem 3: Only Training One Head Per Muscle
Biceps mistake: Only standard barbell curls (primarily short head), neglecting long head exercises (incline curls).
Triceps mistake: Only pushdowns (lateral head emphasis), neglecting overhead extensions (long head emphasis).
The result: Incomplete arm development. Decent size but lacking shape, peak, or thickness.
Will’s complete arm development: “Client trains all bicep and tricep heads: standard curls (short head), incline curls (long head), overhead extensions (tricep long head), pushdowns (tricep lateral head). Arms look dramatically better than same circumference with incomplete training.”
The Complete 2-Day Arm Programme
Training Frequency and Structure
Optimal frequency: Twice weekly with 48 to 72 hours between sessions.
Weekly split example:
- Monday: Arm Workout 1 (Biceps focus)
- Thursday: Arm Workout 2 (Triceps focus)
- OR Tuesday/Friday, OR Wednesday/Saturday
Why twice weekly: Arms recover faster than legs or back. Higher frequency (twice weekly) produces superior growth compared to once weekly.
Progressive overload: Increase weight when hitting top end of rep range for all sets. Example: Cable pushdowns 30kg × 12, 12, 12 → increase to 32.5kg next session.
ARM WORKOUT 1: BICEPS EMPHASIS (Monday)
Exercise | Equipment | Sets | Reps | Weight Progression | Rest |
Barbell Curls | Barbell (straight or EZ) | 3 | 8-10 | Start 20-25kg, add 2.5kg when hit 10,10,10 | 2 min |
Incline Dumbbell Curls | Dumbbells, incline bench | 3 | 10-12 | Start 10-12kg DBs, add 2kg when hit 12,12,12 | 90 sec |
Cable Hammer Curls | Cable with rope attachment | 3 | 12-15 | Start light, add weight when hit 15,15,15 | 90 sec |
Close-Grip Bench Press | Barbell, flat bench | 3 | 8-10 | Start 40-50kg, add 2.5kg when hit 10,10,10 | 2 min |
Cable Tricep Pushdowns | Cable with straight bar | 3 | 12-15 | Start moderate, add weight when hit 15,15,15 | 90 sec |
Overhead Dumbbell Extension | Dumbbell | 2 | 12-15 | Start 12-16kg, add 2kg when hit 15,15 | 90 sec |
Total: 17 sets (9 biceps, 8 triceps) – Biceps emphasis with tricep maintenance
ARM WORKOUT 2: TRICEPS EMPHASIS (Thursday)
Exercise | Equipment | Sets | Reps | Weight Progression | Rest |
Close-Grip Bench Press | Barbell, flat bench | 4 | 6-8 | Start 50-60kg, add 2.5kg when hit 8,8,8,8 | 2.5 min |
Cable Overhead Extension | Cable with rope | 3 | 10-12 | Start moderate, add weight when hit 12,12,12 | 2 min |
Dumbbell Kickbacks | Dumbbells, bench | 3 | 12-15 | Start 6-8kg DBs, add 1kg when hit 15,15,15 | 90 sec |
Barbell or EZ-Bar Curls | Barbell | 3 | 8-10 | Start 22-27kg, add 2.5kg when hit 10,10,10 | 2 min |
Cable Preacher Curls | Cable with straight bar | 3 | 12-15 | Start light, add weight when hit 15,15,15 | 90 sec |
Dumbbell Hammer Curls | Dumbbells | 2 | 12-15 | Start 10-12kg DBs, add 2kg when hit 15,15 | 90 sec |
Total: 18 sets (10 triceps, 8 biceps) – Triceps emphasis with bicep maintenance
Weekly Arm Training Summary
Muscle | Workout 1 Sets | Workout 2 Sets | Total Weekly |
Biceps | 9 | 8 | 17 sets |
Triceps | 8 | 10 | 18 sets |
Total weekly arm volume: 35 sets (17 biceps + 18 triceps) – Optimal growth stimulus
Exercise Breakdowns: How to Execute Perfectly
Barbell Curls (Short Head Emphasis)
Setup: Stand holding barbell, hands shoulder width, palms up.
Execution: Curl bar to chest keeping elbows pinned to sides. Squeeze biceps at top. Lower controlled (2 to 3 seconds).
Will’s cue: “No swinging or momentum. If you need to rock your body, weight is too heavy. Clean reps only.”
Incline Dumbbell Curls (Long Head Emphasis)
Setup: Sit on incline bench (45 degrees), dumbbells hanging at sides, arms behind body.
Execution: Curl dumbbells up whilst keeping upper arms stationary. Long head gets stretched at bottom, fully contracted at top.
Will’s cue: “This targets bicep peak. Let arms hang fully behind body at bottom for maximum long head stretch.”
Cable Hammer Curls (Brachialis and Forearms)
Setup: Stand facing cable machine, rope attachment, palms facing each other.
Execution: Curl rope towards shoulders keeping palms neutral (facing each other throughout). This hits brachialis (underneath bicep) and forearms.
Will’s cue: “Hammer grip emphasises thickness underneath bicep. Critical for overall arm development.”
Close-Grip Bench Press (Tricep Mass Builder)
Setup: Lie on bench, grip barbell hands 30 to 40cm apart (closer than regular bench press).
Execution: Lower bar to lower chest, press up explosively. Keep elbows closer to body than wide-grip bench press.
Will’s cue: “Best mass builder for triceps. You can load heavy weight safely. Client added 15kg to close-grip over 6 months, triceps grew dramatically.”
Cable Overhead Extension (Long Head Emphasis)
Setup: Face away from cable machine, rope attachment overhead, arms extended.
Execution: Lower rope behind head by bending elbows, keeping upper arms stationary. Stretch long head fully, then extend arms overhead.
Will’s cue: “This targets tricep long head (inner tricep). Creates thickness when viewed from side. Essential for complete tricep development.”
Cable Tricep Pushdowns (Lateral Head Emphasis)
Setup: Face cable machine, straight bar or rope attachment chest height.
Execution: Push bar or rope down by extending elbows, keeping upper arms stationary at sides. Squeeze triceps at bottom.
Will’s cue: “This targets lateral head (outer tricep). Creates horseshoe shape. Keep elbows pinned to sides throughout.”
This Is Where 12REPS Maximises Arm Growth
The arm training challenge: executing structured workouts with consistent progressive overload on isolation exercises.
Most men fail at arm growth because they do random curls and extensions with no progression tracking.
12REPS solves this:
Instant Arm Workouts Generated
What 12REPS does: Generate complete arm workouts using YOUR available equipment (barbells, dumbbells, cables).
How it works: Select “arm training,” choose equipment available, get instant workout with barbell curls, incline dumbbell curls, cable pushdowns, overhead extensions.
Try 12REPS free for 7 days. Get structured arm workouts twice weekly. Stop doing random curls.
Track Progressive Overload on Every Exercise
What 12REPS provides: Log every arm workout. App shows what weight you curled or pushed last session.
Example: Last session cable pushdowns 27.5kg × 12, 11, 10. Today’s target: beat it (aim for 27.5kg × 12, 12, 11 or 13, 12, 11). Log actual: 27.5kg × 12, 12, 12 (progression achieved, increase to 30kg next session).
Will’s arm tracking: “Client not tracking does random dumbbell curls, arms stuck at 35cm for 5 months. We implement 12REPS tracking with progressive overload. Eight months: dumbbell curls 12kg to 18kg, arms 35cm to 37cm. Tracking equals arm growth.”
Try 12REPS free for 7 days. Track barbell curls, cable pushdowns, overhead extensions. See arm strength increasing weekly.
Exercise Library With Perfect Form
What 12REPS provides: Video demonstrations for every arm exercise. Barbell curls, incline curls, close-grip bench, overhead extensions, all with proper form.
Why form matters for arms: Poor curl form (swinging, momentum) builds nothing. Proper form (controlled, full range, squeeze at contraction) maximises bicep stimulus.
Will’s form requirement: “Client swinging 16kg dumbbells with terrible form, biceps not growing. Watch 12REPS curl video, learn proper technique (no momentum, controlled eccentric, squeeze at top). Drop to 12kg with perfect form, biceps finally grow.”
Your Arm Growth Timeline
Months 1 to 3: Strength Foundation
What happens: Rapid strength gains (neurological adaptation), minimal size change yet.
Typical progress:
- Arms: 35cm to 35.5cm (0.5cm gained, mostly water retention)
- Strength: Barbell curls 20kg to 27kg, cable pushdowns 25kg to 35kg
- Visual: Slightly fuller pump post-workout, no obvious size change
Will’s months 1 to 3: “Client frustrated week 8, arms barely changed. I explain strength up 30% already (curls 20kg to 26kg), muscle growth comes next. Keep training, keep progressing weight.”
Months 4 to 8: Visible Growth
What happens: Actual muscle growth occurring, arms visibly bigger.
Typical progress:
- Arms: 35.5cm to 37cm (1.5cm additional gain)
- Strength: Barbell curls 27kg to 32kg, cable pushdowns 35kg to 42kg
- Visual: Shirts fitting tighter around arms, colleagues notice
Will’s months 4 to 8: “Client arms 35cm to 37cm. Total 2cm gain from baseline. Sleeves genuinely tighter, people commenting. This is when arm training becomes addictive.”
Months 9 to 12: Impressive Development
What happens: Arms genuinely muscular, visible peak and horseshoe.
Typical progress:
- Arms: 37cm to 38cm (1cm additional gain)
- Strength: Barbell curls 32kg to 37kg, cable pushdowns 42kg to 50kg
- Visual: Clear bicep peak, visible tricep horseshoe, 3cm total gain from baseline
Will’s year 1 arm growth: “Client year 1: arms 35cm to 38cm (3cm gain), curls 20kg to 37kg, pushdowns 25kg to 50kg. From average arms to genuinely impressive. Exactly what happens with proper volume, progressive overload, twice weekly frequency.”
Common Arm Training Mistakes
Mistake 1: Training Arms Only Once Weekly
Why it fails: Arms recover quickly (unlike legs or back). Once weekly frequency is suboptimal.
The fix: Twice weekly arm training with 48 to 72 hours between sessions.
Mistake 2: No Progressive Overload
Why it fails: Curling 12kg dumbbells forever provides zero stimulus for growth.
The fix: Track every workout via 12REPS, systematically increase weight every 2 to 4 weeks.
Mistake 3: Only Training One Bicep or Tricep Head
Why it fails: Incomplete arm development. Decent size but lacking shape.
The fix: Include exercises for all heads: standard curls (bicep short head), incline curls (long head), overhead extensions (tricep long head), pushdowns (lateral head).
Mistake 4: Using Momentum Instead of Control
Why it fails: Swinging weight, rocking body means biceps barely working.
The fix: Control throughout movement, 2-second negatives, squeeze at contraction. Drop weight if form breaks down.
The Bottom Line
Building bigger arms requires:
✅ Direct arm training twice weekly (not just biceps on back day, triceps on chest day)
✅ Adequate volume (12 to 18 sets per muscle weekly, split across two sessions)
✅ Progressive overload (weight increasing every 2 to 4 weeks tracked via 12REPS)
✅ Training all heads (bicep long and short, tricep long and lateral)
✅ Perfect form (controlled reps, no momentum, full range of motion)
✅ Equipment variety (barbells for mass, dumbbells for stretch, cables for constant tension)
✅ Patience (realistic gain is 2 to 4cm in 12 months)
Will’s arm training experience: “Client arms stuck 35cm for 6 months doing random curls once weekly. We implement twice weekly structured training with progressive overload tracked via 12REPS. Twelve months: arms 35cm to 38cm (3cm gain), curls 20kg to 37kg, pushdowns 25kg to 50kg. Frequency, volume, and progression changed everything.”
Why 12REPS maximises arm growth: Instant arm workouts generated (using YOUR equipment), track progressive overload on every exercise (curls, pushdowns, extensions), 1,500+ exercise videos (perfect form on all movements).
Try 12REPS free for 7 days. Get structured twice-weekly arm training, track progressive overload on barbell curls and cable pushdowns, ensure systematic arm growth. Stop doing random curls with same dumbbells. Start building arms with intelligent training.
Train arms twice weekly using complete 2-day programme. Hit all bicep and tricep heads. Use progressive overload tracked via 12REPS. Add 2 to 4cm to arms in 12 months. Fill out sleeves. Build arms worth showing.
References
- Schoenfeld, B.J., Ogborn, D., Krieger, J.W. (2016). Effects of Resistance Training Frequency on Measures of Muscle Hypertrophy. Sports Medicine, 46(11), 1689-1697. https://doi.org/10.1007/s40279-016-0543-8
- Baz-Valle, E., Balsalobre-Fernández, C., Alix-Fages, C., et al. (2022). A Systematic Review of The Effects of Different Resistance Training Volumes on Muscle Hypertrophy. Journal of Human Kinetics, 81, 199-210. https://doi.org/10.2478/hukin-2022-0017
