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Smith Machine Skull Crusher
A lying triceps extension on the Smith machine that isolates the triceps brachii for strength and hypertrophy; fixed path aids stability and heavier loads.
About Exercise
Equipment
Smith Machine, Flat Bench
Difficulty
2/5 • Intermediate
Primary Muscle Groups
Triceps
Secondary Muscles
Shoulders
Accessory Muscles
Forearms
Popularity Score
7
Goals
Training Style
Setup Requirements
Requires Rack
No
Requires Bench
Yes
Requires Spotter
No
Space Needed
Small
Noise Level
Low
Muscle Breakdown
View Muscle MapTriceps
10/10Long Head, Lateral Head, Medial Head
Shoulders
3/10Anterior Delts
Forearms
2/10Flexors
Programming
Typical Rep Range
8-15 reps
Rest Between Sets
60-90 seconds
How to Perform
Position a flat bench under the Smith machine so the bar aligns over your forehead when arms extended. Lie back with feet flat, grip bar slightly narrower than shoulders.
- Unrack bar by rotating, extend arms above chest with slight elbow bend.
- Inhale and bend elbows to lower bar toward forehead, keep upper arms stationary.
- Stretch triceps at bottom position.
- Exhale and extend elbows to push bar up, squeeze triceps at top.
- Avoid locking elbows, repeat for reps.
- Rerack bar after set.
Coaching Tips
Form Cues
- Tuck elbows in
- Upper arms stationary
- Squeeze triceps hard
- Drive shoulders into bench
Breathing
Inhale during lowering, exhale during extension while bracing core.
Tempo
3-1-1
Range of Motion
Lower until elbows are at 90 degrees or bar nears forehead; extend to straight arms without hyperextension.
Safety
Safety Notes
- Set safety catches at bottom position
- Use light weight to master form
- Stop if elbow pain occurs
- Warm up elbows and shoulders
- Maintain straight wrists
Spotting
Not required; use Smith machine safeties for protection during failure.
Common Mistakes
- Flaring elbows outward
- Locking elbows at top
- Arching lower back
- Using momentum to lift
When to Avoid
- Acute elbow pain
- Shoulder impingement
- Wrist instability
Flexibility Needed
- Shoulder flexion to 180 degrees
- Elbow extension mobility
Build Up First
- Master basic triceps extension form
- Comfort with overhead pressing
Also known as
Smith Machine Lying Triceps Extension, Smith Machine French Press
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