---
id: butterfly
name: Butterfly
status: complete
source: free-exercise-db
category: exercise
pattern:
- isolation
equipment:
- machine
difficulty:
  technical_complexity: null
  strength_prerequisite: null
  mobility_prerequisite: null
muscles:
- id: pectoralis_major
  role: primary
- id: deltoid_anterior
  role: secondary
muscle_activation_studies:
  - source_id: schanke_2012
    doi: null
    n: 14
    population: "trained men"
    condition:
      load_pct_1rm: 80
      implement: machine
      elbow_angle_deg: null
      phase: full_rep
      notes: "Normalized to flat barbell bench press = 100%, NOT true %MVIC. Pec deck produced 98% of bench press activation — highest of all chest isolation exercises tested."
    measurements:
      - muscle: pectoralis_major
        mean_pct_mvc: null
        sd: null
  - source_id: botton_2013
    doi: null
    n: 8
    population: "trained males"
    condition:
      load_pct_1rm: null
      implement: machine
      elbow_angle_deg: null
      phase: full_rep
    measurements:
      - muscle: deltoid_anterior
        mean_pct_mvc: 50.0
        sd: null

joint_rom_required:
  shoulder_horizontal_adduction_deg: 90
  elbow_flexion_deg: null
  source: "ACE Fitness"

strength_curve:
  type: bell_shaped
  sticking_point: top_third
  peak_force_position: top
  notes: "Cam-driven resistance profile; primary sticking point at end-range (hands at midline); machine eliminates balance demands"

variations: []
progressions: []
alternatives: []
sources:
- title: "ACE-Sponsored Research: Top 3 Most Effective Chest Exercises"
  author: "Schanke et al."
  year: 2012
  doi: null
  source_id: schanke_2012
  credibility: rct
- title: "Electromyographical analysis of the deltoid muscle between different strength training exercises"
  author: "Botton et al."
  year: 2013
  doi: null
  source_id: botton_2013
  credibility: rct
- title: free-exercise-db
  author: yuhonas (Public Domain)
  credibility: anecdotal
---

# Butterfly

## Execution

1. Sit on the machine with your back flat on the pad.
2. Take hold of the handles. Tip: Your upper arms should be positioned parallel to the
   floor; adjust the machine accordingly. This will be your starting position.
3. Push the handles together slowly as you squeeze your chest in the middle. Breathe out
   during this part of the motion and hold the contraction for a second.
4. Return back to the starting position slowly as you inhale until your chest muscles are
   fully stretched.
5. Repeat for the recommended amount of repetitions.