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Thumb Adduction / Key Pinch Exercise

Draftstrength85%beginner⬤ moderate evidence
View FHIR resourceFHIR R4 ActivityDefinition — the interoperable form of this exercise

Positions & Range of Motion

Start
seated, forearm supported with wrist neutral and quiet, thumb abducted ready to pinch a key edge between thumb pad and radial side of the index finger
End
thumb adducted firmly into the lateral (key) pinch, adductor pollicis squeezing the key for a sustained 5-second hold
Range of Motion
thumb adduction from abducted start to full lateral pinch, then 5-second isometric hold at end range

How to Perform

Strengthening the adductor pollicis through key pinch (lateral pinch) tasks. Adductor pollicis shows nearly equal activation to FPL during pinch, with activity increasing proportionally with force. 79% MVC increase demonstrated after training at 50% MVC.

Watch on YouTube↗

Opens a YouTube search for “Thumb Adduction / Key Pinch Exercise”

Equipment:therapy putty
Starting position: seated

Coaching Cues

  1. 1

    Quiet wrist — adductor pollicis pulls the thumb toward the palm

    (verbal)
  2. 2

    Pinch a key edge between the thumb pad and the index side

    (verbal)
  3. 3

    Hold the squeeze for five steady seconds

    (verbal)
  4. 4

    Free hand on the first web space to feel the contraction

    (tactile)

Evidence-Based Dosing & EMG Data

Recommended Dosing

3×10 reps key pinch holds (5 seconds each), 3x/week. Train at 50% MVC for strength gains [Lyle 1998]

EMG Activation Data

Adductor pollicis nearly equal to FPL during pinch [Cooney 1985]. 79% MVC increase after training at 50% MVC [Lyle 1998]

Muscles Involved (3)

Primary Movers

Adductor Pollicis— Primary during key pinch — activity increases proportionally with force [Cooney 1985]

Secondary Movers

Flexor Pollicis Longus— Co-active during pinch [Cooney 1985]

Synergists & Assistors

Flexor Pollicis BrevisSynergist— MCP stabilization during pinch

Easier Variations ↓

1

Light Pinch

Pinch a soft sponge or tissue. Build tolerance before resistance.

Harder Variations ↑

1

Putty Key Pinch

Pinch therapy putty laterally with progressive resistance levels.

Target Movements (1)

Thumb AdductionFirst Carpometacarpal Joint

Why This Exercise Matters

Everyday activities this exercise helps you do — essential means it directly trains the capacity the task needs:

Gripping a CupOpening a JarDressing — Upper Body

Goals This Helps With

Rehab, performance, prevention, and mobility goals this exercise supports — essential means it's a cornerstone:

Improve Grip Strengthperformance

Evidence Sources (2)