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Shoulder Flexibility (Zipper / Back-Scratch) Test

Evidence-grounded — sourced from Fysiqal's fitness knowledge graph· 2 min read
flexibilityshoulderzipper-testback-scratchtestromupper-body

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In one line

Reach one hand over the shoulder and the other up the back to see if the fingers meet behind you; the gap (or overlap) indexes shoulder mobility and is scored as a distance.

Detail

The shoulder flexibility test — the "zipper test" (Apley scratch) and the back-scratch test (Senior Fitness Test version) — assesses combined shoulder flexion, extension, internal and external rotation, plus scapular mobility.

Protocol: reach one arm over the same-side shoulder and down the back (shoulder flexion + external rotation), and the other arm behind the back and up (extension + internal rotation), attempting to touch/overlap the fingers between the shoulder blades. Measure the distance between fingertips: overlap = positive, touching = 0, gap = negative (cm/in). Test both sides (the dominant/throwing side often differs). Take the best of 2 trials per side.

Interpretation: asymmetry between sides is informative (common in throwing athletes and after shoulder injury). The back-scratch variant has Senior Fitness Test norms by age/sex for older adults. It is a quick screen, not a substitute for goniometric ROM when precision is needed.

Key facts

  • Assesses combined shoulder flexion/extension + internal/external rotation + scapular motion.
  • One hand over the shoulder, the other up the back; score the fingertip gap/overlap (cm/in; overlap positive).
  • Test both sides; note asymmetry; best of 2 trials/side.
  • Senior Fitness Test back-scratch variant has age/sex norms for older adults.

Connections

  • sit-and-reach-test — lower-body flexibility companion.
  • goniometry — precise joint-angle alternative.
  • flexibility-norms — interpretation context.
  • shoulder-joint-rom — the joint ROM being assessed.
SourceCurrent guideline bodies
Apley scratch test (clinical); Rikli & Jones, Senior Fitness Test (back-scratch norms); ACSM's Guidelines (10th/11th ed.).
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Educational content only — not medical advice. Always consult a qualified professional for individualized guidance, especially around injury, pregnancy, or medical conditions.

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Atlas Connections

Rotator Cuff (SITS)
The four rotator cuff muscles — Supraspinatus, Infraspinatus, Teres minor, Subscapularis (SITS) — that rotate and stabilize the shoulder joint.
Shoulder / Arm Range of MotionClosely related
Arm flexion 135°, shoulder adduction 50°, shoulder hyperextension 45°, shoulder abduction 90–180°.
Flexibility Test Norms & InterpretationClosely related
Flexibility is joint-specific, so norms are tied to a specific test (e.g., sit-and-reach) and stratified by age and sex — and "more" is not always "better."
Goniometry & Range-of-Motion MeasurementClosely related
Measure the actual angle a joint moves through with a goniometer (or inclinometer/app), giving an objective, joint-specific ROM in degrees to compare against normal reference values.
Sit-and-Reach Test (and Variants)Closely related
Reach forward over straight legs on a sit-and-reach box; how far past the toes you reach indexes hamstring and lower-back flexibility against age/sex norms.
Stretch: Posterior Shoulder (Behind Back)
With one arm flexed behind the back, grasp the elbow from behind with the opposite hand and pull it across the mid-line of the back.