Body Composition
As of 2026-04-24
How Flexibility Score Calculator works
Methodology for the Flexibility Score Calculator: formulas, coefficients, data sources, assumptions, and known limitations.
Scope
Estimates a flexibility percentile and rating from a sit-and-reach test, adjusted for age and sex.
Formula
percentile = lookup(score_cm, age_band, sex) against ACSM sit-and-reach norms.
Coefficients
| Parameter | Value | Note |
|---|---|---|
| Test | Standard sit-and-reach (box at 26 cm feet line) |
Data sources
- American College of Sports Medicine. ACSM's Guidelines for Exercise Testing and Prescription, 11th ed. Wolters Kluwer, 2021. — Source of the sit-and-reach percentile tables used in the tool.
- Canadian Society for Exercise Physiology. Canadian Physical Activity, Fitness & Lifestyle Approach (CPAFLA) Reference Manual, 3rd ed. 2003. — Secondary set of sit-and-reach norms used as a cross-check.
- Ayala F, Sainz de Baranda P, De Ste Croix M, Santonja F. Reproducibility and criterion-related validity of the sit and reach test and toe touch test for estimating hamstring flexibility in recreationally active young adults. Phys Ther Sport. 2012;13(4):219-226. — PMID 23068896. Validation paper for the sit-and-reach protocol.
Assumptions
- Test administered after a 5–10 minute warmup; knees flat.
Approximation range
Sit-and-reach reflects posterior-chain flexibility (hamstrings, lumbar) and does not generalize to shoulder or ankle mobility.
Limitations
- Many mobility limitations are not detected by sit-and-reach; use sport-specific screens as well.
Reproducibility
Male, 30, score 30 cm: lookup returns ~60th percentile, rating 'Above Average'.
Change log
- 2026-04-24: methodology page first published.
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