Finger and Hand Extension & Abduction Reference Values
A clinician quick-reference for interpreting Splayometer measurements while device-specific norms are in development.
Scope of available data
Published norms exist for grip and pinch (Mathiowetz 1985). Finger extension and abduction data is more limited and largely from biomechanics research, not clinical norming. Splayometer-specific norms are in active development.
Interpreting these values
- Values are means from healthy populations; consult primary sources for SDs.
- Dominant hand is typically 5–10% stronger than non-dominant.
- Strength peaks in the late 20s–30s and declines progressively thereafter.
- Different instruments aren't directly comparable without cross-calibration.
Recommended use
Until device-specific norms are published, prefer within-patient serial tracking: establish a baseline at session 1, replicate test conditions at each follow-up, and document change over time as the primary outcome.
Reference Values
Approximate ranges for individual finger extension, isolated finger abduction, and whole-hand spread, drawn from biomechanics and rheumatology literature.
Published normative data for finger extension and abduction is limited. Ranges below come from biomechanics literature, not clinical norming comparable to Mathiowetz grip and pinch. Prefer within-patient serial tracking over direct comparison.
Individual Finger Extension
Approximate adult ranges, mixed sex; standardized hand position, force-transducer measurement.
Synthesized from Li et al. (1998) and related biomechanics literature; original units Newtons. Consult primary sources for SDs and methods.
Finger Abduction (Dorsal Interosseous)
Isolated finger abduction force; ranges drawn from biomechanics and rheumatology contexts.
Brorsson et al. (2009); Nordenskiöld & Grimby (1993). Source data in Newtons.
Whole-Hand Spread (Multifinger Abduction)
Cumulative four-finger abduction and adduction force — applicable to hand-loop measurement.
Pataky, Latash & Zatsiorsky (2008), n = 21 (12 F / 9 M). Used four independent transducers; hand-loop biomechanics differ — treat as orientation, not threshold.
Evidence-based context
- Extension is a fraction of grip: individual finger extension is ~10–30% of total grip force (Li 1998).
- Index and middle are strongest: D2 and D3 produce greater extension force than D4 and D5 (Li 1998).
- Inter-finger dependence ("enslaving"): activating one finger produces force in adjacent fingers (Zatsiorsky 2000).
- Sensitive to intrinsic muscle pathology: abduction declines with ulnar nerve palsy and early RA (Brorsson 2009).
- Whole-hand spread is its own metric: multifinger ab/adduction force is not predictable from single-finger strengths (Pataky 2008).
- Sex and age effects: pattern parallels grip — peak in late 20s–30s, progressive decline thereafter (Li 1998).
Recommended clinical application
Establish a baseline at session 1, replicate test conditions at each follow-up, and track change over time as the primary outcome. No Splayometer-specific minimal detectable change (MDC) has been published — interpret session-to-session variation against your own setup repeatability, not a fixed threshold. For context, grip dynamometry MDC is ~3–5 kg (Mathiowetz 1984); no equivalent value exists for finger extension or abduction.
Comparator Norms & Framework
Established normative datasets and clinical frameworks for context. Click any section to expand.
The most widely cited grip strength norms in North American hand therapy and rehabilitation. Recommended by the American Society of Hand Therapists (ASHT) as a standard reference. Sample: 310 males and 328 females with no known upper extremity pathology.
| Age Group | Male — Dominant (kg) | Male — Non-Dominant (kg) | Female — Dominant (kg) | Female — Non-Dominant (kg) |
|---|---|---|---|---|
| 20–24 | 56.6 | 53.4 | 31.6 | 28.5 |
| 25–29 | 57.4 | 54.0 | 33.3 | 30.0 |
| 30–34 | 56.6 | 52.8 | 33.9 | 30.6 |
| 35–39 | 56.0 | 52.3 | 31.3 | 28.2 |
| 40–44 | 54.0 | 50.9 | 30.5 | 28.0 |
| 45–49 | 51.2 | 48.4 | 27.4 | 25.4 |
| 50–54 | 49.5 | 45.9 | 26.5 | 24.4 |
| 55–59 | 44.0 | 41.0 | 23.2 | 22.1 |
| 60–64 | 43.3 | 40.0 | 20.9 | 18.9 |
| 65–69 | 39.1 | 36.0 | 19.0 | 17.2 |
| 70–74 | 35.4 | 33.0 | 16.6 | 15.1 |
| 75+ | 29.5 | 28.1 | 14.4 | 13.2 |
Normative data for the three standard pinch configurations, measured with a standard pinch gauge. Dominant hand values shown.
| Age Group | Tip Pinch — Male (kg) | Tip Pinch — Female (kg) | Lateral Pinch — Male (kg) | Lateral Pinch — Female (kg) | 3-Jaw Chuck — Male (kg) | 3-Jaw Chuck — Female (kg) |
|---|---|---|---|---|---|---|
| 20–24 | 8.2 | 5.2 | 9.4 | 5.8 | 9.5 | 5.7 |
| 25–34 | 8.5 | 5.5 | 9.5 | 6.1 | 9.6 | 6.1 |
| 35–44 | 8.3 | 5.2 | 9.3 | 5.9 | 9.4 | 5.9 |
| 45–54 | 8.0 | 4.6 | 9.0 | 5.5 | 9.1 | 5.5 |
| 55–64 | 6.9 | 4.1 | 8.1 | 4.9 | 8.1 | 4.9 |
| 65–74 | 6.3 | 3.5 | 7.0 | 4.4 | 7.5 | 4.2 |
Within the Occupational Therapy Practice Framework: Domain and Process (4th ed.; AOTA, 2020), hand strength norms are most relevant to the evaluation of client factors — specifically neuromusculoskeletal and movement-related body functions, including muscle power functions. These body functions underlie performance skills (motor skills) and ultimately support occupational performance across ADLs, work, and leisure.
The OTPF-4 emphasizes that assessment of client factors must always be considered in relation to the client's occupational profile and context. A grip strength value below population norms may or may not be functionally limiting for a given individual, and an above-norm value does not guarantee full occupational participation. Normative data is one input among many in a holistic evaluation (AOTA, 2020).
Bibliography
Sources for the values, framework context, and clinical guidance presented on this page.
- American Occupational Therapy Association. (2020). Occupational therapy practice framework: Domain and process (4th ed.). American Journal of Occupational Therapy, 74(Suppl. 2), 7412410010. https://doi.org/10.5014/ajot.2020.74S2001
- Brorsson, S., Nilsdotter, A., Thorstensson, C., & Hillgren, A. (2009). Does finger extension force and grip strength differ between groups of patients with different ulnar drift in rheumatoid arthritis? A pilot study. Disability and Rehabilitation, 31(22), 1879–1885. https://doi.org/10.1080/09638280902750330
- Li, Z. M., Latash, M. L., & Zatsiorsky, V. M. (1998). Force sharing among fingers as a model of the redundancy problem. Experimental Brain Research, 119(3), 276–286. https://doi.org/10.1007/s002210050343
- Mathiowetz, V., Kashman, N., Volland, G., Weber, K., Dowe, M., & Rogers, S. (1985). Grip and pinch strength: Normative data for adults. Archives of Physical Medicine and Rehabilitation, 66(2), 69–74.
- Mathiowetz, V., Weber, K., Volland, G., & Kashman, N. (1984). Reliability and validity of grip and pinch strength evaluations. Journal of Hand Surgery, 9(2), 222–226. https://doi.org/10.1016/S0363-5023(84)80146-X
- Nordenskiöld, U. M., & Grimby, G. (1993). Grip force in patients with rheumatoid arthritis and fibromyalgia and in healthy subjects: A study with the Grippit instrument. Scandinavian Journal of Rheumatology, 22(1), 14–19. https://doi.org/10.3109/03009749309099257
- Pataky, T. C., Latash, M. L., & Zatsiorsky, V. M. (2008). Multifinger ab- and adduction strength and coordination. Journal of Hand Therapy, 21(4), 377–385. https://doi.org/10.1197/j.jht.2008.02.002
- Zatsiorsky, V. M., Li, Z. M., & Latash, M. L. (2000). Enslaving effects in multi-finger force production. Experimental Brain Research, 131(2), 187–195. https://doi.org/10.1007/s002219900261
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