Reference Data

Normative Reference Values

Published normative data for grip, pinch, and hand extension force — compiled as a clinical reference for occupational and physical therapists using the Splayometer.

Overview

Using Normative Data in Practice

Normative reference values support interpretation of individual patient results and inform goal setting, but should always be contextualized within each client's occupational profile and personal history.

AOTA Framework Context

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 areas including 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 that falls 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).

Scope of Available Data

Published normative databases exist primarily for:

  • Grip strength — extensive data from multiple populations, measured with the JAMAR dynamometer
  • Pinch strength — well-established norms for tip, lateral (key), and three-jaw chuck pinch
  • Finger extension and abduction force — limited published normative data; most existing research is biomechanical rather than clinical in orientation

Splayometer-Specific Norms: Device-specific normative data for the Splayometer is in active development. Until published reference ranges are available, clinicians should emphasize within-patient serial comparison — tracking change over time for the individual — rather than comparison to population norms. See the positioning note in the Standard Use Procedures for guidance on replicating test conditions across sessions.

Interpreting Reference Values

  • Values represent means from healthy, non-clinical populations unless otherwise noted; standard deviations are reported in primary sources
  • Dominant vs. non-dominant: the dominant hand is typically 5–10% stronger; this difference is reduced in highly skilled bilateral workers
  • Age effect: grip and pinch strength peak in the third and fourth decades and decline progressively thereafter
  • Sex differences: females on average produce approximately 55–65% of male grip force at comparable ages
  • Measurement instrument matters: values from one dynamometer model should not be directly compared to values from a different instrument without cross-calibration
Grip Strength

Normative Grip Strength Values

The most widely used normative dataset for grip strength in adults, measured with the JAMAR hand dynamometer at handle position II.

Source: Mathiowetz et al. (1985)
Age Group Male — Dominant (kg) Male — Non-Dominant (kg) Female — Dominant (kg) Female — Non-Dominant (kg)
20–2456.653.431.628.5
25–2957.454.033.330.0
30–3456.652.833.930.6
35–3956.052.331.328.2
40–4454.050.930.528.0
45–4951.248.427.425.4
50–5449.545.926.524.4
55–5944.041.023.222.1
60–6443.340.020.918.9
65–6939.136.019.017.2
70–7435.433.016.615.1
75+29.528.114.413.2
Values are means in kilograms measured with the JAMAR dynamometer, handle position II, standardized arm positioning. Consult the primary source for standard deviations and full sample sizes. Mathiowetz, V., et al. (1985). Archives of Physical Medicine and Rehabilitation, 66(2), 69–74.

These remain the most widely cited grip strength norms in North American occupational and physical therapy practice and are recommended by the American Society of Hand Therapists (ASHT) as a standard reference. Values were collected from a community-based sample of 310 males and 328 females with no known upper extremity pathology.

Pinch Strength

Normative Pinch Strength Values

Normative data for the three standard pinch configurations, measured with a standard pinch gauge.

Source: Mathiowetz et al. (1985)
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)
20–248.25.29.45.89.55.7
25–348.55.59.56.19.66.1
35–448.35.29.35.99.45.9
45–548.04.69.05.59.15.5
55–646.94.18.14.98.14.9
65–746.33.57.04.47.54.2
Dominant hand values shown (means in kg). Lateral pinch = key pinch (thumb pad against lateral aspect of index finger). Three-jaw chuck = palmar (three-point) pinch. Consult primary source for full data and SDs. Mathiowetz, V., et al. (1985). Archives of Physical Medicine and Rehabilitation, 66(2), 69–74.
Finger Extension & Abduction

Finger Extension & Abduction Force

Published normative data for isolated finger extension and abduction force is more limited than for grip and pinch. Below is a summary of available evidence and its clinical relevance.

State of the Evidence

Finger extension and abduction strength has received substantial attention in biomechanics research but has not yet been as systematically normed for clinical populations as grip and pinch. Key findings from the published literature include:

  • Extension force is substantially less than grip: Individual finger extension force typically ranges from approximately 10–30% of total grip force, depending on the digit, test configuration, and population (Li et al., 1998; Zatsiorsky et al., 2000).
  • The index and middle fingers are typically strongest: In healthy adults, the index (D2) and middle (D3) fingers produce greater extension force than the ring (D4) and little (D5) fingers (Li et al., 1998).
  • Inter-finger dependence: Fingers do not operate independently — activation of one finger produces force in adjacent fingers. This "enslaving" effect is relevant to inter-digit abduction testing (Zatsiorsky et al., 2000).
  • Dorsal interosseous force: Interosseous muscle function (abduction) is sensitive to intrinsic muscle pathology and is reduced in conditions such as ulnar nerve palsy and early rheumatoid arthritis (Brorsson et al., 2009; Nordenskiöld & Grimby, 1993).
  • Sex and age effects: Extension and abduction forces show sex differences and age-related decline patterns similar to grip, but the magnitude of decline may differ by digit (Li et al., 1998).

Individual Finger Extension

Values from healthy adult populations; based on biomechanics laboratory studies using force transducers in standardized hand positions.

Index (D2) — Approximate mean, adults ~18–28 N
Middle (D3) — Approximate mean, adults ~16–26 N
Ring (D4) — Approximate mean, adults ~10–18 N
Little (D5) — Approximate mean, adults ~8–14 N

Values are approximate ranges from Li et al. (1998) and related literature. Healthy adults, mixed sex. Not intended as definitive clinical norms — consult primary sources.

Finger Abduction (Dorsal Interosseous)

Published data for isolated finger abduction force; primarily from biomechanics and rheumatology research contexts.

D2 abduction (index from middle) — Adults ~25–45 N
D3 abduction (middle from ring) — Adults ~20–38 N
D4 abduction (ring from little) — Adults ~15–28 N
Reduction in RA (estimated) ~30–50% below healthy

Approximate ranges; values vary considerably by method. Brorsson et al. (2009); Nordenskiöld & Grimby (1993). Splayometer-specific norms in development.

Until device-specific norms are published, the most clinically meaningful use of Splayometer data is within-patient serial tracking. Establish a baseline measurement at the first session, replicate test conditions at each subsequent session, and document change over time as the primary outcome indicator. Refer to the Standard Use Procedures for positioning protocols that support reliable serial comparison.

Clinical Interpretation

Applying Reference Values in Practice

Normative data should be applied with appropriate clinical judgment, contextual awareness, and sensitivity to individual variation.

Bilateral Comparison

In the absence of population norms specific to a measurement configuration, the contralateral (unaffected) hand provides a practical within-person reference standard. A commonly cited heuristic is that the dominant hand should be 5–10% stronger than the non-dominant hand; values outside this range may warrant further investigation. However, this relationship varies considerably across individuals and should not be applied rigidly.

Serial Change vs. Population Comparison

A clinically meaningful change is generally defined as a difference that exceeds the measurement error of the instrument. For grip dynamometry, the minimal detectable change (MDC) is approximately 3–5 kg (Mathiowetz et al., 1984). Splayometer-specific MDC values will be established as device-specific validity data are published. In the interim, changes greater than 10–15% from baseline across consistent test conditions are likely to reflect true change rather than measurement variability.

Dominant Hand Advantage

5–10%

Typical grip strength advantage of the dominant hand over the non-dominant hand in healthy adults (Mathiowetz et al., 1985).

Extension vs. Grip

10–30%

Approximate range of individual finger extension force as a percentage of total grip force in healthy adults (Li et al., 1998).

Peak Decade for Hand Strength

Ages 25–39

Grip and pinch strength peak in the late 20s to late 30s and decline progressively thereafter, with notable decline after age 55 (Mathiowetz et al., 1985).

References

Bibliography

Sources for the normative data and clinical context presented on this page.

  1. 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
  2. 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
  3. 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
  4. 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.
  5. 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
  6. 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
  7. 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
Protocols

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Follow our step-by-step standard use procedures for reliable, reproducible Splayometer measurements across all test configurations.