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Individual finger strength: are the ulnar digits "powerful"?
Joy C MacDermid1, Adrian Lee, Robert S Richards
1School of Rehabilitation Science, McMaster University Hamilton, Ontario, Canada. macderj@mcmaster.ca
Summary
This study shows a reliable method to measure individual finger strength, revealing a consistent pattern in how fingers contribute to overall grip strength, influenced by body size.
Area of Science:
- Biomechanics
- Human Physiology
- Hand Strength Analysis
Background:
- Assessing grip strength is crucial in clinical and research settings.
- Understanding individual finger contributions to grip is not well-established.
- Existing methods may not accurately capture nuanced finger strength contributions.
Purpose of the Study:
- To determine the test-retest reliability of a novel grip device.
- To quantify the contribution of each finger to maximal grip strength.
- To describe the typical pattern of finger contribution in healthy individuals.
Main Methods:
- Employed a grip device measuring individual finger force contributions.
- Recruited subjects without hand pathology for testing.
- Subjects performed repeated maximal grip efforts across two sessions (2-7 days apart).
- Calculated Intraclass correlation coefficients (ICCs) for reliability.
Main Results:
- High test-retest reliability (ICC > 0.75) was found for most (8/10) strength measures.
- Finger contributions to grip strength were approximately: index (25%), middle (35%), ring (25%), and small (14%).
- Grip and individual finger strengths showed high correlations; body size and finger length showed moderate correlations.
Conclusions:
- A predictable pattern exists for individual finger contributions to grip strength.
- This pattern is partially influenced by anthropometric measures like body size.
- The ulnar side of the hand contributes less to overall grip strength (approx. 40%).
- Further exploration of the clinical utility of finger strength measures is warranted.