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Identification of feigned shoulder flexion weakness in normal subjects
Zeevi Dvir1, Yael Steinfeld-Cohen, Chava Peretz
1Department of Physical Therapy, Sackler Faculty of Medicine, Tel Aviv University, Ramat Aviv, Israel.
Summary
The difference between eccentric to concentric strength ratios (DEC) effectively identifies feigned shoulder weakness. This index accurately detected simulated injuries across various ranges of motion, aiding in diagnosing genuine effort.
Area of Science:
- Biomechanics
- Sports Medicine
- Neurology
Background:
- Assessing maximal voluntary contraction is crucial in clinical and sports settings.
- Differentiating genuine weakness from feigned effort can be challenging.
- The eccentric to concentric strength ratio (DEC) is a potential indicator of effort.
Purpose of the Study:
- To evaluate the efficacy of three test protocols in identifying feigned shoulder flexion effort using the DEC.
- To determine if the DEC index can reliably detect simulated weakness.
Main Methods:
- Seventeen healthy subjects performed maximal concentric and eccentric shoulder flexion.
- Subjects then feigned weakness, simulating a shoulder injury.
- The DEC was calculated for each condition and compared.
Main Results:
- DEC scores were significantly higher during feigned effort compared to maximal effort for both ranges of motion.
- A combination of 40 and 160 degrees/sec correctly identified 100% of feigned efforts.
- The DEC proved effective even with limited range of motion variations.
Conclusions:
- The DEC index is a reliable tool for detecting feigned shoulder flexion effort.
- Adequate velocity gradients are key to the DEC's effectiveness.
- This method allows for effort assessment even when full range of motion is compromised due to pain or instability.