Central and Peripheral Shoulder Fatigue Pre-screening Using the Sigma-Lognormal Model: A Proof of Concept

Area of Science:

• Neuromuscular Physiology
• Biomechanics
• Motor Control Theory

Background:

• Clinical detection of central and peripheral shoulder fatigue is limited, hindering effective recovery interventions.
• The Kinematic Theory of Rapid Human Movements offers a model for neuromotor impulse response using lognormal functions, applicable to pathology detection.

Purpose of the Study:

• To determine if shoulder neuromuscular fatigue can be detected using parameters from the Kinematic Theory.
• To assess the ability to discriminate between central and peripheral shoulder fatigue.
• To identify which handwriting test provides the most relevant fatigue information.

Main Methods:

• Twenty healthy participants performed fast stroke handwriting tasks on a tablet before and after induced shoulder fatigue (internal and external rotation).
• Parameters were extracted using the Sigma-Lognormal model of the Kinematic Theory.
• Statistical analyses included U-Mann-Whitney and Hotelling's T-squared tests, with Spearman correlations for parameter relationships.

Main Results:

• Statistically significant differences in central and peripheral parameters were observed post-fatigue, enabling discrimination.
• Group analysis revealed increased parameters related to motor program execution after shoulder fatigue.
• Simple stroke tests pinpointed fatigue origins, while oscillation tests showed higher sensitivity to fatigue.

Conclusions:

• The Sigma-Lognormal model provides an innovative method for detecting and discriminating central and peripheral shoulder fatigue.
• This approach has potential applications for personalized follow-up in clinical and sports settings.