Repeatability and Specificity of Eccentric Force Output and the Implications for Eccentric Training Load Prescription

Area of Science:

• Sports Science
• Biomechanics
• Exercise Physiology

Background:

• Prescribing eccentric (ECC) exercise loads often relies on non-ECC specific strength measures.
• This approach may not accurately reflect an individual's tolerance or capacity for ECC exercise.

Purpose of the Study:

• To assess the repeatability and specificity of maximal accentuated-eccentric (ECC+) force output.
• To evaluate the accuracy of using non-specific strength measures for ECC+ training load prescription.

Main Methods:

• A test battery including ECC+, traditional coupled eccentric-concentric (TRAD), and isometric (ISO) conditions (ISO90, ISO120) was administered.
• Repeatability and force output differences between tasks were analyzed.

Main Results:

• The test battery demonstrated high repeatability (ICC > 0.95, CV < 5.8%).
• ECC+ force output was task-specific, differing significantly from ISO and TRAD conditions.
• Estimations of ECC+ strength using non-specific measures introduced up to 7% error.

Conclusions:

• Eccentric force production is highly specific to the task performed.
• Prescribing eccentric training loads based on isometric or concentric strength can lead to discrepancies in exercise intensity.
• An ECC-specific assessment is recommended for accurate individualized eccentric training prescription.