Practical Equivalence Despite Statistical Differences: A Noninferiority Analysis of Repeated Countermovement Jump...

Area of Science:

• Sports Science
• Exercise Physiology
• Neuromuscular Performance

Background:

• The countermovement jump (CMJ) is a key metric for assessing neuromuscular performance.
• Understanding the limits of CMJ testing within a single session is crucial for accurate monitoring.
• Previous research has not definitively established the optimal number of CMJ series to avoid performance degradation.

Purpose of the Study:

• To determine the maximum number of countermovement jump (CMJ) series that can be performed without significantly altering performance.
• To compare different jump-height calculation methods (flight-time vs. impulse-momentum) and data-handling strategies.
• To optimize reliable and practically relevant CMJ performance assessment protocols.

Main Methods:

• 103 healthy adults completed 9 series of 3 CMJs with 3-minute rests between series.
• Jump height was measured using flight-time and impulse-momentum methods.
• Data were analyzed using mean, mean of the 2 highest, and highest jump values, with equivalence testing against baseline.

Main Results:

• Significant time effects impacting performance were observed for both measurement methods.
• Statistically significant reductions in jump height occurred from the 3rd or 4th series onwards, depending on the analysis method.
• Certain early series (e.g., 2-4) were found to be equivalent to baseline, indicating minimal performance alteration.

Conclusions:

• Averaging multiple CMJs enhances measurement accuracy and sensitivity.
• To prevent performance bias, limit testing to a maximum of 6 series of 3 CMJs per session.
• Interpreting performance changes requires comparison to baseline variability to distinguish statistical significance from practical relevance.