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Individualized Z-Score Classification of Jump Load and Its Association With Countermovement Jump Performance
Gabriel J Sanders1, James Stampley2, Ben Parker1
1Department of Exercise Science, University of Cincinnati, Cincinnati, Ohio.
Journal of Strength and Conditioning Research
|June 16, 2026
Summary
Individualized workload monitoring using z-scores did not predict next-day countermovement jump (CMJ) performance in female volleyball players. Typical in-season training variations did not significantly impact neuromuscular status detectable by CMJ testing.
Area of Science:
- Sports Science
- Exercise Physiology
- Biomechanics
Background:
- Countermovement jump (CMJ) assesses neuromuscular performance.
- The impact of daily workload fluctuations on CMJ performance in volleyball is not well understood.
- Individualized monitoring may reveal subtle training load effects.
Purpose of the Study:
- To investigate if individualized z-score classifications of daily workload predict next-day CMJ performance in NCAA Division I female volleyball athletes.
- To determine the association between deviations in player load and jump counts from typical values and subsequent CMJ outcomes.
- To analyze these associations throughout a competitive season.
Main Methods:
- Fourteen NCAA Division I female volleyball athletes were monitored over a season.
- External workloads (player load, jump counts) and CMJ performance were recorded.
- Z-scores classified daily workloads as low, moderate, or high relative to individual baselines.
Main Results:
- Z-score binning effectively differentiated workload exposure with large effect sizes for player load and jump counts.
- No significant differences or correlations were found between workload classifications and CMJ performance variables.
- CMJ performance metrics showed trivial effect sizes across all workload categories.
Conclusions:
- Individualized z-score workload classifications were not associated with next-day CMJ performance in this cohort.
- Typical in-season training load variations in female collegiate volleyball may not be sufficient to alter neuromuscular status detectable by CMJ.
- Further research may explore other performance metrics or different monitoring approaches.
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