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Retainable Power Index (RPI™)

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Retainable Power Index (RPI™) quantifies how well an athlete maintains performance across repeated exposures relative to their highest demonstrated output.

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Rather than asking:

• How high did performance peak?

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RPI asks:

• How well did performance hold?

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It transforms performance evaluation from isolated capability to sustained capability.

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First Principle

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If output cannot be retained, it cannot be relied on.

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Peak output represents potential.

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RPI represents usable performance.

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Because in sport, repeatable performance wins more often than isolated excellence.

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Why RPI™ Exists

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Traditional performance systems primarily evaluate:

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• Peak power
• Maximum velocity
• Highest jump
• Fastest sprint
• Best repetition

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These metrics identify an athlete’s ceiling but provide little insight into whether that performance can be reproduced.

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Training and competition instead demand:

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• Repeatability
• Stability under fatigue
• Consistent execution
• Reliable output over time

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RPI was developed to measure exactly that.

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The Questions RPI Answers

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RPI helps answer questions traditional testing cannot:

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• Can this level of output be repeated?
• How quickly does performance begin to decline?
• Is this intensity sustainable?
• Is fatigue limiting usable performance?
• Is the athlete becoming more resilient over time?

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Rather than measuring only performance capacity, RPI evaluates performance durability.

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How RPI Works

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RPI evaluates repeated performance using the athlete’s highest observed output as the reference.

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Across each exposure, the system evaluates:

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• Output retention
• Performance consistency
• Rate of decline
• Stability across efforts

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The result is a single percentage:

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RPI (%)

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which reflects how much of the athlete’s highest output was successfully retained throughout the session.

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Higher values indicate greater performance durability.

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Lower values indicate earlier performance breakdown.

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Measurement Methods

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RPI can be calculated using multiple measurement approaches.

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Technology Mode

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Uses objective performance metrics such as:

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• Velocity
• Power
• Jump height
• Force
• Time
• Other measurable outputs

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Provides the highest level of measurement precision.

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Observation Mode

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When technology is unavailable, coaches can evaluate output using structured observation.

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Current observation methods include:

• Binary (0–1)
• Ternary (0–1–2)

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These systems estimate retention using standardized performance criteria while preserving the same underlying evaluation philosophy.

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Regardless of measurement method:

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RPI always measures how well performance is retained across repeated exposures.

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RPI Interpretation

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RPI provides a performance signal, not simply a percentage.

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High RPI

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• Stable output
• Strong repeatability
• Appropriate loading
• High transfer potential

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Moderate RPI

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• Beginning performance degradation
• Fatigue accumulating
• Continued monitoring recommended

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Low RPI

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• Output is not sustainable
• Fatigue limiting performance
• Training adjustment warranted

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Interpretation always considers movement demands, measurement precision, and training context.

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Output Pattern Recognition

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RPI evaluates more than overall retention.

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It also identifies how output behaves throughout the session.

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Common retention profiles include:

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Early Drop

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Rapid decline immediately after peak output.

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Often indicates:

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• Excessive intensity
• Poor readiness
• Insufficient recovery

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Gradual Decline

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Steady reduction across repeated efforts.

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Often reflects:

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• Fatigue accumulation
• Volume exceeding current capacity

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Variable Output

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Large fluctuations between efforts.

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Often reflects:

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• Technical inconsistency
• Control limitations
• Incomplete adaptation

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Stable Retention

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Minimal variation throughout the session.

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Represents:

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• High repeatability
• Strong movement control
• Durable performance

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These patterns provide context that percentage values alone cannot.

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Session Intelligence

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Within the EVZ System, RPI contributes to a broader interpretation of session quality.

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Each session combines multiple performance indicators, including:

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• Retainable Power Index (RPI™)
• Output behavior
• EVZ compliance
• Fatigue response
• Retention profile

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Together these produce the Session Score, providing coaches with a concise assessment of overall session quality rather than relying on a single metric.

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Decision Framework

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RPI supports objective coaching decisions.

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High Retention

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Progress

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• Increase training demand
• Introduce greater exposure
• Advance loading strategy

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Moderate Retention

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Hold

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• Maintain current progression
• Continue monitoring
• Observe future trends

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Low Retention

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Adjust

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• Reduce training demand
• Modify structure
• Improve recovery
• Reassess readiness

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Longitudinal Analysis

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A single session provides information.

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Multiple sessions reveal adaptation.

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Over time RPI identifies whether an athlete is:

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Improving

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Retention capacity is increasing.

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Training adaptations are occurring.

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Stable

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Performance remains consistently repeatable.

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Current programming appears appropriate.

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Declining

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Retention is decreasing.

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Fatigue, overload, or inadequate recovery may be accumulating.

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Longitudinal analysis allows coaches to evaluate adaptation rather than isolated performance.

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Integration Within the EVZ System

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RPI serves as the foundational performance metric throughout the EVZ ecosystem.

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It contributes to:

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• Session Score
• Retention Profiles
• Diagnostic Testing
• Output Classification
• Trend Analysis
• Coach Reports
• Certified Recommendations

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Rather than replacing coaching judgment, RPI provides objective evidence to support it.

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What RPI Replaces

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RPI shifts coaching away from:

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• Peak-only evaluation
• Subjective fatigue estimates
• Guess-based progression
• Isolated performance metrics
• Spreadsheet-driven interpretation

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Instead, it provides a repeatable framework for evaluating sustainable performance.

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Core EVZ Definitions

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Retention Profile

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The characteristic pattern describing how performance is maintained, declines, or stabilizes throughout repeated exposures.

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Output Stability

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The consistency of performance across repeated efforts.

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Output Variability

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The degree of fluctuation between repeated efforts.

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Output Decay Rate

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The speed at which performance declines during repeated exposure.

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These concepts provide the framework for interpreting RPI beyond a single numerical value.

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System Philosophy

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Performance should not be judged by what an athlete can produce once.

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It should be judged by what they can reliably reproduce.

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RPI measures the durability of performance.

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High RPI reflects stable, repeatable output.

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Low RPI reflects early breakdown under repeated demand.

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The goal is not simply to produce more.

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The goal is to produce consistently.

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Important Note

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RPI is derived from proprietary retention analysis that evaluates repeated performance using structured EVZ methodologies.

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Depending on measurement method and training context, the system evaluates factors including:

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• Output retention
• Performance stability
• Fatigue response
• Retention profiles
• Longitudinal adaptation

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Interpretation is always context-dependent, recognizing that acceptable output loss varies across movements, sports, and training environments.