One of the Core Engines Powering Jefit’s New Progressive Overload System

Jefit’s new Progressive Overload (PO) System is powered by several intelligence engines working together:

Load Progression Engine (this post)
Strength Monitoring
Stimulus Volume Engine
Movement Pattern Balance Engine
North Star Progress Index (NSPI)
Mesocycle Engine (coming soon)

Each engine covers a different dimension of progress.
The Load Progression Engine is the one you feel every session — the system that decides your next weights and reps based on how you’re actually performing.

When you finish a workout, the engine quietly analyzes your full session to determine whether you’ve earned progression next time.

You do the heavy lifting.
We handle the thinking.

_{What the Load Progression Engine Actually Does
How Jefit Understands Your Strength
1. Effective Working Set Quality
2. Hard-Set Equivalent (HSE) Contribution
3. Effort & Fatigue Pattern Recognition
4. Short-Term Trend Analysis
5. Week-to-Date Stimulus & Recovery
6. Your Goal & Experience Level
How Jefit Determines Your Rep Range
When Progression Happens
Primary Lifts
Accessory Lifts
The Readiness Checklist Behind the Scenes
Personalized, Not Pre-Scripted
A Final Note: More Power, Same Simplicity}

What the Load Progression Engine Actually Does

After each workout, the engine asks a single question:

Based on today’s performance (and this week’s training), are you ready to progress?

To answer that, Jefit evaluates:

quality and stability of your working sets
effort inferred from rep patterns
short-term strength trend
your week-to-date stimulus (HSE load)
your goal (strength, hypertrophy, cutting, power, maintenance)
exercise role (primary or accessory)
your experience level
your current training phase

You train and log.
The engine interprets the data and updates your next session automatically.

How Jefit Understands Your Strength

(No formulas for you, no extra work — just smarter recommendations)

Instead of simple weight × reps formulas, Jefit builds a multi-signal strength profile using several meaningful indicators.

1. Effective Working Set Quality

The engine identifies which sets represent your true performance — filtering out warm-ups and inconsistent sets.

2. Hard-Set Equivalent (HSE) Contribution

Each set is converted into an HSE value based on:

EMG-informed muscle activation
load difficulty
how hard the set was pushed
primary vs accessory role

This tells the system how meaningful each set was.

3. Effort & Fatigue Pattern Recognition

Stable rep output → readiness.
Sharp rep drop-off → fatigue → hold progression.

4. Short-Term Trend Analysis

Today’s best performance is compared to recent sessions to detect:

improvement
stagnation
temporary fatigue

5. Week-to-Date Stimulus & Recovery

Your total HSE load across the week helps determine whether a weight increase is appropriate.

6. Your Goal & Experience Level

Each training goal uses different intensity and progression expectations.

This creates a detailed, individualized readiness picture — far beyond any single-set estimate.

A Clear Note About Technique

Jefit does not monitor your form visually.
The system assumes you’re lifting with clean, controlled technique — the same assumption every validated strength model uses.

Your performance numbers only make sense when technique stays consistent.

If your rep pattern is unusually inconsistent, the engine might delay progression — not because it “detects form,” but because instability often signals fatigue or insufficient stability.

This keeps your progress sustainable.

🧬 How Jefit Determines Your Rep Range

(Dynamic, adaptive, and deeply personalized — never static rules)

Your rep range is not predetermined or template-based.
It’s dynamically chosen using a combination of factors unique to you:

your training goal
your experience level
exercise role (primary vs accessory)
movement pattern type
your weekly training phase (foundation, intensification, peak, deload — coming in Stage 2)
your performance trend
equipment constraints (dumbbells, pins, plates)
your weekly HSE load and fatigue

All these variables interact to choose your rep range for this exercise, at this moment in your training.

This produces thousands of possible rep-range setups, all personalized.
Two users on the same plan may have completely different ranges — and your own ranges may change over time as the engine adapts.

Your rep range forms your progression window:
climb → reach the top → the engine bumps weight → restart lower → climb again.

📈 When Progression Happens

Progression is role-specific:

Primary Lifts

(squat, hinge, vertical/horizontal push/pull)

You progress when:

you reach the top of the rep range
your rep pattern is stable and controlled
your effort falls in an optimal zone
weekly HSE load supports a jump
your recent trend confirms readiness

Typical increases fall in the ~2.5–5% range depending on equipment.

Accessory Lifts

You progress when:

most sets hit the upper rep range
rep stability is solid
your weekly stimulus is balanced

Accessory jumps are intentionally smaller.

The Readiness Checklist Behind the Scenes

Before progression happens, your session passes through several logic layers:

Factor	What It Represents
Working Set Quality	Stability/consistency of your reps
HSE Stimulus	How meaningful your sets were
Effort Signal	Inferred intensity from rep pattern
Short-Term Trend	Today vs recent sessions
Weekly Load Fit	Whether your HSE load supports a jump
Goal Logic	Strength vs hypertrophy vs maintenance behavior
Equipment Reality	Matching jumps to real weight increments

Personalized, Not Pre-Scripted

Nothing inside the PO System is static.

Two users on the same plan may:

progress at different speeds
receive different weight jumps
earn progression at different times
have different rep ranges
accumulate different volumes

Because the engine adapts to their performance, their goals, and their training history.

This is true personalization — not generic templates.

A Final Note: More Power, Same Simplicity

The Load Progression Engine is built on years of Jefit development, exercise science modeling, and long-term training data — but you don’t need to change anything in how you use the app.

You train and log exactly as you always have.
Jefit’s PO Engine uses that same data to make your sessions smarter, more intentional, and more productive — automatically.

The system does the heavy thinking.
You get smoother progression, clearer targets, and better results with the same effort.

Author
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Ying Lin

The Science Behind Jefit’s Load Progression Engine