The Stimulus Volume Engine

How Jefit Tracks the Quality and Balance of Your Weekly Training Workload

In strength training, volume isn’t just how many sets you do — it’s how much meaningful work your muscles actually perform.

The Stimulus Volume Engine is Jefit’s way of translating your logged workouts into a real measure of training stress and adaptation potential.
It’s part of the Progressive Overload (PO) System, powering the NSPI dashboard to help you see whether your weekly workload is on pace, balanced, and recoverable.

Table of contents

_{What the Stimulus Volume Metric Represents
How the Stimulus Volume Graph Works
How to Read the Weekly HSE Table
How Stimulus Volume Is Calculated
How to Use It
Personalized by Goal and Experience
Why It Matters
What’s Next
Explore More
North Star Progress Index Overview →
Strength Engine →
Movement Balance Engine →
In Short}

What the Stimulus Volume Metric Represents

Each time you log a working set, Jefit calculates its Hard Set Equivalent (HSE) — an EMG-informed value that estimates the true hypertrophic stimulus that set contributes.

One hard, near-failure set on a primary mover muscle equals roughly 1 HSE.
Lighter, accessory, or partial-effort sets contribute proportionally less.

Your Stimulus Volume total is the sum of all those HSEs across every muscle group for the week.
It reflects not just how much you trained — but how effectively those sets drove adaptation.

How the Stimulus Volume Graph Works

Your Stimulus Volume section displays a weekly view (Sunday–Saturday) showing how your total effective workload is accumulating through the week.

• X-axis: Days of the week (S–S).
• Trend band: The expected total HSE range — your personalized target for weekly training volume.
• Purple dots: Your actual accumulated HSE each day, updated as you train.

When your dots stay within the band, your total training load is on track.
Dots that rise above the band indicate higher-than-planned intensity or frequency — still positive in the short term, but something to keep an eye on for recovery.
Dots falling below the band show that your weekly workload is under target, often due to missed sessions or lighter effort earlier in the week.

You can visually see whether your total effective sets (HSE) are trending in sync with your plan — and make timely adjustments before the week ends.

How to Read the Weekly HSE Table

Below the graph, you’ll see a simple breakdown showing each muscle group’s progress toward its weekly target:

Muscle Group	Example Format	Meaning
Chest	12 / 12	You’ve completed all planned hard sets for the week.
Shoulders	10 / 12	You’re close to target — one more pressing or isolation session will finish the goal.
Glutes	8 / 12	Slightly under target — consider another lower-body day if recovery allows.

These numbers come directly from your exercise logs.
Each exercise contributes partial or full HSE credit to multiple muscles based on EMG weighting — so even compound lifts like squats or rows count toward several groups simultaneously.

When all muscle groups are near their targets by week’s end, your overall Stimulus Volume trend will sit comfortably inside the target band.

How Stimulus Volume Is Calculated

You don’t need to do the math — but understanding the logic helps you interpret it confidently.

Each logged working set is converted into HSE using four key inputs:

1. Muscle Involvement (EMG-based) – Determines how much each muscle is activated during the movement.
2. Load Intensity – Weights the set by relative load compared to your estimated 1RM.
3. Effort Level – Accounts for how close the set was to failure (based on rep patterns and volume consistency).
4. Exercise Role Weighting – Adjusts stimulus contribution for primary vs. accessory exercises.

All HSEs across the week are summed by muscle group, then compared to your target range — which is customized to your goal (strength, hypertrophy, power, cutting, or maintenance) and experience level.

This approach makes Jefit’s Stimulus Volume system goal-specific, evidence-based, and adaptive.

How to Use It

• Monitor your dots vs. band:
  Keep your accumulated HSE trend line within or near the shaded target band.
  It means your training load is pacing perfectly with your recovery capacity.
• Check your muscle table:
  Use the per-muscle HSE counts to balance undertrained areas before the week ends.
• Avoid chasing volume for its own sake:
  Being far above target might feel productive short-term, but consistent overshooting can build fatigue faster than adaptation.

💡 Tip: The goal isn’t to max out sets — it’s to sustain high-quality training that fits your current phase and recovery readiness.

Personalized by Goal and Experience

Your weekly target band and per-muscle HSE goals adapt automatically:

• Strength-focused users: Lower total HSE, higher intensity per set.
• Hypertrophy goals: Higher HSE accumulation, more total volume.
• Cutting or maintenance: Moderate HSE totals with greater focus on stability and recovery.

Each plan uses your recent performance to refine next week’s target automatically — a feedback loop that makes Stimulus Volume self-correcting and personalized.

Why It Matters

Stimulus Volume bridges the gap between training effort and training quality.
It shows not only whether you’re doing enough, but whether that “enough” is moving you in the right direction.

When paired with your Strength and Movement Balance metrics, it gives you a full picture of how your plan is working — showing if you’re building muscle efficiently, managing fatigue, and keeping your workload in the sweet spot.

What’s Next

Today, the Stimulus Volume view helps you monitor and adjust your weekly training pace.
In upcoming updates, Jefit will expand this into multi-week and mesocycle-level tracking, showing how your weekly HSE totals trend over time and automatically adjusting your workload curve for optimal progression.

You’ll see not just how you trained this week — but how your cumulative effort is driving your next phase of growth.

Explore More

Explore the other NSPI components:

• North Star Progress Index Overview →
• Strength Engine →
• Movement Balance Engine →

In Short

The Stimulus Volume Engine tracks how much effective work your muscles perform each week — measured through EMG-informed Hard Set Equivalents (HSE).
By keeping your workload within your personalized target band, you’ll know you’re training enough to grow — but not so much that you can’t recover.

Because progress isn’t about doing more — it’s about doing the right amount, at the right time.