The Shape System
Every training week has a shape: a set of multipliers that control how distance is distributed across your run days. The long run is the anchor at 100%, and every other run is a percentage of that distance.
For example, if your long run is 10 miles and a Tuesday easy run has a load of 45%, that run will be 4.5 miles. The multipliers are pure ratios, so they work identically for a plan in kilometers, a 16 km long run puts that same easy run at 7.2 km.
Example Week (10-mile long run)
| Day | Type | Load % | Distance |
|---|---|---|---|
| Monday | Easy | 45% | 4.5 mi |
| Wednesday | Tempo | 50% | 5.0 mi |
| Thursday | Easy | 40% | 4.0 mi |
| Friday | MLR | 65% | 6.5 mi |
| Sunday | Long Run | 100% | 10.0 mi |
Why Multipliers?
Using multipliers instead of fixed distances guarantees a critical coaching principle: easy runs are always shorter than your medium-long run, which is always shorter than your long run. This hierarchy holds by construction. No post-processing corrections needed.
As your long run distance increases over the course of your plan, every other run scales proportionally. This creates smooth, progressive overload without sudden jumps in any single workout.
Default Multiplier Ranges
Pheidi generates default multipliers based on your training phase, experience level, and race distance. Here's how the ranges break down:
Easy Run Multipliers
| Beginner | Intermediate | Advanced | |
|---|---|---|---|
| Base | 45 to 55% | 40 to 50% | 38 to 48% |
| Build | 40 to 52% | 38 to 48% | 35 to 45% |
| Peak | 38 to 50% | 35 to 45% | 32 to 42% |
| Taper | 35 to 45% | ||
Beginners get a flatter shape (higher easy multipliers) for more even volume distribution. Advanced runners are more polarized, the long run dominates.
Other Workout Multipliers
| Type | Range | Notes |
|---|---|---|
| Long Run | 100% | Always the anchor |
| Medium-Long Run | 60 to 70% | Based on race distance and experience |
| Quality (Tempo, Intervals) | 40 to 50% | Build: 50/45/40% · Peak: 50/50/45% (Beg/Int/Adv) |
MLR Proximity Adjustment
If your medium-long run falls within 2 days of the long run, its multiplier is automatically reduced by 10% to allow adequate recovery between the two longest runs of the week.
Editing Load Percentages
On the Overview tab, a workout cell shows the type and the distance. Open that cell's menu and choose Edit. The edit sheet has a Load slider for easy, recovery, medium-long, and quality runs, from 10% to 100% in steps of 5, as a share of that week's long run. When you let go of the slider, the distance on the sheet updates to match. Save writes the new multiplier onto that workout alone. The long run stays the 100% anchor and has no slider.
This is useful for fine-tuning individual runs, for example, trimming a mid-week run during a busy work week, or bumping up an easy day if you're feeling strong.
Per-Type Defaults
A single cell edit changes one workout. To shift a whole workout type everywhere, use Workout Load Defaults in Settings: one slider per type, each a percentage of the long run. An override there replaces the default multiplier for every run of that type, in newly generated plans as well as in weeks that get reshuffled.
Some coaching styles set these for you. The Cumulative-fatigue style is the clearest example: it raises easy runs to 55% and the medium-long run to 75%, which is what makes its week flatter and leaves the long run a smaller share of a bigger total.
Injury and Vacation
Injuries and vacations also work through the shape system, scaling multipliers up or down to adjust your volume. See the dedicated pages for details:
Key Takeaway
The load percentage is the single number that controls how far you run on any given day. distance = long run distance × load %. Everything else, weekly volume, the "hump" shape of mid-week intensity, emerges from these percentages.
Load distribution lives inside the Pheidi app, sign in to tune your week.
Research & evidence
Science behind this feature from pheidi.training.
- Running Training Plan: The Complete Guide Pillar hub linking 48+ deeper dives, start here for the full picture.
- Polarized Training: The Gray Zone Problem Why most runners train too hard on easy days and too easy on hard days.
- The 80/20 Polarized Training Rule Dr. Stephen Seiler's session-count distribution across elite endurance sports.
- The Gray Zone Training Mistake Zone 2 costs fatigue without the adaptations of Zone 3.
- Measuring 80/20 Training Session count vs time-in-zone and why the metric changes the answer.
- The Weekly Volume Sweet Spot Injury rates minimize around 30 to 50 km/week for most runners.
See also
- How Plan Generation Works How Pheidi builds your personalized marathon training plan: periodization, phase splits, shape-based load distribution, taper math, and base building.
- How Adaptive Progression Works How Pheidi increases your training volume safely: volume-aware increase rates, 3-up-1-down recovery weeks, and protection against rapid mileage spikes.
- How Pacing Guidance Works How Pheidi calculates your training paces: VDOT pace zones, Borg RPE descriptions, and heart rate alternatives for every workout type.