Polarized Training Calculator
Analyse your weekly training distribution and see if you follow the 80/20 polarized model.
Input Guide
How each input affects your training distribution analysis.
Input Mode
radioZone Mode: manually assign each session to Zone 1, 2, or 3. Pace Mode: enter average pace per session and let the calculator classify using your LT thresholds.
Options
Use Zone Mode if you train by heart rate or RPE. Use Pace Mode if you track GPS pace data.
Session Duration
numberTotal duration of each session in minutes. This is the primary input for calculating zone distribution percentages.
Options
Include warm-up and cool-down time — the full session, not just the main set.
Zone Assignment (Zone Mode)
selectSeiler 3-zone classification: Z1 = below LT1 (easy/conversational), Z2 = between LT1 and LT2 (moderate/tempo), Z3 = above LT2 (hard/intervals).
Options
If a session has mixed zones, assign the zone where you spent the most time.
LT1 & LT2 Paces (Pace Mode)
timeYour aerobic (LT1) and anaerobic (LT2) threshold paces in min:sec per km. LT1 is typically 25% slower than LT2. Use our Lactate Threshold Calculator if you need to estimate these.
Options
A half-marathon effort approximates LT2 pace. LT1 is roughly your comfortable "all day" pace.
Analyse Your Training Intensity Distribution with Seiler’s 3-Zone Model
Research by Stephen Seiler shows that elite endurance athletes spend roughly 80% of their training at low intensity and 20% at high intensity, with minimal time in the moderate "grey zone." This calculator analyses your weekly training sessions and classifies your distribution as polarized, pyramidal, threshold, or high-intensity — providing a Polarization Index, 80/20 Score, and actionable recommendations.
What Is a Polarized Training Distribution Calculator?
This calculator takes your weekly training sessions — each with a duration and intensity zone — and computes the percentage of time spent in each of Seiler’s three zones: Zone 1 (below LT1, easy), Zone 2 (between LT1 and LT2, moderate), and Zone 3 (above LT2, hard). It then calculates the Polarization Index (Treff et al., 2017), an 80/20 Score, and classifies your distribution pattern to help you optimize your training structure.
Why Analyse Your Training Distribution?
- Identify if you spend too much time in the "grey zone" (Zone 2) — the most common training mistake
- Track your Polarization Index to quantify training structure over time
- See how close your training matches the 80/20 principle used by elite athletes
- Get a clear classification: polarized, pyramidal, threshold, or high-intensity
- Compare different training weeks to find your optimal balance
- Research-backed: based on Seiler (2010) and Stöggl & Sperlich (2014)
Who Uses a Polarized Training Calculator?
Self-coached runners auditing their training
Check whether your weekly plan truly follows the 80/20 rule or if you’re spending too much time at moderate effort.
Coaches designing training blocks
Verify that prescribed training weeks achieve the intended polarized or pyramidal distribution for each athlete.
Marathon and ultra runners in base phase
Ensure high-volume training weeks maintain a strongly polarized structure to build aerobic capacity without overtraining.
Athletes returning from injury
Confirm that return-to-running plans keep Zone 2 and Zone 3 minimal while building back aerobic fitness in Zone 1.
Under the Hood
The mathematical models behind the distribution analysis.
Zone Distribution
For each zone k ∈ {1, 2, 3}: Pₖ = (Σ dᵢ for sessions in zone k) / T_total × 100. Distribution is calculated by total time, not session count.
Polarization Index
PI = log₁₀(T₁ × T₃ / T₂²), where Tₖ = total minutes in zone k. When T₂ = 0, a floor of 1 minute is used. When T₁ or T₃ = 0, PI = 0. Based on Treff et al. (2017).
80/20 Score
Score = max(0, 100 − |P₁ − 80| − |P₃ − 20|). Perfect 100 when exactly 80% easy and 20% hard. This is a simplified metric — not from the literature.
Classification Rules
Polarized: Z1 ≥ 75%, Z2 ≤ 10%, Z3 ≥ 15%. Pyramidal: Z1 ≥ 70%, Z2 10–20%, Z3 < 15%. Threshold: Z1 < 70% or Z2 > 20%. High-Intensity: Z1 < 50% and Z3 ≥ 35%.
Privacy
All calculations run entirely in your browser. Your training data is never transmitted to any server.
Example Scenarios
Real training weeks and their classification from the calculator.
Elite Polarized Week (7 sessions)
5 easy runs (320 min Z1), 1 tempo (40 min Z2), 1 interval session (30 min Z3). Classification: Polarized. PI ≈ 0.78. 80/20 Score ≈ 86.
390 min · 82/10/8% · PI 0.78 · Score 86
Threshold-Heavy Week (6 sessions)
3 easy runs (60 min Z1), 3 tempo sessions (155 min Z2), 1 interval (20 min Z3). Classification: Threshold. PI ≈ −1.30. 80/20 Score ≈ 22.
235 min · 26/66/9% · PI −1.30 · Score 22
Beginner 3-Day Plan
2 easy runs (60 min Z1), 1 steady run (25 min Z2). Classification: Pyramidal. PI = 0. 80/20 Score ≈ 51.
85 min · 71/29/0% · PI 0 · Score 51
Research & References
The polarized training model in this calculator is informed by the following peer-reviewed research.
- Seiler, S. (2010). What is best practice for training intensity and duration distribution in endurance athletes? International Journal of Sports Physiology and Performance, 5(3), 276–291.
- Stöggl, T. & Sperlich, B. (2014). Polarized training has greater impact on key endurance variables than threshold, high-intensity, or high-volume training. Frontiers in Physiology, 5, 33.
- Treff, G. et al. (2017). Methods for quantifying training load in endurance sports. International Journal of Sports Physiology and Performance, 12(S2), 142–149.
- Seiler, S. & Kjerland, G.Ø. (2006). Quantifying training intensity distribution in elite endurance athletes. Scandinavian Journal of Medicine & Science in Sports, 16(1), 49–56.
- Muñoz, I. et al. (2014). Does polarized training improve performance in recreational runners? International Journal of Sports Physiology and Performance, 9(2), 265–272.
Frequently Asked Questions
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