19 sources: 1 meta-analysis, 4 narrative reviews, 1 non-randomised trial, 6 randomised controlled trials, 5 systematic reviews, 2 with design not recorded
Physical · Practice
Polarized (80/20) Training
About 80 percent easy aerobic volume and 20 percent hard across the week: one way to carry out what the review summary this entry was written from reports: that pyramidal and polarized intensity distributions outperform threshold training.
9 of 19 sources behind this entry were read from the abstract only; they are marked in the sources list.
4–6×/week
AdvancedAnywhere
Before you start
Avoid drifting into a moderate 'grey zone' every day
When to seek a professional
- Chest pain, pressure, or unusual shortness of breath during exertion
- Fainting, dizziness, or palpitations with exercise
- Known or suspected cardiovascular, metabolic, or renal disease without medical clearance
How to do it
~80% easy volume, ~20% high-intensity across the week
The research behind this entry establishes something about dose, but not these exact parameters; treat them as a practical way to apply the finding rather than as the finding itself.
Any aerobic modeExperiencedFor most adults
What the evidence says
What the sources say
This practice is one way to carry out what the sources on the concept entry (phys.cardio.intensity-distribution) studied: how endurance training intensity is distributed across a week and how training is periodized. Kenneally 2017 (systematic review, 16 studies) reports pyramidal and polarized training as more effective than threshold training for running performance, though threshold is used by some of the “best marathon runners”. Casado 2022 (systematic review, 10 articles) reports that highly trained and elite distance runners typically follow a pyramidal distribution with decreasing volume from zone 1 to zone 3, marathoners more pyramidal and 1500-m runners more polarized, and encourages a hard day-easy day approach. González-Ravé 2021 (systematic review, 9 studies) reports that highly trained swimmers follow volume and intensity distribution based on their primary event, sprint swimmers polarized or threshold and long-distance swimmers pyramidal. The full account, source by source, is on the concept entry this practice links to (phys.cardio.intensity-distribution).
Common misconceptions
- 'Every session should be hard' (most should be easy)
- MYTH: Easy days are junk miles. CORRECTION: pyramidal and polarized distributions, which place most training volume at low intensity, outperform threshold training.
What we won't claim
- No cure claims for any disease
- No guaranteed outcomes or fixed numeric results for any individual
- Does not replace prescribed medical treatment
- The exact 80/20 ratio is a guideline, not a fixed law
19 sources: 1 meta-analysis, 4 narrative reviews, 1 non-randomised trial, 6 randomised controlled trials, 5 systematic reviews, 2 with design not recorded
- Agreement
- Direction recorded for 0 of 19 sources; not yet recorded for the rest.
- The claim's outcome
- Outcome not yet recorded
- Certainty
- No source states a certainty rating.
- Authors
- Sources share authors: B. Rnnestad (first author of 3 sources); J. Conlon (first author of 2 sources); V. Issurin (first author of 3 sources); G. Haff (senior author of 2 sources); S. Ellefsen (senior author of 2 sources); V. Issurin (senior author of 3 sources).
- How the sources were read
- Some sources are based on abstracts, not full texts.
What each source measured and concluded (19)
randomised controlled trial · 2016
Conlon et al. (2016) — Periodization Strategies in Older Adults: Impact on Physical Function and Health.
- What it measured
- Physical function and health outcomes
- How it was read
- based on the abstract, not the full text
design not recorded · 2018
Manchado et al. (2018) — Effects of Two Different Training Periodization Models on Physical and Physiological Aspects of Elite Female Team Handball Players
- What it measured
- Physiological and physical handball performance factors (strength, power, sprint, VO2max, throwing velocity)
- How it was read
- based on the abstract, not the full text
randomised controlled trial · 2018
Rønnestad et al. (2018) — Block periodization of strength and endurance training is superior to traditional periodization in ice hockey players
- What it measured
- Strength (knee extension peak torque), power, and endurance (VO2max)
- How it was read
- based on the abstract, not the full text
meta-analysis · 2019
Mølmen et al. (2019) — Block periodization of endurance training – a systematic review and meta-analysis
- What it measured
- VO2max and maximal power output (Wmax); endurance performance
- How it was read
- based on the abstract, not the full text
- What the review says it includes
- Systematic review and meta-analysis
- Studies and participants, as stated
- N=20 studies (6 pooled for meta-analysis; from 2,905 screened)
systematic review · 2017
Kenneally et al. (2017) — The Effect of Periodization and Training Intensity Distribution on Middle- and Long-Distance Running Performance: A Systematic Review.
- What it measured
- Effect of training intensity distribution (pyramidal, polarized, threshold) on running performance
- How it was read
- based on the abstract, not the full text
- What the review says it includes
- Systematic review
- Studies and participants, as stated
- N=16 studies (6 observational, 3 case studies, 6 interventions, 1 review; from 493 articles)
randomised controlled trial · 2017
Conlon et al. (2017) — The efficacy of periodised resistance training on neuromuscular adaptation in older adults
- What it measured
- Neuromuscular adaptations (muscle CSA, strength, power, torque)
- How it was read
- based on the abstract, not the full text
randomised controlled trial · 2014
Bartolomei et al. (2014) — A Comparison of Traditional and Block Periodized Strength Training Programs in Trained Athletes
- What it measured
- Strength and power performance
- How it was read
- based on the abstract, not the full text
systematic review · 2021
González-Ravé et al. (2021) — Training Intensity Distribution, Training Volume, and Periodization Models in Elite Swimmers: A Systematic Review.
- What it measured
- Training intensity distribution, training volume, and periodization models
- How it was read
- based on the abstract, not the full text
- What the review says it includes
- Systematic review
- Studies and participants, as stated
- 9 studies (from 3487 identified); 3 intervention and 6 observational
randomised controlled trial · 2016
Rønnestad et al. (2016) — 5‐week block periodization increases aerobic power in elite cross‐country skiers
- What it measured
- Aerobic power indices (peak power output, power at 4 mmol/L lactate, VO2max)
- How it was read
- based on the abstract, not the full text
non-randomised trial · 2012
Painter et al. (2012) — Strength gains: block versus daily undulating periodization weight training among track and field athletes.
- What it measured
- Improvement in maximal strength and rate of force development.
- How it measured it
- 1-RM parallel squat and isometric midthigh pulls (MTPs) (objective).
- How it was read
- read in full text
randomised controlled trial · 2014
Rønnestad et al. (2014) — Block periodization of high‐intensity aerobic intervals provides superior training effects in trained cyclists
- What it measured
- Increase in VO2max, peak power output (Wmax), and power output at 2 mmol/L [la−].
- How it measured it
- VO2max (validated), Wmax (validated), power output at 2 mmol/L [la−] (validated).
- Its conclusion, in its own words
- “The present study suggests that block periodization of training provides superior adaptations to traditional organization during a 4‐week endurance training period, despite similar training volume and intensity.”
- How it was read
- read in full text
systematic review · 2025
Sahabuddin (2025) — Periode Pelatihan Fisik untuk Atlet Elit: Konsep Saat Ini dan Arah Masa Depan
- What it measured
- Enhancement of aerobic capacity and muscle strength.
- How it measured it
- VO2 max and muscle strength tests (objective).
- How it was read
- read in full text
systematic review · 2023
Galán-Rioja et al. (2023) — Training Periodization, Intensity Distribution, and Volume in Trained Cyclists: A Systematic Review.
- What it measured
- Improvement in VO2max, peak aerobic power, lactate thresholds, and ventilatory thresholds.
- How it measured it
- Objective physiological tests (e.g., VO2max tests, lactate threshold assessments).
- How it was read
- read in full text
- What the review says it includes
- Systematic review of 7 studies
- Studies and participants, as stated
- N=161 participants across 7 studies
systematic review · 2022
Casado et al. (2022) — Training Periodization, Methods, Intensity Distribution, and Volume in Highly Trained and Elite Distance Runners: A Systematic Review.
- What it measured
- Training intensity distribution (TID), volume, periodization, and methods; differences between event distances
- How it was read
- screened only, not extracted
- What the review says it includes
- Systematic review
- Studies and participants, as stated
- 10 articles included
narrative review · 2016
Issurin (2016) — Benefits and Limitations of Block Periodized Training Approaches to Athletes’ Preparation: A Review
- What it measured
- Benefits and limitations of block periodized (BP) training approaches
- How it was read
- screened only, not extracted
narrative review · 2022
Api et al. (2022) — COMPARISON OF PERIODIZATION MODELS: A CRITICAL REVIEW WITH PRACTICAL APPLICATIONS
- What it measured
- Comparison of traditional, block and undulating periodization models
- How it was read
- screened only, not extracted
design not recorded · 2010
García-pallarés et al. (2010) — Performance changes in world-class kayakers following two different training periodization models
- What it measured
- Physiological, body composition and performance changes after traditional (TP) vs block (BP) periodization
- How it was read
- screened only, not extracted
narrative review · 2018
Issurin (2018) — Biological Background of Block Periodized Endurance Training: A Review
- What it measured
- Biological/molecular background and metabolic-performance effects of block periodized endurance training
- How it was read
- screened only, not extracted
narrative review · 2010
Issurin (2010) — New Horizons for the Methodology and Physiology of Training Periodization
- What it measured
- Methodology and physiology of training periodization; limitations of traditional periodization
- How it was read
- screened only, not extracted
Key sources (19)
Every source below is shown with its study design and links to the original study. This is the audit trail.
randomised controlled trialPeriodization Strategies in Older Adults: Impact on Physical Function and Health.
design not recordedEffects of Two Different Training Periodization Models on Physical and Physiological Aspects of Elite Female Team Handball Players
randomised controlled trialBlock periodization of strength and endurance training is superior to traditional periodization in ice hockey players
meta-analysisBlock periodization of endurance training – a systematic review and meta-analysis
systematic reviewThe Effect of Periodization and Training Intensity Distribution on Middle- and Long-Distance Running Performance: A Systematic Review.
randomised controlled trialThe efficacy of periodised resistance training on neuromuscular adaptation in older adults
randomised controlled trialA Comparison of Traditional and Block Periodized Strength Training Programs in Trained Athletes
systematic reviewTraining Intensity Distribution, Training Volume, and Periodization Models in Elite Swimmers: A Systematic Review.
randomised controlled trial5‐week block periodization increases aerobic power in elite cross‐country skiers
non-randomised trialStrength gains: block versus daily undulating periodization weight training among track and field athletes.
randomised controlled trialBlock periodization of high‐intensity aerobic intervals provides superior training effects in trained cyclists
systematic reviewPeriode Pelatihan Fisik untuk Atlet Elit: Konsep Saat Ini dan Arah Masa Depan
systematic reviewTraining Periodization, Intensity Distribution, and Volume in Trained Cyclists: A Systematic Review.
systematic reviewTraining Periodization, Methods, Intensity Distribution, and Volume in Highly Trained and Elite Distance Runners: A Systematic Review.
narrative reviewBenefits and Limitations of Block Periodized Training Approaches to Athletes’ Preparation: A Review
narrative reviewCOMPARISON OF PERIODIZATION MODELS: A CRITICAL REVIEW WITH PRACTICAL APPLICATIONS
design not recordedPerformance changes in world-class kayakers following two different training periodization models
narrative reviewBiological Background of Block Periodized Endurance Training: A Review
narrative reviewNew Horizons for the Methodology and Physiology of Training Periodization
“Abstract only” means the review read that paper’s abstract, not its full text; “screened only” means it was included at re-screening and not extracted. Both stay in the trail with their DOI, because how a source was read is part of the audit.
Explore all 1,293 studies in Cardio & Endurance →
The full evidence base this focus area draws on, every study with its design and DOI.What it is for
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