Evidence & Training · Strength
Periodization Explained: Linear vs Undulating Training
What periodisation is, what meta-analyses show for strength and hypertrophy, how linear and undulating models differ, and simple ways to apply them.
Periodisation sounds like something only elite athletes need: training blocks, peaking phases and spreadsheets full of percentages. In practice, it simply means planning how training changes over time instead of repeating the same sessions indefinitely.
The evidence on periodisation is more interesting than either its fans or critics suggest. It appears to help maximal strength, especially in trained lifters, but it does not seem to matter much for muscle growth when total volume is the same.
This article explains the main models, what the research shows, and how to use periodisation without over-engineering your training.
Quick answer
Periodised training produces larger gains in maximal strength than non-periodised training, and undulating models appear to have an edge in trained lifters [1] [2].
For hypertrophy, periodisation does not appear to change results when volume is equated [2]. Use it mainly to organise strength work and to manage fatigue.
The main models
Linear periodisation moves from higher volume and lighter loads toward lower volume and heavier loads across weeks — for example, three weeks of 3×10, then 4×6, then 5×3. Undulating periodisation varies volume and load more frequently, often within the same week: a heavy day, a moderate day and a lighter, higher-rep day.
Block periodisation, common in strength sports, organises training into focused blocks (accumulation, intensification, peaking). All models share one idea: planned variation.
What the evidence says for strength
Moderate evidenceA 2017 meta-analysis of 18 studies found that periodised resistance training produced greater improvements in one-rep max than non-periodised training, with a moderate effect size. Undulating programmes were more favourable, and higher training frequency and longer study duration were associated with larger gains [1].
A 2022 meta-analysis of volume-equated studies confirmed the advantage for 1RM strength. Undulating periodisation produced greater 1RM gains than linear periodisation — but only in trained participants; in untrained participants the two were similar [2].
What the evidence says for muscle growth
Moderate evidenceIn the same 2022 analysis, muscle hypertrophy did not differ between periodised and non-periodised training, or between linear and undulating models, when volume was equated [2]. The authors suggested that periodisation's benefit for strength may relate to neural adaptations rather than muscle size.
For hypertrophy, then, the big levers remain volume, effort and progression. Periodisation is a way to schedule them, not an additional growth stimulus.
Simple ways to periodise
The simplest undulating approach is to give each main lift a heavy day and a moderate day each week. For example, a heavy squat day at 4–6 reps and a lighter day at 8–10 reps. Each day still progresses on its own.
Layer a simple block structure over that: four to six weeks of gradually increasing effort or load, followed by a lighter week, then a new block with slightly different rep targets. This builds variation and fatigue management into your plan without complex spreadsheets [3].
Common mistakes
- 1
Over-planning beyond a few weeks
Detailed plans for six months rarely survive real life. Plan the current block in detail and the next one loosely.
- 2
Expecting periodisation to accelerate muscle growth
When volume is equal, it does not appear to change hypertrophy [2]. Fix volume and effort first.
- 3
Changing everything every week
Undulation means varying load and reps within a stable structure, not random workouts. Keep the exercises consistent enough to track progress.
Practical takeaway
- 1Use periodisation mainly for strength goals.
- 2Give each main lift a heavy day and a moderate day each week.
- 3Run blocks of about 4–6 weeks with gradually increasing effort or load.
- 4End blocks with a lighter week when fatigue has accumulated.
- 5For hypertrophy, prioritise volume, effort and progression over the periodisation model.
Conclusion
Periodisation is planned variation, and for strength it pays off — particularly the undulating approach in trained lifters. For muscle growth it is a scheduling tool rather than a stimulus.
You do not need an elaborate system. A heavy day, a moderate day and a sensible block structure capture most of the benefit.
References
- [1]Williams TD, Tolusso DV, Fedewa MV, Esco MR. Comparison of Periodized and Non-Periodized Resistance Training on Maximal Strength: A Meta-Analysis. Sports Medicine. 2017;47(10):2083–2100. Meta-analysis doi.org/10.1007/s40279-017-0734-y
- [2]Moesgaard L, Beck MM, Christiansen L, Aagaard P, Lundbye-Jensen J. Effects of Periodization on Strength and Muscle Hypertrophy in Volume-Equated Resistance Training Programs: A Systematic Review and Meta-analysis. Sports Medicine. 2022;52(7):1647–1666. Systematic review and meta-analysis doi.org/10.1007/s40279-021-01636-1
- [3]Bell L, Strafford BW, Coleman M, Androulakis Korakakis P, Nolan D. Integrating Deloading into Strength and Physique Sports Training Programmes: An International Delphi Consensus Approach. Sports Medicine – Open. 2023;9(1):87. Expert consensus (Delphi study) doi.org/10.1186/s40798-023-00633-0
This guide summarises published research for healthy adults. It is general information, not medical advice — if you have a health condition, injury or take medication, talk to a qualified professional before changing your training, diet or supplements.
