Undulating Periodization: Changing the Load and Reps From Session to Session
Quick Intro
Undulating periodization is a way of planning resistance training in which the weight and the number of repetitions go up and down repeatedly, instead of moving steadily in one direction over many weeks. The most common form is daily undulating periodization (DUP), where each session in the same week has a different goal: one heavy, one moderate and one light. A weekly version also exists, where the change happens from one week to the next.
The Idea in Plain Terms
Periodization means planning training in phases over time. The older and better known approach, linear periodization, starts with lighter weights and higher repetitions and moves gradually toward heavier weights and fewer repetitions across a block of several weeks. Intensity (how heavy the load is compared with the most you could lift once, often written as a percentage of your one-repetition maximum or 1RM) rises while volume (the total sets and repetitions) falls.
Undulating periodization keeps all of those ranges in play at once. The same lift, say the squat, appears several times a week, and each session asks for something different:
- A heavy day uses a load near the top of what you can manage, for low repetitions, typically 3 to 5.
- A moderate day uses a medium load for 8 to 10 repetitions.
- A light day uses a lighter load for 12 to 15 repetitions, often with a quicker, smoother pace.
The reasons usually given are practical. Training each rep range several times a week gives more frequent practice with the lift. Changing the demand from day to day may also keep sessions from feeling repetitive, and a lighter day gives joints and tissues a break between heavy ones. Whether the variety itself drives extra progress is the question the research tries to answer, and it is covered below.
A Worked Example
This is an illustration of the pattern, not a prescription. A lifter squats three times a week with a 1RM of 100 kilograms.
| Day | Goal | Load (approximate) | Sets and reps | Effort |
|---|---|---|---|---|
| Monday | Heavy | 85 kg (about 85% of 1RM) | 4 sets of 4 | The last rep of each set is hard but clean |
| Wednesday | Moderate | 72 kg (about 72%) | 3 sets of 9 | The last two reps take real effort |
| Friday | Light | 62 kg (about 62%) | 3 sets of 14 | Brisk reps, a couple left in reserve |
The following week the same pattern repeats, with the loads nudged upward when the target repetitions feel manageable. Bench press, deadlift or rows can follow the same layout, and lifts do not all need the same pattern on the same day.
What the Research Shows
Muscle size. A 2017 systematic review and meta-analysis by Grgic and colleagues pooled 13 studies comparing linear and daily undulating programs. The difference in muscle growth was effectively zero, and the authors concluded the two are likely to have similar effects on hypertrophy (muscle growth). They noted that trained lifters and clinical groups were underrepresented.
Strength. The picture is less settled. An earlier review covering 17 studies found no significant difference between linear and undulating models for upper or lower body strength. A later analysis by Stronger by Science, which pooled a similar set of studies, found a small edge for undulating programs overall and a clearer one among trained lifters, with no meaningful difference among beginners. A 2022 review of programs matched for total volume pointed the same way: higher one-repetition maximum gains for undulating training in resistance-trained people only.
Limits of the evidence. Most studies lasted between 6 and 16 weeks, so little is known about what happens over years. Few participants were highly trained, and even the groups labelled trained often progressed at rates typical of less experienced lifters. Real programs also mix linear, undulating and block elements, which these studies mostly did not test. A fair reading is that undulation may help experienced lifters somewhat with strength and is unlikely to matter for muscle size when weekly volume is matched.
Who It Suits
- Lifters who train the same lift two or three times a week and want a structure for varying it.
- Trained lifters whose steady linear progress has slowed.
- People who find the same set and rep scheme every session dull and are more likely to keep training when sessions differ.
It adds little for a complete beginner. Early in training almost any sensible program produces fast progress, so the choice of model matters far less than showing up and adding load gradually. Someone who trains a lift only once a week has no room to rotate heavy, moderate and light days, and a weekly version may fit better.
How to Use It
- Pick the lifts and the number of days. Two to four sessions per lift per week is typical for the daily version.
- Assign each day a clear role and keep the roles distinct. A heavy day is heavy and a light day is light, with the moderate day sitting between them.
- Keep total weekly volume sensible and roughly steady. Moving between rep ranges does not replace the need for enough hard sets across the week.
- Add load gradually when you reach the top of the repetition target on a given day, and track each day’s numbers separately.
- Leave at least a day between heavy sessions for the same lift, and plan an easier week now and then. This is often called a deload.
Common slips are making every day moderate by habit, running heavy days with no warm-up sets, and changing exercises as well as rep ranges every session, which makes progress hard to read.
Common Misunderstandings
It is not random. The sessions rotate in a planned order, and the plan still builds toward heavier loads over time.
It is not “muscle confusion”. That popular phrase suggests muscles are tricked into growing, and the research above does not support it. The variation is a way to practice different loading ranges, nothing more mysterious.
It does not replace linear progression. Many strong programs add a slow upward drift in load on top of the weekly rotation.
FAQ
Is undulating periodization better than linear periodization? For muscle growth the studies show no difference when volume is equal. For strength it may be slightly better in trained lifters, and the evidence is limited by short study length.
How is daily undulating different from weekly undulating? In the daily version the rep range changes between sessions within a week. In the weekly version the whole week follows one range and the next week switches. The daily version has more supporting research.
Can a beginner use it? Yes, though it is not necessary. A simple program that adds weight gradually works well at the start, and undulation can be introduced later.
How long should one block last? There is no studied optimum. Programs commonly run 4 to 12 weeks before a change of lifts, a reset of loads or a lighter week.
Does it work for exercises other than barbell lifts? The principle applies to any loaded exercise where reps and load can be changed. Bodyweight movements can vary the difficulty of the variation or the pace instead of the load.
Where This Comes From
Grgic J and colleagues, 2017, systematic review and meta-analysis of linear and daily undulating periodized programs and muscle hypertrophy (PeerJ). Harries SK and colleagues, 2015, review of linear and undulating periodized programs and muscular strength. Stronger by Science, analysis of periodization data. Systematic review and meta-analysis of periodization in volume-equated resistance training, 2022.
Related to: Barbell Back Squat, Barbell Bench Press and Barbell Deadlift, the lifts most often arranged in an undulating week. Closely related ideas: linear periodization, block periodization, deload weeks and progressive overload.