In exercise science, the term periodization refers to the method by which you change, progress, or vary your training program over time. While the term is used in both strength and endurance training, it is seen most commonly in reference to strength training, and that's what we're focused on here.

Periodization can be as simple as increasing the weights over time, or as complex as varying the volume and intensity of your workouts throughout the week, varying that setup every few weeks, and completely changing the entire training plan every few months. First, let's examine the periodization training options available. 

5 Common Types of Periodization Training

1. No Periodization At All

The first option is simple, and it’s what most recreational trainees do: Don’t periodize. Note that this doesn’t mean you don’t make progress, only that the fundamentals of your program — your volume, frequency, and intensity — don’t change over time.

In a non-periodized training program, each exercise will have a target rep range and number of sets. When you find yourself able to exceed those, you raise the weight. (That’s how you make progress.)

Related: The Interference Effect: Do Cardio and Resistance Training Conflict?

This is a perfectly effective method for strength training, and all you need when you’re first starting out. It also works for in-season athletes, who need to keep their strength training light and simple to focus on staying fresh for competitions.

In general, studies find that non-periodized training works just as well as periodized training for untrained individuals.  

2. Linear Periodization

In linear periodization, training intensity — the heaviness of the weight — is increased over the course of a training cycle, with a corresponding decrease in reps performed (and sometimes the number of sets as well). Many people train this way, as it’s simple and makes it easier to lift heavier over time, which feels like progress.

The thing is, linear periodization is no better than non-periodized training for building muscle.

Now, linear periodization does seem to work better for building strength, but there’s a big confounder here. Because strength is tested by lifting heavy weights for one rep, and linear programs have you lift heavier for fewer reps over time, you’re “training to the test” later in the program, more so than earlier on. If pure strength was your goal, you’d probably do even better by just lifting heavy right from the start.  

3. Volume-Based Periodization

In volume-based periodization, you increase the number of sets performed over time, effectively doing more work as the training cycle goes on.  

Training volume is the most important determinant of muscular hypertrophy. This just means that more training volume equals more muscle. More advanced trainees can handle more training volume, so it makes sense that you’d want to do more volume over time.  

Related: These Are the 5 Most Important Exercises for Explosive Power

However, the time scales don’t match up. Your optimal training volume goes up over the course of years, not weeks. It shouldn’t increase significantly during a single training cycle, and if you can handle more training volume now, you should be doing more now, not later.   

4. Daily Undulating Periodization

In a daily undulating periodization (DUP) training scheme, workouts alternate between high-weight, low-rep and low-weight, high-rep, while otherwise keeping the same exercises and usually the same number of sets. For instance, you might squat for three sets of five reps on Mondays, and three sets of 10 reps at a lower weight on Thursdays.    

In one study of 200 experienced lifters who were divided into four groups of 50 each, DUP outperformed linear, reverse linear, and no periodization.

While several studies have confirmed that DUP is superior for building strength, only one has found that daily undulating periodization is better for building mass.  Most studies and meta-analyses find no difference for muscular hypertrophy relative to linear or no periodization.  

That said, short study durations may be an issue here. Over the long run, strength and mass tend to be more highly correlated, as you can only gain so much strength without also building mass.  

5. Density-Based Periodization

A more recent fad is toward density-based periodization, wherein training density is progressively increased by progressively reducing rest periods. The idea here is to produce more lactic acid buildup and more fatigue. (You’ll often hear this presented side by side with “lactic acid training.”)  

In an eight-week study involving 20 young men, density training failed to produce better results than maintaining constant rest periods. Furthermore, the density training group gradually suffered from reduced training volume, although this did not lead to significantly worse strength or mass levels. This finding was later replicated in a study where both groups also supplemented with creatine.  

Related: The 100+ Best Exercises for Your Entire Body

Given that training volume does appear to be the primary driver of muscle growth, over a longer period of time and/or with a larger sample size, you would expect to see the density training group actually do worse, as density training reduces training volume.

Which Periodization Training Scheme Is the Best?

For most people, daily undulating periodization is going to be the best way to go.  It produces the greatest strength gains, and — over the long run — possibly better mass gains as well.

For total newbies, no periodization is necessary — just keep it simple. For athletes training in-season, periodization may also be unhelpful, as it’s best to keep things light and simple and focus on staying recovered for competitions and races.