Periodization refers to the manipulation of training variables over time or the long-term planning of training, with the goal of preventing overtraining while optimizing peak performance.[1]
Linear periodization (LP) is characterized by increasing intensity and decreasing volume (i.e., lifting heavier loads for fewer reps) over time. Undulating periodization (UP) is characterized by more frequent variations in volume and intensity than LP. Weekly UP (WUP) involves fluctuations in volume and intensity from week to week, whereas daily UP (DUP) involves fluctuations in volume and intensity from workout to workout.
For example, consider a training program that involves performing resistance exercise twice per week for 8 weeks. Sample LP, WUP, DUP, and nonperiodized programs might look like this:
| Program type | Sample exercises |
|---|---|
| LP | 4 sets of squats using 70% of 1-repetition maximum (1RM) each workout for 4 weeks, followed by performing 3 sets of squats using 80% of 1RM each workout for 4 weeks |
| WUP | 4 sets of squats using 70% of 1RM each workout in week 1, followed by performing 3 sets of squats using 80% of 1RM each workout in week 2; alternate between weeks 1 and 2 for the rest of the 8 weeks |
| DUP | 4 sets of squats using 70% of 1RM in the first workout of the week and 3 sets of squats using 80% of 1RM in the second workout of the same week, for all 8 weeks |
| Nonperiodized | 3 sets of squats using 75% of 1RM every single workout for 8 weeks |
A 2022 meta-analysis reported that periodized programs were superior to nonperiodized programs for increasing 1RM strength, with a trivial-to-small effect size reported.[2] Concerning the type of periodization, UP (which included studies that utilized either DUP or WUP) was superior to LP for increasing 1RM strength, with a trivial-to-small effect size reported. Additionally, UP was only superior to LP in studies featuring trained participants.
In contrast, periodized programs were not reported to be superior to nonperiodized programs for muscle gain.[2] It may be the case that the methods used to assess changes in muscle size were not sensitive enough to detect small differences between groups, as a number of the included studies used indirect measures. However, there is good reason, physiologically, to doubt the superiority of periodized programs for muscle gain.
Because a variety of loads produce similar muscle gain,[3] and high and low loads do not appear to reliably induce different degrees of type I and type II fiber hypertrophy,[4] there doesn’t seem to be any strong physiological rationale to substantiate how varying training loads across a training program would produce superior muscle growth,[4] at least under ideal conditions. It may be the case that varying training loads increases the individual’s motivation to exercise, fostering greater adherence to the program and increasing the amount of effort they exert during their workouts, which would theoretically enhance muscle gain over the long term.