Traditional vs. Undulating Periodization in the Context of Muscular Strength and Hypertrophy: A Meta-Analysis

There is currently no consensus regarding the best periodization model to increase muscle strength and hypertrophy. However, most recently the undulating periodization (UP) has been believed to be better than traditional periodization (TP) model. The purpose of this study was to conduct a meta-analysis to investigate whether the UP is superior to TP to induce gains in strength and hypertrophy. Studies were searched in databases covering three idioms. Twenty-five studies met the inclusion criteria, allowing 72 and 6 effects sizes (ES) to strength performance and hypertrophy, respectively, covering 400 males and 192 females. Duration of training protocols ranged 6 to 16 weeks. Continuous data from maximum strength (1RM), isometric, power, and muscular endurance (RMs) tests were collected. Additionally, only gold-standard measures were included for hypertrophy assessment. Statistical analyses were performed using dedicated software for meta-analysis. Considering the pooled data, UP was significantly (P = 0.005) larger than TP model to 1RM test (ES= 0.22; 95% IC= 0.07, 0.38). However, there was no significant difference (P > 0.05) between UP vs. TP for power (ES= -0.04; 95% IC= -0.29, 0.22), RMs (ES = 0.20; 95% IC = -0.07, 0.48), isometric strength (ES = -0.13; 95% IC = -0.50, 0.24), and hypertrophy (ES = 0.32; 95% IC = -0.07, 0.71). UP model seems better than TP model to improve maximum strength performance, but not to power, muscular endurance, isometric strength, and muscle hypertrophy.