Periodization is systematically changing the weight used and reps completed per set. The two main forms of periodization are: linear and undulating. Linear is the more traditional form, and it involves gradually increasing the weight used with a concomitant decrease in reps per set in a linear fashion over time. Undulating involves a more sporadic change in weight and reps with weight jumping up and down and back up in an undulating fashion over time. There is some debate over which form of periodization works best for increasing strength gains. 


Researchers from the University of Alberta trained male lifters in a 12-week periodized strength-training program consisting of either a traditional linear periodized scheme that progressively increased the amount of weight they used each week or an undulating periodized scheme that changed weight each week, but not linearly. 


The researchers reported in a 2011 issue of the Journal of Strength and Conditioning Research that the guys following the linear periodized program increased their 10-rep max strength on all exercises significantly more than the guys following the undulating program. For example, the guys training linearly increased their 10-rep max on the squat by more than 50%, while the guys following the undulating plan only increased their squat by 30%. 


The improvements may have occurred because the undulating group experienced more delayed-onset muscle soreness and fatigue, which could have compromised their training and thus their strength gains. 


When you are focusing on building more muscle strength, use a linear periodized program that progressively increases the weight you use on each exercise every week. For example, start with very light weight in Week 1, such as a weight that allows you to complete 15–20 reps; by the final week you’ll be lifting weight heavy enough to limit you to 2–3 reps per set.


REFERENCE J.M. Apel, J. Strength Cond. Res., 25(3): 694-703, 2011703, 2011