Load undulation is a way of dosing training loads within your programming, and it assumes that training volume and intensity should vary systematically, not just week to week, but within the same week or even within the same day.
It’s not a new concept. It’s backed by decades of sports science research and it’s the foundation of programming for practically all athletes, especially high-level ones. Yet in many cases, this load-modeling system is never actually implemented.
Why? Because applying it well without the right tools is complicated. Manually calculating volume and intensity changes for every athlete, in every session, for weeks on end, is extremely time-consuming work.
The problem is that if we don’t undulate training loads, training stops being optimal.
In this article, we explain why, how load undulation works, and how to implement it without it consuming hours of your work.
Linear periodization, progressively increasing load week after week, works at first, with beginner athletes who respond to almost any stimulus. But it has a clear limit: the body adapts to the predictable loading pattern and stops responding.
The most frequent problems of linear progression without undulation:
Load undulation is based on three well-documented physiological principles:
Different combinations of volume and intensity produce different adaptations. High loads with few reps tend to focus on max strength development. Moderate loads with medium reps develop hypertrophy or power depending on execution velocity. Low loads with many reps develop muscular endurance and metabolic recovery.
Adaptation happens during recovery, not during training. After a high-intensity stimulus, the body needs 48-72 hours to supercompensate. If the next stimulus arrives before that supercompensation happens, fatigue accumulates. If it arrives too late, the adaptation window is lost.
Undulation allows alternating stimuli with different recovery demands, so the athlete can train at high frequency without accumulating chronic fatigue.
Research in training neurophysiology shows that the central nervous system habituates to repetitive loading patterns. When the stimulus is always the same, the adaptive response decreases. Systematic variation, in volume, intensity, and exercise type, keeps the nervous system “alert” and maximizes adaptations.
Volume and intensity vary week to week within the mesocycle. For example:
It’s the simplest model to implement and the most suitable for athletes who train each muscle group 2-3 times per week.
Volume and intensity vary session to session within the same week. For example, in a three-session week:
This model is backed by multiple meta-analyses showing superiority over linear periodization for the simultaneous development of strength and hypertrophy. It’s more complex to design but produces better results in intermediate and advanced athletes.
Within a single session, different qualities are trained in separate blocks. For example: a max strength block (heavy 3x3) followed by a power block (4x5 at max velocity) followed by a metabolic block (moderate 2x15).
It’s the most cognitively demanding model for the coach, but the most time-efficient for athletes with limited schedule availability.
Volume is expressed in weekly sets per muscle group. Current scientific literature suggests a range of 10-20 weekly sets per muscle group to maximize hypertrophy, with adjustments based on the athlete’s level and the phase of the macrocycle.
In an undulating model, weekly volume varies from one week to the next, within a range that allows supercompensation without accumulating chronic fatigue.
Intensity is expressed as a percentage of 1RM or as RPE (rating of perceived exertion). In an undulating model:
Density (work/rest ratio) and weekly training frequency must be adjusted in parallel with volume and intensity. High-intensity weeks require longer rest between sets and lower weekly frequency.
Here’s the elephant in the room: everything you just read is correct, science-backed, and improves athletes’ results. And it’s also extremely tedious to calculate and manage manually for multiple athletes.
For a coach with 20 clients, implementing DUP correctly in Excel means:
In practice, most coaches abandon proper undulation not because they don’t want to apply it, but because the time cost is prohibitive.
Nexo Kinetics solves exactly this problem. The planning module lets you configure load undulation directly in the plan, the system automatically calculates the percentages and volumes for each session, adjusts them when the athlete’s assessment data changes, and generates deload weeks at the right moments of the macrocycle.
What used to take hours of Excel work now takes minutes. And most importantly: it can be replicated for every athlete without additional effort proportional to the number of clients.
The only way to know if an undulation model is producing the expected adaptations is to measure. The key indicators:
In Nexo Kinetics, all this data is captured automatically and can be compared between blocks with graphical visualization. Load undulation and the monitoring of its effects are part of the same integrated workflow.
Load undulation is probably the programming principle with the strongest scientific backing and the lowest real adoption rate in the personal training market. The gap between what science says and what most coaches do is enormous.
That gap exists because correct implementation is complex without the right tools. With the right tools, it’s the most powerful differentiator you can incorporate into your methodology.
Nexo Jump measures vertical jump, contact time and RSI with millimetre precision — and the software turns that data into programs for your athletes.