31.10.2026 · 5 min read
Three words keep coming up in arguments about endurance training: pyramidal, polarised, threshold. In the three-zone model, zone 1 lies below LT1, zone 2 between LT1 and LT2, and zone 3 above LT2. A pyramidal distribution means Z1 > Z2 > Z3: a lot of easy work, less moderate, even less high-intensity. A polarised one combines a lot of easy work, little moderate work and a noticeable share of high-intensity work. A threshold one puts more emphasis on the middle zone.
TID describes where the work was distributed. Periodisation answers a broader question: how volume, intensity, specificity, recovery and preparation for competitions changed over time. The two concepts are often confused, and in one article they usually appear together.
The work by Gao and colleagues is a "collective case study": a detailed description of the preparation of five elite female swimmers over 200–1500 m (four at international level and one national; mean age about 20 years) across a 52-week macrocycle. The season had two national championships (in weeks 29 and 52), three altitude camps at 1,890 and 2,400 m and two tapers before competitions.
The intensity distribution changed from block to block. The base block was mostly pyramidal: roughly 48–54% of volume in zone 1, 30–36% in zone 2 and 15–16% in zone 3. The altitude blocks were polarised — about 72–75% in zone 1, only 5–8% in zone 2 and 18–20% in zone 3. Before specific work, in the sharpening blocks, the share of the middle zone rose to 41–43%, that is, the model became threshold.
The authors compared changes in results with the smallest worthwhile change (about 0.24%). At the first championship 12 of 20 "athlete × event" changes (60%) exceeded this threshold, and 10 of them were improvements; at the second, 18 of 20 (90%), of which 13 were improvements. An important detail: exceeding the threshold includes worsening, so "60%" and "90%" cannot be read as the share who improved.
This is a valuable, detailed case of real elite practice. But n=5, the absence of a control and simultaneous altitude camps do not allow the cause of the changes to be established. Some important factors were not measured, including dry-land load, iron and menstrual cycle phases; blood was drawn only four times in the year, and internal load (for example, perceived exertion of sessions) was not recorded. The authors themselves describe the results as associations and exploratory data, not proof of causation.
The study supports a flexible idea: the model is chosen for the aim of the block, the event, the athlete's level and the calendar. It does not prove a mandatory sequence of "pyramid → polarised → threshold" and does not transfer directly to an amateur runner: elite swimmers have different volume, different load and different support.
For planning, it is more useful to define target races, available volume and tolerance, and then track the individual response. The name of a model does not replace load management.
When people say "72% in zone 1, 7% in zone 2 and 20% in zone 3", they mean the share of training volume done in each intensity zone, not the number of sessions or the rest time. The zones are tied to lactate thresholds — and, as the review on running thresholds shows, the thresholds themselves can be determined by different methods. If the zone boundaries are drawn differently, the same distribution can look like a different model. One more caveat: zones at altitude were determined using thresholds measured at sea level, so their assignment is approximate.
The work does not compare the pyramidal, polarised and threshold models with each other and does not say which gives a greater gain. There is no control group that went through the same season on a different scheme. There are no data on how results would have changed without altitude camps or with a different volume. The study is therefore useful as an illustration of how professional coaches combine distributions over a year, not as a recipe.
For an amateur, the main practical takeaway is not to copy someone else's season wholesale, but to understand the logic: a large volume of easy work as a base, limited but high-quality high-intensity sessions, and raising the share of the "middle" zone deliberately, before specific races. And always track how you feel, sleep and recover, so that the plan can be adjusted in time.
A detailed description of a real season is a strength. The weaknesses are obvious: five athletes, no control group, no randomisation, several interventions acting at once, altitude zones set from sea-level thresholds, and competition conditions not documented. It is a map, not a trial.
No universal winner has been found. The work shows how three distributions can coexist within a season, but remains a descriptive map of one team rather than a test of the effectiveness of the schemes.
Tags: periodization, training intensity distribution, swimming, endurance, case study
Research on training, nutrition and recovery: the key points worth knowing. One email a week with the new Sport in Luxembourg articles: title, short description and a link to read.
We use cookies for visitor analytics. You can accept or decline their use. Learn more in our Privacy Policy
