Swimming: how intensity is distributed and what studies say about methods
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Intensity distribution: what elite swimmers do
A 2021 systematic review examined 9 studies of highly trained swimmers. It found that sprinters typically follow a polarized or threshold distribution, middle-distance swimmers (200-400 m) threshold or pyramidal, and distance swimmers mostly pyramidal. The authors note most studies are observational: they show what is done, not what works best, and training is usually organised in wave-like cycles.1
"Polarized" means a lot of easy work, a little very hard work and little in between; "threshold" puts more near threshold; "pyramidal" has more easy, less moderate and even less hard. These are descriptive labels: their boundaries depend on how threshold is measured.
Polarized versus threshold: one study, 6 weeks
In a crossover study of 22 elite swimmers, six weeks of polarized training (81% at low intensity) gave a small to moderate improvement in 100 m performance compared with six weeks of threshold training, with less perceived fatigue. No clear differences appeared in physiological measures.2 These are young swimmers, one race-distance test (100 m) and a short period: it does not extend to someone preparing a triathlon.
HIIT and low-volume training
A 2026 meta-analysis of 11 studies (237 competitive swimmers, mean age about 15) reports that HIIT improves VO₂max and performance, with larger effects in programmes of at least 8 weeks. For long distances (800 m and above) the guidance is described as "preliminary". We read the abstract only.3 An earlier review of low-volume, high-intensity training finds promising results but concludes that longer studies are needed: in 4 of 7 studies swimming performance improved significantly and in none did it get worse. We read the abstract only.4
Dryland strength
A 2022 systematic review of dryland and in-water resistance training reports mean performance gains of around 2-3%, similar across the types of work, and concludes there is no clearly better method. The full text separates in-water resistance, stroke-like dry-land work and general strength. It excludes masters, triathlon and open water, so findings should not be transferred automatically to these settings.5 For strength aimed at endurance athletes see Strength for endurance.
For protocols, rests and specific examples see Strength for swimming.
Tapering before a race
A meta-analysis of competitive athletes across several sports (not swimming alone) concludes that a taper of about 2 weeks, with volume reduced exponentially by 41-60% and no change in intensity or frequency, is the most effective strategy among those analysed.6 Treat it as a general reference: it was not verified in amateurs or in swimming alone.
Structure example: short or long intervals
An 8-week study of 24 former swimmers compared two interval programmes with the same total distance and the same intensity: 12-16 × 50 m with 15 s rest versus 6-8 × 100 m with 30 s. Both groups improved in the 100 and 400 m tests and in maximal aerobic speed versus the control group, with no significant difference between the two programmes.7
As a teaching example it shows that the set structure (50 or 100 m) mattered less than total volume and intensity, in that group and those 8 weeks. It is not a recommended session: the abstract gives no intensity level in applicable terms and the group is not current amateurs.
What we know and what we do not
- We know: how competitive swimmers train by race distance, and that some HIIT and polarized programmes gave small improvements in young and elite groups.
- We do not know: which distribution is best for an amateur, a triathlete or someone who swims 2-3 times a week. Direct studies are missing.
- We do not publish swim zones, set paces or intensity percentages as if they were your data. A zone needs a test; see critical swim speed (CSS) and its limits.
How we reviewed it
Document review: 3 systematic reviews or meta-analyses and two experimental studies, mostly read as abstracts only.
Limits. Competitive, often young swimmers; observational or short studies; full text not read for most. Does not apply to amateurs and triathletes.
Sources
- González-Ravé, Hermosilla, González-Mohíno, Casado, Pyne. Training Intensity Distribution, Training Volume, and Periodization Models in Elite Swimmers: A Systematic Review. International Journal of Sports Physiology and Performance, 2021. DOI (abstract read)
- Pla, Le Meur, Aubry, Toussaint, Hellard. Effects of a 6-Week Period of Polarized or Threshold Training on Performance and Fatigue in Elite Swimmers. International Journal of Sports Physiology and Performance, 2019. DOI (abstract and part of the introduction read)
- Jin, Chen, Finlay, Cuenca-Fernández, Zhong, Gao, Wu. The effects of high-intensity interval training on competitive swimmers: A systematic review and meta-analysis. Journal of Science and Medicine in Sport, 2026. Abstract (abstract only)
- Nugent, Comyns, Burrows, Warrington. Effects of Low-Volume, High-Intensity Training on Performance in Competitive Swimmers: A Systematic Review. Journal of Strength and Conditioning Research, 2017. PubMed (abstract only)
- Fone, van den Tillaar. Effect of Different Types of Strength Training on Swimming Performance in Competitive Swimmers: A Systematic Review. Sports Medicine - Open, 2022. Springer · PubMed (full text)
- Bosquet, Montpetit, Arvisais, Mujika. Effects of tapering on performance: a meta-analysis. Medicine & Science in Sports & Exercise, 2007. PubMed (abstract read)
- Dalamitros, Zafeiridis, Toubekis, Tsalis, Pelarigo, Manou, Kellis. Effects of Short-Interval and Long-Interval Swimming Protocols on Performance, Aerobic Adaptations, and Technical Parameters: A Training Study. Journal of Strength and Conditioning Research, 2016. PubMed (abstract)
Sources rechecked on 28 October 2026. Where we write "abstract only" we did not read the full text: results are as stated by the authors.