What Is Periodisation? Base, Build, Peak and Taper Explained

Short answer: periodisation means organising your training into phases, each with one main job, so you arrive at your most important race fit and fresh rather than simply tired. The usual version has four phases: base (build the aerobic engine), build (add race-specific harder work), peak (sharpen) and taper (cut the load so fitness can show).

In practice: pick your one big goal race of the year (your "A race"), count back from its date, and protect a taper of about two weeks before it (often one week for short races). This four-phase plan is one practical template for a single big race rather than the only way to periodise, and how long each phase lasts depends on your starting fitness.

Why bother organising training into phases?

You can't train hard, long and race-specific all year: fatigue piles up and you may peak at the wrong moment. Phases manage that: general fitness first, race-specific fitness on top, then rest so it shows on the day.

Issurin's review calls this the "traditional" model and notes it has stayed much the same since it was first proposed (1). The general-then-specific order is long-standing coaching practice rather than a tested finding.

What should you do? Plan backwards from one A race

Where should you put your effort? As a coaching rule of thumb, beginners and people coming back from a break gain most from the base phase: weeks of consistent, mostly easy training beat any clever structure. If you've already finished a few races and train regularly, the extra gains usually come from a race-specific build phase and a proper taper.

Four effort words used in this article, for readers who don't know their numbers:

• Easy: you could chat in full sentences.
• Threshold: comfortably hard; roughly what you could hold for about an hour in a race. Breathing is deep and steady and you can speak only in short phrases. It's a practical approximation, not one exact physiological point.
• Race pace: the effort you plan to hold in your A race.
• Hard intervals: you could only manage a word or two.

For most amateurs with one big race a year, as a rough guide for a season of about 20–24 weeks:

Phase	Typical length	Main job	How it should feel
Base	8–12 weeks	Aerobic endurance, technique, consistency	Mostly easy and conversational
Build	6–8 weeks	Race-specific intensity and longer key sessions	Two hard days a week, the rest easy
Peak	2–3 weeks	Race-pace rehearsals, sharpening	Hard sessions short and sharp, fewer of them
Taper	About 2 weeks	Shed fatigue, keep fitness	Fresher by race day; the first days can feel flat

These lengths are coaching conventions: if you train all year you may need less base, and after a long break, more.

If you have fewer weeks, protect the taper first. Then trim the phase that matters least to you:

• You train regularly all year: shorten the base.
• You're newer or returning from a break: keep the base and shorten the build.

How it works, in plain words

Training is a stress your body adapts to when it is the right kind, repeated, and followed by enough recovery. Early on you build the broad base everything else rests on: a bigger aerobic engine and the durability to train more. Later you add the specific, harder work that turns that engine into race speed. Hard work produces fatigue as well as fitness, so this model concentrates it later, in controlled doses. Base doesn't mean no intensity: many coaches keep a little all year; what changes is how much, and how race-specific. At the end you drop the volume so the fatigue clears faster than the fitness fades.

Phases describe how training changes across the season. How each week splits between easy and hard work is a separate question (the science section covers it). The two are linked, since the split often shifts across phases, but neither decides the other.

What does each phase look like in a real week?

These examples are for someone already coping well with about eight hours a week; they're illustrations, not a starting plan. Scale them to your hours, and if you're newer, start with one key session a week, not two.

Base week. Almost everything easy, plus one session of steady or threshold work, such as 3 × 8 minutes comfortably hard with 3 minutes easy between, and one long easy session. Technique work (swim drills, cadence, short relaxed sprints called strides) fits here.

Build week. Two hard sessions in total each week, whatever your sport (for a triathlete, for example, one on the bike and one on the run), with everything else easy.

• Olympic-distance triathlete: on the bike, 4–5 × 6–8 minutes at threshold effort with 3 minutes easy between; on the run, 3 × 10 minutes at 10 km race effort (hard; at or a little above threshold) with 2–3 minutes of jogging.
• Experienced marathoner: a long run with two or three 15–25-minute blocks at marathon pace (steady; you could speak in short sentences), plus a midweek run of 3–4 × 8–10 minutes at threshold effort. That's demanding; if the long run is near your limit, drop the threshold run.

The long session grows gradually, while you're recovering well. There's no single right rate: ten extra minutes means more to a 45-minute runner than a two-hour one, and your volume, history and injuries matter. Lengthen it when the current length feels manageable, not because another week has passed. As a rough guide, one common step is about 10–15 minutes on a long run or 15–30 minutes on a long ride at a time, held or shortened in easier weeks. If you're still sore or tired two days later, go back to the previous length.

Peak weeks. Key sessions become dress rehearsals: race pace, kit and fuelling. For short races they get shorter and sharper. For a marathon or long-course triathlon, as a rule of thumb, the longest race-specific sessions fall around three to five weeks out (a long run with marathon-pace blocks, or a long ride or bike-then-run "brick" at race effort), before the taper. In many plans, total hours drop a little.

Many plans add an easier week every three or four weeks: roughly a third less volume, one short quality session kept. That's a rule of thumb; adjust it to how you recover.

What if a session goes badly?

One bad session means little: go easy and try again after a good night's sleep. If two key sessions in a row go badly, swap the next hard day for an easy one and look for the cause: accumulated fatigue, an illness coming on, not eating enough for the training, poor sleep or life stress, or targets set too high. Keep things short and easy, or rest, until you feel normal, and deal with the cause before you push on.

If you still feel flat after a week of easy training, or you have chest pain, dizziness or an illness that won't clear, see a doctor before you return to hard sessions.

How should you taper?

How long

A meta-analysis of 27 studies in competitive athletes found the most effective taper lasted about two weeks, with training volume cut by 41–60% and intensity and frequency unchanged (2). For a race you care about, start about two weeks out; as a coaching rule of thumb, if your training load is modest, a shorter taper may be enough.

Before a short race such as a sprint triathlon or 10 km, many coaches use a week. Shorter tapers can work: a later meta-analysis of 14 endurance studies found tapers of up to 7, 8–14 and 15–21 days all improved time-trial performance, with the largest effect at 8–14 days, though it didn't compare race distances (3). How tired you are matters as well as the distance.

How much to cut

Here is a simple way to do it. It is a coaching illustration, not a tested protocol. Start from a normal build week (your usual hours before the peak and taper):

• First taper week: about 30–40% less. From a normal 8 hours, about 5–5½ hours.
• Race week: about 50–60% less. From 8 hours, about 3–4 hours of training, not counting the race.

Make each week lighter towards its end. In the meta-analysis, volume came down progressively (the authors say exponentially: bigger cuts early, then levelling off), not in one step, and the 41–60% compares the taper with the training before it (2). Across both weeks, the example above comes to roughly 40–50% less, at the lower end of that range. The research supports a range of tapers, not one recipe: Mujika and Padilla's review reports cuts of up to 60–90% and tapers from 4 to more than 28 days (4).

Keep a few short, fast efforts

Do fewer hard intervals, but keep the speed: the reviews found performance held up best when intensity was kept (2–4). That means keeping some short efforts at race intensity, not the same amount of hard work. A typical coaching example is 4–6 × 1–2 minutes at race effort with easy recovery between. Before a marathon or long-course race, use a few short blocks at race pace instead, finishing fresh.

Keep most of your sessions

Make sessions shorter rather than dropping them: Mujika and Padilla's review, drawn from trained, competitive athletes, suggests cutting frequency by no more than about 20% (4). Expect to feel odd. Many athletes report sluggish or restless legs early in a taper; in coaches' experience this usually passes by race day.

What happens to your fitness numbers

Many training apps show three estimates, under names that vary by app: fitness (CTL), fatigue (ATL) and form (TSB). Tito shows them too. They come from a calculation on your training load, not from measuring your body. Fitness is a slow-moving average of your daily training load in which recent days count most (the standard setting is a 42-day time constant), fatigue a fast-moving one (7 days), and form is fitness minus fatigue.

During a two-week taper at roughly half your usual load, those settings make the fitness number dip by around 10–15% and the fatigue number fall by 40–50%, so form rises. That dip is normal: it's mostly the calculation rather than lost fitness, because a good taper sheds fatigue while keeping adaptations (4). Don't add training to chase it. There's no single race-day form value that suits everyone, so treat the trend as one indicator alongside how you feel.

Other options: block periodisation and more than one A race

Block periodisation

The traditional model develops several abilities at once. Block periodisation concentrates on a few selected abilities at a time, in successive blocks, and comes in more than one version; Issurin describes general development, then more specific work, then sharpening (1).

Is it better? Possibly, by a little. A review found small benefits in the lab measures it could pool, such as VO2max (the most oxygen your body can use per minute), and larger effects on performance in studies it could only describe; the studies were small and generally low in quality (5). In one cycling study, riders repeated a cycle of one week packed with five interval sessions followed by three weeks with one each, with similar total training (6). A later study that matched the training load found no difference in time-trial performance (7). Treat it as a reasonable option for experienced athletes who like variety, not an upgrade everyone needs. As a conservative coaching view, a concentrated hard week is a big jump in load, so don't start there if you're new or injury-prone.

More than one important race

With two A races, plan two shorter cycles, each with its own build, peak and taper, leaving time to recover, rebuild and taper again. Coaches often suggest at least eight to ten weeks between them, but that's a rule of thumb: after a marathon or long-course triathlon you may need considerably longer.

B and C races are smaller events you use as training. Treat them as hard training sessions with only a few easy days before them, and recover afterwards in proportion to the distance: as a rule of thumb, a few easy days after a 10 km, one to two weeks or more after a marathon or long-course race.

The science behind it

Optional reading: the key studies, condensed.

Where block periodisation comes from. Issurin's review argues the traditional model has limits for high-level athletes: mixed training can produce conflicting adaptations, long multi-target periods can cause excess fatigue, workloads spread across many targets may give too little stimulus, and it struggles with several peaks a season (1).

Easy most of the time. In Seiler's review of descriptive studies of nationally and internationally competitive endurance athletes training 10–13 times a week, about 80% of sessions were at low intensity and about 20% included high-intensity work, used throughout the training year (8). That counts sessions, not minutes, so the split by time spent at each intensity can look quite different.

Pyramidal or polarised? A systematic review of ten studies found highly trained and elite distance runners typically train "pyramidal" (most training easy, a fair amount at threshold, a little very hard). The authors recommend shifting towards "polarised" (easy and very hard, little in between) for competition, a recommendation rather than a tested result (9). Both reviews describe athletes training far more than most amateurs.

What this means for amateurs. A network meta-analysis of 13 studies found no overall difference between polarised and pyramidal training for VO2max or time-trial performance. A subgroup analysis suggested recreational athletes (regular trainers, not beginners) may improve VO2max more with pyramidal training and competitive athletes more with polarised; that difference was for VO2max, not time-trial performance (10). It's a hint rather than a rule, but it fits with keeping some threshold work in an amateur's base and build.

How much a taper is worth. Mujika and Padilla's review concluded that a taper typically improves performance by about 3%, within a usual range of 0.5–6%, and that progressive tapers beat sudden ones (4). The 2023 endurance meta-analysis found time-trial performance improved while VO2max did not clearly change from before to after the taper, and that one-step tapers could also work (3). Both draw mainly on trained athletes, so treat the 3% as a sense of scale.

Block periodisation. The meta-analysis pooled six studies and found small benefits for VO2max and peak power in a ramp test; performance outcomes weren't pooled, and the narrative part of the review reported moderate to large effects there, from similarly small studies of low to medium quality (5). In a 12-week study of 15 well-trained cyclists, the group that repeated a cycle of one week with five interval sessions, then three weeks with one each, improved VO2max by about 9%, against about 4% for two interval sessions every week, with similar total training (6); the sample was small. A later load-matched study of 30 trained cyclists (26 completed the performance tests) found both groups improved 5- and 40-minute time-trial power by about 8–9%, with no difference between them, and VO2max changed in neither group (7). Much of this research comes from one group: Rønnestad is an author on all three papers, and his group ran four of the six pooled studies, so be cautious.

A healthy dose of doubt. Kiely argues periodisation theory rests partly on an old model of stress, and that adaptation also depends on life stress, emotion and how an athlete perceives training (11). His conclusion is not to abandon planning but to treat a plan as a starting point you adjust.

References

1. Issurin VB. New horizons for the methodology and physiology of training periodization. Sports Med. 2010. doi:10.2165/11319770-000000000-00000
2. Bosquet L, Montpetit J, Arvisais D, et al. Effects of tapering on performance: a meta-analysis. Med Sci Sports Exerc. 2007. doi:10.1249/mss.0b013e31806010e0
3. Wang Z, Wang YT, Gao W, et al. Effects of tapering on performance in endurance athletes: a systematic review and meta-analysis. PLoS One. 2023. doi:10.1371/journal.pone.0282838
4. Mujika I, Padilla S. Scientific bases for precompetition tapering strategies. Med Sci Sports Exerc. 2003. doi:10.1249/01.mss.0000074448.73931.11
5. Mølmen KS, Øfsteng SJ, Rønnestad BR. Block periodization of endurance training – a systematic review and meta-analysis. Open Access J Sports Med. 2019. doi:10.2147/oajsm.s180408
6. Rønnestad BR, Ellefsen S, Nygaard H, et al. Effects of 12 weeks of block periodization on performance and performance indices in well-trained cyclists. Scand J Med Sci Sports. 2014. doi:10.1111/sms.12016
7. Almquist NW, Eriksen HB, Wilhelmsen M, et al. No differences between 12 weeks of block- vs. traditional-periodized training in performance adaptations in trained cyclists. Front Physiol. 2022. doi:10.3389/fphys.2022.837634
8. Seiler S. What is best practice for training intensity and duration distribution in endurance athletes? Int J Sports Physiol Perform. 2010. doi:10.1123/ijspp.5.3.276
9. Casado A, González-Mohíno F, González-Ravé JM, et al. Training periodization, methods, intensity distribution, and volume in highly trained and elite distance runners: a systematic review. Int J Sports Physiol Perform. 2022. doi:10.1123/ijspp.2021-0435
10. Rosenblat MA, Watt JA, Arnold JI, et al. Which training intensity distribution intervention will produce the greatest improvements in maximal oxygen uptake and time-trial performance in endurance athletes? A systematic review and network meta-analysis of individual participant data. Sports Med. 2025. doi:10.1007/s40279-024-02149-3
11. Kiely J. Periodization theory: confronting an inconvenient truth. Sports Med. 2018. doi:10.1007/s40279-017-0823-y