Session types

Steady State

Steady state sessions are long, continuous efforts at UT2 or UT1 intensity. The defining feature is that pace and Stroke Rate are held constant throughout — there are no intervals, surges, or rest periods.

What they develop: Aerobic base. Mitochondrial density, fat oxidation, cardiac efficiency, and the structural adaptations in muscle that support prolonged effort. These sessions form the bulk of a well-structured training program.

Typical structure: 30–90 minutes at a consistent split, with RPE around 2–4 out of 10. You should be able to speak in sentences throughout a UT2 session.

Threshold

Threshold sessions target the AT zone — the intensity at which lactate production and clearance are in approximate balance. Training at this level raises the pace you can sustain before lactate begins to accumulate.

What they develop: Lactate threshold, muscular endurance at race-relevant paces, and the ability to sustain hard efforts for extended periods.

Typical structure: 20–40 minutes of sustained effort, or broken into longer intervals (e.g. 3 × 10 minutes) with short rest. Effort feels comfortably hard — controlled but demanding.

Intervals

Interval sessions target the TR zone and develop VO2max — the maximum rate at which your body can consume oxygen. Efforts are short enough to be performed at high quality, with rest periods that allow partial recovery between repetitions.

What they develop: Aerobic ceiling, speed endurance, Power at high intensity.

Typical structure: 4–8 repetitions of 2–5 minutes at hard effort, with equal or longer rest. The work periods should feel genuinely hard but not maximal.

Sprints

Sprint sessions sit in the AN zone — all-out efforts lasting from a few strokes to around 90 seconds. These target anaerobic power and the neuromuscular recruitment patterns needed for race starts and finishing kicks.

What they develop: Peak power output, anaerobic capacity, and the ability to produce explosive efforts under fatigue.

Typical structure: Short repetitions (10–90 seconds) at maximum effort with long rest (3–5 minutes) between efforts. Volume is low; quality is everything. Sprint sessions appear infrequently in most programs given their recovery demands.