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Swimming · 8 weeks8-week open water mile training plan
An 8-week open water mile training plan takes a swimmer who does 400 m in 7:30, about 4 km a week from where they are to race day in 9 weeks, building to 2h23 of training in the biggest week. It spends 6 weeks in build, 2 weeks in peak, with 1 lighter week to absorb the work, on 6 days a week.
Build my open water mile plan — freeBuilt from your own numbers and your own week. The first week is free.
8 weeks is a comfortable length for an open water mile. At this distance a separate base phase is not needed — the plan builds steadily from the first week, with a lighter week to absorb the work and time to arrive fresh.
How long the open water mile takes
Predicted open-water time over 1.6 km, by Critical Swim Speed. Open water is slower than the pool — no walls to push off, sighting, and a line that is never quite straight — and the prediction allows for it.
| Your CSS per 100 m | Predicted finish |
|---|---|
| 1:35 | 26:51 |
| 1:45 | 29:41 |
| 2:00 | 33:55 |
| 2:15 | 38:10 |
| 2:30 | 42:24 |
Over a mile the start decides a lot. A mass start is chaotic, and thirty seconds lost starting wide and clear is cheaper than the minutes lost to panic in the pack. Sight every six to eight strokes.
What the weeks are for
| Build | 6 weeks — the harder sessions arrive and volume keeps climbing |
|---|---|
| Peak | 2 weeks — the biggest, most race-specific weeks |
| Lighter weeks | 1, roughly every fourth week |
| Total | 25 hours |
The 9 weeks
Generated for a swimmer who does 400 m in 7:30, about 4 km a week.
| Week | Phase | Hours | Load | |
|---|---|---|---|---|
| 1 | Build | 3h 18 | 96 | |
| 2 | Build | 3h 18 | 96 | |
| 3 | Build | 3h 18 | 96 | |
| 4 | Build · down | 2h 37 | 52 | |
| 5 | Build | 3h 18 | 96 | |
| 6 | Build | 3h 18 | 96 | |
| 7 | Peak | 2h 23 | 101 | |
| 8 | Peak | 2h 23 | 101 | |
| 9 | Race · race | 1h 05 | 73 |
The biggest week, session by session
Week 7, peak phase — the heaviest week of the block.
| Monday | Technique and drills — 0h35, 2 km |
|---|---|
| Tuesday | Open water — 0h44, 2 km |
| Sunday | Strength — lower body — 0h27 |
| Sunday | Speed — 8 × 100 m — 0h37, 1.8 km |
The swim paces
| Critical Swim Speed | 1:59 per 100 m |
|---|---|
| Recovery | 2:09/100 m — Easy enough to think about your stroke rather than your lungs. |
| Endurance | 2:04/100 m — Steady. You could keep going for a long time. |
| CSS | 1:59/100 m — Threshold. Hard but repeatable across a whole set. |
| VO₂max | 1:56/100 m — Faster than threshold, in short reps with real rest. |
| Speed | 1:53/100 m — Short and quick. Technique first, effort second. |
From a 400 m in 7:30 and a 200 m in 3:32, using the two-trial protocol (Wakayoshi et al., 1992). Your own CSS comes from your own two swims.
What this plan says out loud
Worth saying plainly about swimming: for most amateur swimmers, improvement comes from technique rather than fitness. This plan can prescribe the work. It cannot see that your hips are sinking or your catch is dropping, and no amount of threshold sets fixes a stroke. If you can afford one thing, buy a few sessions with a coach on the pool deck rather than more sets from us.
You are starting from a low base, so the first few weeks are deliberately modest. Consistency now is worth more than any single session.
Some sessions have been cut to fit the time you said you have — 45 minutes on a weekday and 60 at the weekend. That is a real constraint and the plan respects it, but be aware the long session is the one that matters most: if you can find more time anywhere, find it on the weekend.
Common questions
Is 8 weeks enough for an open water mile?
Yes, for most people who already exercise. We would choose at least 8 weeks, and this is 8.
How many days a week does it train?
6, on Monday, Tuesday, Wednesday, Friday, Saturday, Sunday in this example. You tell the plan which days you actually have, and it never puts two hard days back to back.
What is the longest session?
Open water, about 0h44. It is capped by share of the week, by absolute length, and by the time you say you have.
Can I use this if I train at altitude?
Yes, and you should say so when you build it. Paces and power are corrected for the difference between where you tested and where you train — in Johannesburg that is roughly 8%, or about 26 seconds a kilometre on an easy run for a 20-minute 5 km runner.