Context
At Splits we built the swim block for recreational athletes with limited pool time: two or three sessions a week move the needle when they pair purpose with technique.
The numeric anchor is CSS — Critical Swim Speed, the pace you can sustain for roughly an hour. Once we have CSS we map out zones and pick which intensity belongs in each set. We spend most of the water time in zone 2 with technique drills woven in, because without an efficient stroke the aerobic engine leaks power. We pair it with shoulder and scapular strength twice a week, non-negotiable.
Methods
Three families inform the swim plans we're publishing. We picked them for the evidence behind them and for how well they fit athletes with limited weekly pool sessions.
Aerobic base with technique
Plenty of zone 2 and plenty of drills, with one harder set as the cherry on top. We use it as the base for newcomers and for athletes focused on sprint triathlon.
Three key sessions
One threshold session near CSS, one aerobic endurance set, and one technique-and-speed block. We like it for consolidated beginners on tight calendars.
Threshold-centered (CSS)
Long sets at CSS pace with short rests: 8×200 m or 10×100 m. We apply this for intermediates with a solid stroke chasing faster times.
How we derive the numbers
For the calculator's baseline times we anchor on CSS and on standard swim distances — 500 m, 1500 m, 3000 m, and 5000 m. Each level — new, beginner, intermediate — maps to a sustainable pace per 100 m for that distance. The table below shows the resulting times. We chose them conservatively on purpose.
| Distance | New | Beginner | Intermediate |
|---|---|---|---|
| 500 m | 00:15:00 | 00:15:00 | 00:10:00 |
| 1,500 m | 00:45:00 | 00:45:00 | 00:30:00 |
| 3,000 m | 01:40:00 | 01:40:00 | 01:00:00 |
| 5,000 m | 03:00:00 | 03:00:00 | 02:00:00 |
Sources
We back every decision with accessible literature. The four sources below are our primary references for swimming; we revisit them whenever we need to sanity-check a zone, a progression, or a shoulder strength routine.
- Phlex Swim Coaching Team — The Importance of Training Zones and How to Individualize Trainingphlexswim.comlink
- Scientific Triathlon Coaching Team — Triathlon Base Training Series 2 — Swimmingscientifictriathlon.comlink
- MySwimPro Coaching Team — Aerobic Zones vs. Power Zones: What They Mean for Your Swim TrainingMySwimProlink
- U.S. Masters Swimming Coaching Team — 5 Swimmer-Specific and Time-Efficient Exercises for Shoulder Healthusms.orglink
When it doesn't apply
These methods cover a recreational swimmer or an amateur triathlete with adequate technique. There are moments when it pays off to step outside the frame we propose; here's when, and why.
- They don't replace a coach who knows your stroke, prior shoulder injuries, and experience with threshold sets.
- If your stroke is still unstable, we suggest leaning on drills over intensity: the aerobic engine grows little when the catch falls apart under fatigue.
- For open-water swimming in extreme conditions (chop, cold, currents) pool-based models fall short: you'll swim slower than your CSS suggests.
- Any persistent shoulder pain when swimming needs medical evaluation and load adjustment before more training.