The basic format: reps × distance
Every set starts with two numbers separated by an x. The first number is how many times you do something. The second is how far each one goes.
4×100 free means four reps of 100 yards or meters, freestyle. If the stroke isn't named, assume free. If it says 4×100 IM, each 100 is a full individual medley — fly, back, breast, free, 25 of each.
The distance can be broken down further. 8×50 is not the same as 4×100 even though the total volume is equal. Shorter reps mean more starts, more turns, and usually a faster pace per 100 than the longer version.
The @ symbol: send-off interval
The @ sign tells you when the next rep starts, not how long you get to rest. This is the part that trips up parents and new assistants the most.
4×100 free @1:30 means a swimmer leaves on 0:00, 1:30, 3:00, 4:30. The interval is the total time allotted for one rep — swim plus rest combined.
If a swimmer holds 1:12 per 100, their rest is 1:30 minus 1:12, or 18 seconds. If they slow down and swim 1:28, they get almost no rest before the next one goes off. This is why coaches use send-off intervals instead of flat rest periods — the interval controls both pace and recovery at the same time, and it self-corrects. Swim faster, get more rest. Swim slower, get squeezed.
Some boards write @1:30 SO (send-off) to be explicit, or use :30 R to mean 30 seconds of pure rest with no set send-off. If you see 1:30 R, that's rest, not an interval — the next rep starts 90 seconds after the swimmer finishes, no matter their time.
Rounds and brackets
Sets often stack smaller pieces into rounds using brackets or parentheses.
3 rounds: (4×50 @0:45 + 200 @3:00)
This means do the bracket three times through: four 50s on 45 seconds, then one 200 on 3:00, then repeat that whole block two more times. Total volume: 3 × (200 + 200) = 1200.
A number in front of the bracket, or the word "rounds," tells you how many times to repeat everything inside it. Nested sets like this are how coaches build variety and mixed-energy work into one line instead of writing out forty individual reps.
Common instruction words
- Hold — keep the same pace across every rep. "Hold best average" means find a pace you can repeat for all four reps without falling apart on the last one. This isn't about swimming the fastest possible first rep — it's about picking a sustainable number and hitting it four times in a row.
- Descend 1-4 — each rep gets faster than the one before, across a set of four. Rep 1 easy-moderate, rep 4 fastest. A common mistake is descending too aggressively on reps 1-2 and having nothing left for 3-4.
- Build — get faster within a single rep. "Build 100" means start controlled and finish strong, all inside one length of the pool, not across multiple reps.
- Negative split — swim the second half of a rep faster than the first half. On a 200, that means the 100-150 and 150-200 are quicker than the opening 100. This is a pacing skill worth drilling directly, since most swimmers naturally go out too fast.
- DPS — distance per stroke. A DPS set asks for fewer strokes per length, not necessarily a faster time. Coaches use this to reinforce technique under low fatigue, often on easier intervals.
- RP — race pace. "3×100 free @2:00, RP" means swim each 100 at the pace the swimmer would hold in an actual 100 race, with plenty of rest to allow full recovery between reps.
- ! or max — all-out effort. No pacing strategy, just go. Usually reserved for short reps (25s, 50s) with generous rest so quality doesn't erode.
Reading a full set
Put it together and a whiteboard line like this stops looking like code:
3 rounds: (4×50 free @0:45, descend 1-4) + (1×100 free @1:45, RP) + 0:20 rest
That's three trips through a block. In each trip: four 50s on 45 seconds, getting progressively faster; then one 100 on 1:45 at race pace; then a short breather before starting the block again. A coach reading this instantly knows the energy system target (mostly aerobic-to-threshold, with a race-pace touch), the volume (900 total), and how to watch for breakdown — usually on rep 4 of the descend series or the RP 100 after fatigue builds.
Once you can parse reps, interval, rounds, and the instruction word, you can read any board in any pool, not just the ones you wrote yourself.
SwimIQ handles this translation automatically — feed it a spoken, photographed, or typed set and it breaks down the reps, intervals, and instructions into a structured plan, then flags which zone each piece actually trains so you can check the set against your own intent before you print it on the board.