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How to read a swim workout: reps, send-offs and abbreviations

You open a workout and see lines like "4 x 100 free @1:50" or "8 x 50 kick, 20 s rest". It looks like code, but there are only a handful of rules and they never change. This guide goes through them one by one, then puts them together in a full sample workout, first in notation and then in plain words.

Repeats and distance: what 4 x 100 means

The first number is how many times you swim, the second is the distance of each. 4 x 100 is four repeats of 100 metres, 400 in total. 8 x 50 is eight repeats of 50 metres, also 400 in total. In a 25 m pool the numbers are almost always multiples of 25, so every repeat ends at the wall.

A single number, such as "400 free easy", is one continuous swim.

Send-off and rest: two ways to say how long to stop

This is where most confusion comes from. A workout can tell you how long to pause in two different ways.

Send-off (@1:50). The clock runs from the start of one repeat to the start of the next. Swimming and resting both fit inside it. On "4 x 100 @1:50" you leave every 1 minute 50 seconds. If you swim the 100 in 1:35, you rest 15 seconds. If you swim it in 1:45, you rest 5. The faster you swim, the more you rest. That is why you need a pace clock, or a watch with an interval timer.

Rest (20 s rest, R20). A fixed pause that starts when you touch the wall and ends when you push off. You always get 20 seconds, however long the swim took.

In practice, a send-off sets the rhythm for the whole lane, while a fixed rest lets you set your own. Many beginner workouts use fixed rest because it is easier to follow.

Strokes: free, back, breast, fly, IM

Most English workouts use these words or codes:

  • Free (FR): freestyle
  • Back (BK): backstroke
  • Breast (BR): breaststroke
  • Fly: butterfly
  • IM: individual medley, in the order fly, back, breast, free, a quarter of the distance each

Codes differ from coach to coach. If you do not recognise one, ask. It beats guessing.

Equipment and drills

  • Kick. You swim with your legs only, usually holding a kickboard in front of you.
  • Pull. You swim with your arms only, with a pull buoy between the thighs to keep your legs up. Hand paddles are sometimes added.
  • Fins. They add push from the legs and help body position. The workout says when to wear them.
  • Kickboard. A float that supports your upper body during kick sets.
  • Drills. Technical exercises that isolate one part of the stroke, such as swimming with one arm at a time. If a workout just says "drill", ask the coach, or look up which drill is meant.

The parts of a workout

Almost every workout has three blocks:

  1. Warm-up. Easy swimming before the real work, to warm the muscles and let breathing and heart rate rise gradually.
  2. Main set. The work the session is built around: repeats at a given pace with a given rest.
  3. Cool-down. Easy to moderate swimming at the end, to bring breathing and heart rate down.

Words that describe how to swim

  • Progressive (descending). Each repeat of the same distance is faster than the last. "4 x 100 descending" means the fourth 100 is the fastest. In a descending interval set it is the send-off that shrinks instead: for example 2:00, 1:55, 1:50, 1:45.
  • Negative split. The second half is faster than the first. In a 200, the second 100 is faster than the first.
  • Pace per 100 m. The time it takes you to swim 100 metres. If you swim 400 m in 7:20 (440 seconds), your pace is 440 divided by 4, which is 110 seconds, or 1:50 per 100 m. Pace helps you choose a send-off. For a reference pace built from your own times, read our article on critical swim speed.

A full workout in notation

Warm-up

  • 400 free easy
  • 4 x 50 (25 drill / 25 free) 15 s rest

Main set

  • 4 x 50 kick with kickboard, 20 s rest
  • 4 x 100 free @2:00, descending (4th is the fastest)
  • 4 x 50 pull, 15 s rest

Cool-down

  • 200 free easy

Total: 400 + 200 + 200 + 400 + 200 + 200 = 1600 metres.

The same workout in words

Warm-up. Swim 400 metres of easy freestyle, without watching the clock. Then four repeats of 50 metres: the first length (25 m) is a technical drill, the second is freestyle. Rest 15 seconds after each.

Main set. Legs first: four 50s with a kickboard, 20 seconds of rest. Then the main work: four 100s of freestyle, leaving every 2 minutes. Each one is a little faster than the previous, so the fourth is your strongest. If you swim the first in 1:50 you rest 10 seconds; if you swim the fourth in 1:42 you rest 18. Then four 50s of pull with a pull buoy, 15 seconds of rest.

Cool-down. 200 metres of easy freestyle to finish.

If you are just starting, begin with feel, not numbers. A workout swum well with extra rest beats one that falls apart halfway. For an example of how a beginner builds up, see the beginner swim workout plan.

Common mistakes

  • Mixing up send-off and rest. "@1:50" does not mean 1:50 of rest. It is the total time of the repeat, rest included.
  • Starting too hard. The first repeat of a set should not be the fastest, unless the workout says so.
  • Skipping the warm-up. It feels like lost time, but it lets you swim the rest better.
  • Skipping the drills. They are the dullest part and the one that improves your stroke most.
  • Not asking. A code you do not know is not your fault. Codes vary.

A plan that adapts

SwimSensei builds a plan from your level, the days you train and your pool length (25, 33 or 50 m), and adapts it every week. See how it works on the swimmers page and ask for early access.

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