Swimming

Tempovi coaches swimming the same way it coaches your other cardio: it reads your recovery and training load, then writes a session for today and sizes the week. This page covers setting it up, the swim-specific numbers (time in water, Critical Swim Speed, sTSS, SWOLF) and how to get swims from an Apple Watch or a Garmin.

Set Swimming as your main sport

1. Open Settings › Profile & Goal › Main sport.
2. Choose Swimming.

Home then opens on the Swim tab. Its five tiles are distance (m), time, number of swims, pace per 100 m and average heart rate. Tap any tile to open Swim progress.

Other main sports are Running, Walking, Dancing, Cardio and All. Your choice only decides which tab Home opens on and which sport the coach writes sessions for. Every sport tab stays available, and strain, cardio load and Body Battery already count all your workouts.

What the coach writes

The Daily Coach and the 7-Day Plan size each day exactly as before, from readiness, recovery, training load and a rolling 7-day volume budget with a weekly growth cap. What changes is how the session is written. For swimming it is a pool session:

• a warm-up
• a main set, in 100–200 m reps or as continuous metres
• a cool-down

The distances are sized from your swim pace. Once you have set your Critical Swim Speed, the targets come from that instead.

Swim sessions are not affected by outdoor heat, because you swim in a pool.

Note

Tempovi doesn’t send swim workouts to your watch. The watch workout push is for running only. Take the session from the Daily Coach and start a pool swim in Apple’s Workout app (or your Garmin) as usual.

Time in water: your volume budget

Runners are limited by time on feet. For swimmers the same rolling volume budget is counted in time in water (TiW): your swimming time without the rests between sets. This is what keeps a week of hard intervals from being counted as if you had swum non-stop.

• Apple Watch swims and imported FIT files contain the lengths, so Tempovi can tell swimming from resting.
• A Garmin swim that reached Apple Health has totals only. In that case the whole session time is used.

Walking, dancing and cardio use their plain session minutes.

Critical Swim Speed (CSS)

Critical Swim Speed is the fastest pace you could hold for a long time without tiring quickly: close to your threshold pace in the pool. It is the base for your swim targets.

How to test

Do two time trials: a 400 m and a 200 m, each as fast as you can hold evenly from start to finish. Warm up properly first. Rest a few minutes between the two, or do them on separate days.

Then enter both times: Settings › Training › Swimming › Critical Swim Speed.

The formula

CSS pace per 100 m = (T400 − T200) ÷ 2, with both times in seconds.

For example, a 400 m in 6:40 (400 s) and a 200 m in 3:00 (180 s) give (400 − 180) ÷ 2 = 110 s, so a CSS of 1:50 per 100 m.

How the targets use it

Effort	Target pace per 100 m
Easy	CSS + 10–15 s
Steady / threshold	CSS ± 2 s
Hard reps	CSS − 3–5 s

With a CSS of 1:50, easy swimming is about 2:00–2:05, threshold is about 1:48–1:52 and hard reps are about 1:45–1:47.

Without a CSS test, Tempovi uses your typical pace from recent swims. That works, but a test makes the targets more accurate.

Tip

Your CSS changes as you get fitter. Re-test every 6–8 weeks.

sTSS: swim training stress

When CSS is set, every swim shows sTSS (swim training stress score). It tells you how demanding the swim was, on the same scale idea as running TSS: one hour at your CSS pace is about 100.

1. IF (intensity factor) = your CSS pace ÷ the swim’s moving pace. Both are in seconds per 100 m, so swimming faster than CSS gives an IF above 1.
2. sTSS = IF³ × hours × 100.

IF is cubed because water resistance rises steeply with speed: swimming a little faster costs a lot more effort. The method is the one TrainingPeaks uses for swim TSS.

For example, 1,000 m at a moving pace of 2:00 per 100 m is 20 minutes of swimming. With a CSS of 1:50, IF = 110 ÷ 120 ≈ 0.92, so sTSS ≈ 0.77 × 0.33 × 100 ≈ 26.

SWOLF and stroke efficiency

SWOLF is the seconds plus the strokes it takes you to swim one length. A 20-second length with 16 strokes scores 36. Lower is more efficient.

• Compare SWOLF only between swims in the same pool length. A 50 m pool gives higher numbers than a 25 m pool.
• SWOLF is most useful as a trend: the same effort with a falling SWOLF means better technique.

Behind SWOLF is a bit of swim science. Your speed is stroke rate × distance per stroke. You can swim faster by turning over more quickly, by getting more distance from each stroke, or both. Tempovi shows strokes per length and SWOLF rather than the two components separately, but if your SWOLF improves because the stroke count drops, that is the distance-per-stroke part getting better.

Heart rate in water

Heart rate is usually lower in water than on land for the same effort. In one study, triathletes reached a maximum of 174.8 bpm swimming against 188.6 bpm on the bike (Roels, Millet et al. 2005). The horizontal position, water pressure and cooling all play a part. Tempovi therefore scores swims against a maximum about 12 bpm below your land maximum.

Tempovi uses heart rate for training load in every sport. So don’t compare a swim’s heart rate with run zones: compare swims with other swims.

Which muscles a swim trains

Swimming counts toward your muscle load in Strength, by stroke:

• Freestyle and backstroke — mainly lats, shoulders, triceps and upper back.
• Breaststroke — more chest, adductors and quads.
• Butterfly — the most shoulder- and core-heavy.
• Kick sets — legs only.

Getting your swims into Tempovi

Apple Watch

A pool swim recorded with the Workout app is fully automatic. Apple Health holds the lengths, strokes, stroke type and sets, and Tempovi reads them all.

Garmin

1. In Garmin Connect, open Settings › Connected Apps › Apple Health.
2. Switch on Workouts, Distance and Heart rate.

Only swims after you connect are copied. The copy in Apple Health has totals and heart rate, but no lengths.

For the full detail, import the swim’s FIT file:

1. In Garmin Connect, open the swim and tap ⋯ › Export Original (.fit).
2. Share the file to Tempovi (Open in Tempovi), or save it to Files and tap Import a Garmin FIT file at the bottom of Swim progress.

The imported swim replaces the totals-only copy. We are exploring automatic full Garmin sync — tell us you want it on the public tracker.

Swim screens

Swim progress

Tap a tile on the Swim tab. It shows:

• Pace per 100 m over time, with the trend in seconds per 100 m per month
• SWOLF over time
• Weekly distance
• a list of swims, and a time-window bar to change the period

Swim detail

Tap a swim to see its distance, time, pace per 100 m, average heart rate, pool length, main stroke, SWOLF, strokes, and swimming versus rest time. Below that:

• Sets — lengths × stroke, metres, time, pace per 100 m, SWOLF and the rest after each set.
• Lengths — number, stroke, seconds, strokes and SWOLF for every length.
• a heart-rate chart.

Swims imported from a FIT file show the same detail.

Share swim data with support

If a swim looks wrong, use Share swim data with support. It sends the structure of your last 5 swims (no names or locations), which lets us see how the file was laid out. See Troubleshooting.

Sources

• Critical swim speed: Wakayoshi et al. (1992), Determination and validity of critical velocity as an index of swimming performance, Int J Sports Med 13:367–371 (doi). The two-distance 200/400 m version is in Wakayoshi et al. (1993) (record).
• Swim TSS (IF³): TrainingPeaks, Calculating swimming TSS score.
• Heart rate in water: Roels, Millet et al. (2005), swimming vs cycle ergometry in triathletes and swimmers. Also Millet, Vleck & Bentley (2009), Physiological differences between cycling and running, Sports Med 39:179–206 (record).
• Energy cost without heart rate: the 2024 Adult Compendium of Physical Activities (pacompendium.com).