Intensity Guidelines for Swimming
by Leyla Porteous
We recommend also reading Understanding Your TrainingPeaks Structured Workout Plan after reading this article.
Your 80/20 Swim plan employs a seven-zone intensity scale. Performing each workout and workout segment at the right intensity is at the heart of 80/20 training. This article provides all of the information you’ll need to determine your intensity zones so you can monitor your intensity during workouts and ensure you’re always in the right zone.
The short version. 80/20 swimming uses seven pace zones set from your threshold swim pace, which swimmers and Garmin call critical swim speed, or CSS. To set them you do three things.
- Warm up, then swim 400 meters or yards as fast as you can and record the time.
- Rest a few minutes, then swim 200 meters or yards as fast as you can and record the time.
- Enter both times in the 80/20 Zone Calculator and your threshold pace per 100 and seven zones appear.
The rest of this page explains the test, the arithmetic behind it and an alternative test.
Your personal intensity zones can be automatically calculated based on the protocols described below at the 80/20 Zone Calculator or directly in TrainingPeaks.com using the steps outlined in the document Understanding Your TrainingPeaks.com Structured Workout Plan.
Swim Pace
Pace is the most useful intensity metric for swimming and the metric that all of our swim workouts are structured with. Your seven custom swim pace training zones are based on your swim pace at lactate threshold intensity. The best way to find your lactate threshold pace in the water is with something called the critical velocity test. It’s fairly simple: Go to the pool, warm up with some easy swimming, and then swim 400 meters or yards as fast as you can, recording your time. Rest for two minutes to several minutes and then swim 200 meters or yards as fast as you can, again recording your time.
After your test, use the zone calculator or use the 80/20 auto-calculation directly in your TrainingPeaks Zone settings to determine your swim zones. Alternatively, you can calculate your threshold swim pace based on the following formula:
Critical velocity (CV) = (400 meters/yards – 200 meters/yards) ÷ (400 time – 200 time)
Let’s look at an example.
Suppose you swim your 400-yard test in 4:21 (4.35 minutes) and your 200-yard test in 2:02 (2.04 minutes).
Your critical velocity, then, is (400y – 200y) ÷ (4.35 min. – 2.04 min.) = 86.6 yards/min. However, it is customary to express critical speed in the form of time per 100 yards.
To make this conversion, divide 100 by your critical velocity. In this example, 100 ÷ 86.6 = 1.15. So your lactate threshold pace per 100 yards is 1.15 minutes, or 1 minute and 9 seconds.
A mathematician will notice that the CV formula result is influenced both by the time and the delta between the two tests. Even if your total combined 400+200 time goes down from test A to test B, if the difference between the 400 and 200 times is greater in test B, your CV might increase. In this way, the CV test "punishes" the athlete for poor pacing.
Some swimmers therefore may have a difficult time with the CV test. An alternative test is the 1,000 yard time trial. Swim 1000 yards (or meters) as fast as you can. Your average pace per 100 is your lactate threshold swim pace.
If a test result looks off, ask Mind of Matt whether to trust it or test again.
Your seven swim zones as percentages of threshold speed. A higher number is faster, so Zone 1 is the slowest band.
| Zone | Pace, % of threshold speed | Example at 1:40 per 100 |
|---|---|---|
| 1 | 75 to 84 | 2:13 to 1:59 |
| 2 | 84 to 91 | 1:59 to 1:50 |
| X | 91 to 96 | 1:50 to 1:44 |
| 3 | 96 to 100 | 1:44 to 1:40 |
| Y | 100 to 102 | 1:40 to 1:38 |
| 4 | 102 to 106 | 1:38 to 1:34 |
| 5 | over 106 | faster than 1:34 |
The calculator does the arithmetic for you and prints your own paces.
Frequently asked questions
What is critical swim speed?
Critical swim speed, or CSS, is the same thing as the critical velocity described above. It is the pace you could hold for roughly 1,500 meters at a steady effort, worked out from a 400 and a 200 time trial, and it is the threshold that all seven 80/20 swim zones hang from.
Is the Garmin CSS test the same test?
Yes. Garmin's critical swim speed workout uses the same 400 and 200 protocol and the same formula. The pace per 100 it reports is your threshold swim pace, so you can enter your two times here and get the same number with your 80/20 zones attached.
What is a good critical swim speed?
It depends on your background. Many adult-onset swimmers start above 2:00 per 100 meters, strong age-group triathletes sit around 1:30, and the number matters less than the trend. Train in the right zones and retest.
Do my zones change between yards and meters?
Yes. Zones are specific to the pool you tested in. Paces per 100 yards are roughly 10 percent faster than paces per 100 meters, so retest or adjust when you change pools.
How often should I retest?
Every third or fourth week is ideal, and 80/20 swim and triathlon plans schedule a swim time trial for this. Retest sooner if your usual zone paces start to feel easy.
Do I need a swim watch?
No. A pace clock and the two recorded times are enough. A watch makes it easier to hold a zone during long sets.
Keeping Your Zones Current
As your fitness level changes, you will need to adjust your zones to keep them current.
Many athletes like to update their zones on a regular schedule. If you wish to do so, choose a preferred testing method from above and repeat it during every third or fourth week beginning with the first recovery week of your plan.
After each test, enter your new numbers in the 80/20 Zone Calculator to update your zones.
Runners, cyclists and triathletes have their own guides. See the intensity guidelines for running, cycling and triathlon, and the training intensity articles for the science behind the zones. Every 80/20 swim plan and triathlon plan applies these zones for you, and Team 80/20 includes them all.