Understanding Base

Understanding Base

Coach Pat’s workouts are based on using a “base” time for most of the main sets as well as IM, stroke, kick and pull sets.  We sat down with Pat to ask her what is this mysterious base and why does she think it is so important to your training (and she does think it is very important) Here is what she had to say:

What is base?

Base is short hand for your “aerobic threshold base interval” or the speed you can swim over a long distance (at least as long as your longer main sets).   There are two kinds of speed. We all think about how fast can you go. The second is how long you can go that fast.  We use this second type of speed to create a base interval. Now that you have a definition let’s look at base in general use.

This is important to your ability to hold pace in longer races (anything over 100 – 200 yards)

Turn into question General Use

The base is a time you are allotted to swim and rest for each 100 yards. If your base is 2:00 you must swim 100 yards and take your rest inside the time.  When you reach the 2:00 mark you start the next 100 yards. Repeat until the set is done.

If the set is longer than 100 yards, simply use the multiple. Using my 2:00 base here is the time I would do for longer, or shorter distances:

Distance                           Time

50 1:00
75 1:30
100 2:00
150 3:00
200 4:00
250 5:00

Now that you understand what it means and how to use it, I’d like to share just a snippet of what makes it important.

Why is base important?

When you focus on doing your sets on rest intervals, defined as a specific predetermined amount of time, it is very easy to slip into getting slower, and slower.  When you swim on a specific interval say 2 minutes per 100 yards (just to keep the math easy), you will get more rest when you work harder, and less rest when you don’t.  This will force you to maintain your pace.  I’m not saying it’s easy, but it is what you need to do to improve.

Staying on base intervals vs. rest intervals will help maximize the benefit from the time invested.  This is why you see most of my work sets on intervals.  This concept is less important when swimming warm ups, warm downs, presets, and drill sets.  These sets have a different purpose, but that’s a different conversation.

So now we need to determine your base.

How to determine your base?

You are going to do a swimming “test set” followed by a “confirmation set”.  Let me walk you through the steps:

Step 1: Determine how long your set will be:

  • What is the length of your typical main set?
  • Select the set from the list below that comes the closest to the total yardage you swim in your main set. Make sure your selection presses towards your normal maximum yardage.
5X100 10 sec RI
3×200 15 sec RI
4×200 15 sec RI
3×300 20 sec RI
4×300 20 sec RI
5×300 20 sec RI
6×300 20 sec RI
7×300 20 sec RI
8×300 20 sec RI
9×300 20 sec RI
10×300 20 sec RI


Step 2: Swim your set

Now do the selected set.  Be careful to be accurate on counting and rest.  I’ve had swimmers tell me, “I did it on more rest, because I could be faster.”  Well of course, everyone is faster if you get more rest.  That is not the point. To determine your aerobic threshold you must get minimal rest to stay aerobic.

Step 3: Doing the math

Once you are finished, perform the following math:

Instructions Example (3×300 on 20 sec RI)
Take your total swim time (including the rest)


Multiply the minutes by 60 and add the seconds. (this is converting a minutes:seconds time into all seconds) 13×60= 780

780 + 06 = 786 seconds

Subtract your rest time to get a total of time spent swimming 786 – 40 = 746
Divide by the number of 100 yards (i.e if your set was 900 yards long divide by 9) 746/9= 82.88
The answer will be the time you averaged for each 100 yards. (This is your threshold time, or the time you can average over the distance) 82.88 seconds or 1:22.88 seconds per 100
Round up to the nearest 5 second increment 1:25
To get your threshold interval add the following amount to your time

  • For times under 1:40 (100 seconds) add 5 seconds
  • For times between 1:41 and 2:00 (101 -120 seconds) add 10 seconds
  • For times between 2:01 and 2:30 (121 – 150 seconds) add 15 seconds
  •  For times over 2:30 (151 and above seconds) add 20 seconds

This time is now your  starting“base” interval time


Step 4: Now for the Art

Now that you have determined your base interval using the Threshold test set you will do a confirmation set (not in the same workout)

The confirmation set is to repeat the same set a second time, replace the rest interval with the base interval you determined.  If you can’t make the set add 5 seconds to the interval and try again, next work out.  If you are sitting around enjoying copious amounts of rest reduce the interval by 5 seconds.

Non Free base

This same concept can be used to determine a kick, IM, stroke, or pull threshold as needed to have a complete set of base intervals.  Keep in mind that the total yardage done of these nonfree alternatives is generally shorter than your free sets so go back to step 1 and select appropriate distances for these nonfree threshold test sets.