Threshold Series Part 3: How To Find Your Swimming Threshold Via T-30

If you want to strike fear into the swimmer’s heart, just say the words, “T-30” to them. If you’ve done one, you know. If you haven’t… you’ll understand. A T-30 is a type of test set used to find a swimmer’s threshold pace. It is not the only way to determine an athletes threshold, but it is a VERY accurate way. I think T-30’s are better suited towards intermediate and advanced swimmers. If you don’t fit into the advanced or intermediate category do not worry. I’ll have suggestions for you in a subsequent post.

Rules: To swim a T-30, the swimmer will swim at the fastest pace they can hold for thirty minutes without stopping. At the end of thirty minutes, divide 30 minutes by the amount of yardage covered. If the swimmer has completed 12.5 yards or more when thirty minutes is up, give them the 25 they are on. If the swimmer is less than 12.5 yards when thirty minutes is up, don’t give them the 25.

Example 1: A swimmer completes 1,000 yards during their T-30. 30/10 = 3:00 per 100

Example 2: A swimmer completes 2,450 meters during their T-30. 30/24.5 = 1.22 or 1:13 per 100

Example 3: Time stops after a swimmer has flipped at the 925 meter mark but before they’ve swam 950 meters. They have made it just over the halfway point (937.5 meters) in thirty minutes. Round up to 950 meters as they’ve swum passed the 12.5 meter mark during the T-30. 30/9.5 = 3.16 or 3:10 per 100

Example 4: Time stops after the swimmer has pushed off the wall at the 925 meter mark but before they make it halfway through the 25. Find their threshold using 925 yards. 30/9.25 = 3.24 or 3:14 per 100

Great, now that we’ve got the swimmer’s threshold pace we can figure out how to apply it to a workout. In general, if the athletes is swimming more than 400 to 500 yards, they’ll want to be right on or close to their threshold pace during the set. If they are swimming less than 400 to 500 yards continuously (i.e it is broken into a shorter duration) they’ll want to be a little faster than their threshold pace to compensate for the rest interval they are getting. i.e, swimming a shorter duration with rest at the same pace as their T-30 threshold isn’t as challenging as swimming a further distance continuously because they get to rest between repeats.

Sometimes you’ll see workouts written with T-Pace or Cruise pace with minus sign next to it, “T-Pace -:02 or Cruise -:03” when distances are shorter and should be faster. When threshold is designated as EN2, as I’m more familiar with, the effort is implied. You can also see them with a plus sign next to them, like “T-Pace +:10 or Cruise +:05” when the pace should be slower than their threshold. In that case, EN2 is not used to describe the pace but another energy system.

Lets take the swimmer from Example 2, above. Their threshold pace is 1 minute and 13 seconds per 100. If they are swimming a set like this:

4 x 400s EN2 @ :10 rest

Their goal time will be around 4:52 per 400 and their interval will be rounded to 5:05.

Let’s take that same swimmer from Example 2 and give them a set like this:

15 x 100s EN2 @:20 rest

Their goal time might be around 1:11 per 100 and their interval would be 1:30.

Now, lets mix things up for the swimmer from Example 2 even more and give them a set like this:

3 x 300s EN2 @ :10 rest
2 x 100s smooth @ :05 rest
4 x 400s EN2 @ :20 rest
2 x 100s smooth @ :05 rest
5 x 500s EN2 @ :30 rest

Their goal time for the 300s would be around 3:33 with an interval of 3:45. Their 400s would be around 4:52 with an interval of 5:15. Their goal time for their 500s would be around 6:07 and their interval would be 6:35.

Tip: When determining intervals, round to the nearest :05. If you’re coming in on a :01 or :02, round down. If your’e coming in on the :03 or above, round up.

Tip: I say times should be “around” a certain pace because threshold can be affected by how an athlete feels that day. You have to learn to trust your gut and swim at a pace that feels right for you. I was a sprinter, so I always went faster than my threshold pace said I should. I could maintain a faster speed for shorter distances but I would slow down over longer ones. A distance swimmer, like my fellow waterblogger, Vicky, could hold her threshold pace forever.

Up Next: A Taste of My Own Medicine: My T-30

Categories: Test Sets, Threshold Pace

Tags: , , , , ,

5 replies

  1. Great info and I’m excited to give it a try (although 30 minutes will definitley be a stretch at this point).

  2. I’m glad a read this, but even more glad I’m a novice and not yet intermediate or advanced! Excellent post though. Thanks.


  1. Threshold Series Part 2: Who Should Know Their Swimming Threshold Pace | The Water Blogged Triathlete

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