Threshold Pace, Endurance Swim Training, and Setting Race Pace

Hey everyone!

There were a couple questions in our mentor group about determining race pace, creating workouts, determining workout pace and rest periods, etc. I wrote an article that covers the basics. After reading it, a couple people in the group encouraged me to post it here in the main forum.

Please bear in mind as you read this – This post makes the general assumption that your stroke technique is good.  Technique trumps everything else and must be correct before you embark on a serious base build.  This post is only covering the basics. It does not discuss energy pathways other than to define ‘threshold,’ it does not cover periodization, it does not cover tapering for an ‘A’ race and it was written with the beginner or intermediate swimmer in mind. Remember, THERE IS NO REPLACEMENT FOR A PROFESSIONAL COACH IF YOU WANT TO EXCEL!  One other point, I am not a fan of drills so you will find no reference to drills when I get to talking about workouts (that is another discussion for another day).  If you are using drills, fins, or a lot of kicking, you would need to add that to your workout.

So, with that said, the post is VERY long. Hope you find it helpful.

When you are endurance swim training or are an athlete that participates in triathlons it is helpful to know your Swim Threshold Pace (STP). This post is not meant to be a discussion on energy pathways so I am going to define STP as the Maximal Lactate Steady State (MLSS), also known as Lactate Threshold (LT), or Individual Anaerobic Threshold (IAT). The important thing to understand is that STP is the highest possible steady-state work intensity (pace) you can sustain for an extended period of time, generally accepted to be 30-60 minutes.

As a practical matter, using blood tests in the wet environment of a swimming pool is a non-starter. However, there are a couple ways to determine your STP. The first is to do a long maximal effort time trial swim, typically 1,000 yards/meters and then determine your average pace per 100 over the final 400 of the swim. The problem with this method is that swimmers tend to go out too fast which skews the results to the low side, and it takes a good deal of time to recover from a 1,000 yard/meter swim. The second method is becoming the preferred method which is to use the modified Critical Swim Speed (CSS) test. The advantage to a STP/CSS test is that it can be done before a workout as it is quick and easy to administer plus it doesn’t replace a workout as a long time trial often does. The disadvantage is that it tends to produce a STP that is a couple seconds per hundred too fast. We can easily adjust for that when we set-up workouts and/or a race pace.

STP/CSS Test Procedure -

Do your normal warm-up (i.e. 200 easy freestyle). Once you are warmed up, you will do two time trials, one of 50 yards (or meters if you are in a long course pool) and one of 400 yards/meters. Both time trials will be at a maximal pace - meaning as fast as you can go the distance. There needs to be sufficient time between the two swims so that you are FULLY recovered before the second time trial. I recommend doing the 50 first as the recovery time is shorter. Ideally you will have someone available that can time you. If not, time yourself, the slight difference in time will not be significant. To start, push off from the wall - NO DIVING START. Record the time in seconds. I suggest an EASY 100 after the first swim to clear the lactic acid. Give it at least 10 minutes, then do an EASY 100. Then start the second time trial. Again, record the time in seconds.

How to Calculate STP/CSS -

STP/CSS/Threshold Pace in yards/meters per second can be calculated with the following formula, where D1 = 50, D2 = 400, T1 = time for 50 swim in seconds and T2 = time for 400 swim in seconds:

STP/CSS/Threshold Pace = (D2 - D1) ÷ (T2 - T1)

So now you have a couple numbers from your test. What do they mean and how can I use them?

We happen to have a couple of imaginary swimmers that just did the STP test.

Suzie Swimmer recorded 64 seconds (1:04) for the 50 yard time trial, and 592 seconds (9:51) for the 400 time trial.
Ricky Racer recorded 32 seconds for the 50 and 296 seconds (4:55) for the 400.

The STP calculations –

For Suzie – STP = (400-50) / (592-64) = 0.66 yards/second.
For Rickie – STP = (400-50) / (296-32) = 1.18 yards/second.

Now that we have our STP number, let’s take a moment and look at the various types of swim endurance training and use the STP numbers from the volunteers to see how to use STP.

There are different types of swimming endurance training –

Extensive Endurance – Long repetitions at a steady, comfortable pace.
Intermediate Endurance – Shorter repetitions that are closer to your race pace.
Intensive Endurance – Very hard efforts. For stronger swimmers this will be below your race pace.

EXTENSIVE ENDURANCE TRAINING

You should exclusively do this type of training at the beginning of the season during your base build and then maybe once a week during the season. This type of training uses long repetitions. However, long does not mean race distance. Repetitions of 200 are typical with perhaps an occasional set of 400 repetitions (no more than once every couple of weeks). At the beginning of base training or if you are a newer swimmer, repetitions of 100 work well to begin to build swim fitness.

The idea is to use repetitions of a distance that you find challenging but not maximal, with sufficient rest that you can repeat the effort. You should be able to keep your breathing under control. If a swimmer tries to swim too far or too fast in a single repetition, they would likely fade badly and their stroke technique would rapidly deteriorate. You do not want to train with poor technique!

An extensive endurance training session for Suzie, our newer swimmer might look something like this –

5 x 200 at a comfortable aerobic pace. This should be 10-15 seconds per 100 yards slower than your STP with approximately 45-60 seconds rest/recovery between repetitions. To determine the base pace take the target distance and divide by your STP.

Target Pace = (200 / 0.66) + 30 (add 15 seconds per 100 for extensive endurance pace) = 333 seconds = 5:33/200. From that, add your rest period, to arrive at an interval time. 5:33 + rest = 6:30 interval time. As your endurance increases, you begin to add repetitions. The goal is to build to a total distance of 1.5 – 2.0 times your longest race distance in the upcoming season.

The key to extensive endurance training is hitting your target pace – that’s what that big clock at the end of the pool is for! By the way, this will begin to teach you pacing which will benefit you on race day!

Now, let’s look at an extensive endurance training session for Ricky –

Ricky is more experienced so he will be swimming a longer workout – 10 x 200 at a comfortable aerobic pace with 45-60 seconds rest/recovery between repetitions.

Target Pace = (200/1.18) + 20 (add 10 seconds/100 for more experienced swimmer extensive endurance pace) = 209 seconds = 3:29/200. Add rest period for interval time – 3:29 + rest = 4:30 interval time.

When you are able to maintain good technique with steady controlled breathing for 1.5 – 2.0 times the longest race distance in the upcoming season on a regular basis, you have begun to develop a good endurance capacity for your speed . . . now it’s time to work on going faster.

INTERMEDIATE ENDURANCE TRAINING

This type of endurance training is used after you have achieved a basic level of swim fitness. The intensity you want for these training sessions is quite hard, although not an all-out maximal effort. The pace should be “uncomfortably comfortable.” Breathing should still be under control but in these sessions it is more difficult to maintain that control. Developing endurance at this pace and intensity helps with the latter stages of the swim and begins to develop speed.

Shorter repetitions are used for Intermediate Endurance Training with reduced rest periods.

An example of an Intermediate Endurance session using Suzie’s STP –

20 x 100 at STP with 15 seconds rest. As you become more proficient, add more repetitions.

Target pace = 100/.66 = 151 seconds = 2:31. Add 15 seconds rest for interval time = 2:45 interval.

As you progress through this set it will become increasingly difficult to maintain stroke technique and control your breathing. Newer swimmers should attempt less repetitions to avoid stroke technique deterioration.

INTENSIVE ENDURANCE TRAINING

This type of training isn't really endurance training in the true sense of endurance training . . . it is just HARD.  Intensive endurance training will develop speed and more importantly it is training your body to clear lactic acid from your bloodstream. This is a VERY HARD session and you need to be technically very competent to gain the most benefit. Otherwise you will find that your stroke technique will deteriorate as you fatigue and you will be missing interval times by increasingly wide margins.

The session might look something like this –

10 x 100 at 3-5 seconds below STP with 20 seconds rest.

This could develop into multiple sets in the same session.

2 x [10 x 100 at 3-5 seconds below STP with 20 seconds rest] and 5 minutes between sets.

Make no mistake, this is a MAXIMAL EFFORT!

The early part of this type of session you will feel pretty good because you are swimming a relatively short distance and have a sufficient rest period. However, by the time you get halfway through the set you will find that 20 seconds rest is barely enough to get your breathing back under control. By the last couple of repetitions you will be gasping for breath as you start the next rep!

For Ricky, our stronger swimmer, the set pace and intervals would look something like this–

Target pace = 100/1.18 = 1:25 – 0:05 = 1:20/100. Add 20 seconds rest = 1:40 interval.

PUTTING IT TOGETHER TO PLAN WORKOUTS

Your swim training sessions should include:

1. A warm-up (In addition to warming up paying particular attention to stroke technique is beneficial)
2. A main set (Target is 1.5-2.0 race distance)
3. Cool down

Prior to the beginning of the season the focus should be on building endurance so workouts should exclusively include Extensive Endurance Training.

Once endurance has improved to where the swimmer can comfortably swim at least 1.5 – 2.0 times the longest race distance of the upcoming race season while maintaining stroke technique and keeping breathing under control Intermediate Endurance sessions should be added each week.

Intensive Endurance sessions should be utilized once every other week and added once a week approximately 4-6 weeks before your ‘A’ race to develop speed. This type of session should be removed from your workouts 2 weeks before your ‘A’ race. This type of session is for stronger swimmers and will compare to a long time trial. It is not a session you will want to do or should do often.

A typical mid-season training week for a moderate ability swimmer might include one Extensive Endurance session, one mixed Intermediate Endurance and Extensive Endurance session, and one Intermediate Endurance session.

As the swimmer progresses, he/she may add Intensive Endurance sessions as I described earlier.

RACE PACE

The final piece of the puzzle is determining race pace from your STP.

If you are a new swimmer or one that does less than 3 swim sessions per week, or you are not training sufficient yardage based on the 1.5-2.0 time race distance formula, your race pace will be the same as your STP. Simply divide 100 by your STP to determine your pace per 100 = 100/0.66 (Suzie's STP) = 151.51 seconds = 2:31.2/100. To predict your race swim time, take the total race distance and divide by your STP. Thus Suzie’s predicted time for the swim in a Sprint Triathlon (750 yards – I know it is actually 750 meters but for our example this is close enough) would be 750/0.66 = 1136.36 seconds = 18:44.8
For a more experience swimmer, you will learn through Intensive Endurance training sessions if you can do a Sprint Triathlon below STP. For any distance above a Sprint your race pace would be the same as your STP.

So there you have it. The basics to plan your workouts, or at least a bit of information to begin to understand what your coach is having you do.

Happy swimming!