How to Calculate Your Swimming Interval Timing for Improved Performance (2023)

Happy Sunday!

In today’s article, we will talk about the second most popular question among our readers: How do you calculate your interval timing in swimming?

Swimming interval timing is a crucial aspect of training for swimmers of all levels. It involves dividing a swim workout into timed segments, alternating between periods of effort and rest. What it means is that an interval time is used in swimming to know the time it takes to swim a distance AND your recovery. Let’s review the following example:

6 x 100 FR on 2:00 means this:

  • You have to swim 100 yards/meters Freestyle 6 times

  • Each 100 FR plus your resting time must be completed in 2 minutes.

So, if you swim the 100FR at 1:30, then you have 30secs to rest before you start the second 100.

Understanding how to calculate and utilize interval timing effectively can significantly enhance your swimming performance. In this article, we will explain in simple terms the methodology behind calculating swimming intervals and explore how incorporating them into the Daily Free Swimming Workouts can help you achieve remarkable progress in the pool.

Calculating Swimming Interval Timing

The most common method used to calculate intervals is based on your average pace per 100 meters or yards. Once you have your “100 base” for each stroke, it is easy to calculate intervals for all distances.

Let’s calculate your 100 base time for Freestyle.

Many coaches will differ slightly on how to calculate this time, however, the simpler way to do this is by swimming a 10 x 100 FR at a moderate pace with a rest time of 15 to 30 secs between 100s. The important part is to always track the time it takes to swim each of these 100s, and at the end calculate the average. Some people prefer to swim 1000 yards altogether and then divide the time by 10. Personally, I like better with short rests between, as you will end up with a more challenging base.

Why 10 times 100 yards/meters? The reason 10 rounds are important is that you will get tired as you swim them, and inevitably start slowing down. So, calculating an average provides us with the most reliable 100 base.

Do not confuse the base 100 time with your Personal Best time (or PB). If you swim a 100 all out in 1:15 in a race, that cannot be your base time target in practice. Can you imagine if 1:15 is your fastest time and the coach ask you to swim 10 x 100 on 1:15 in practice?

Why Using Swimming Interval Timing Improves Performance

The competitive swimming community use intervals for a reason. It is the simpler, best way to learn how much you are improving in your swimming, for every stroke. Let’s review the major benefits of swimming with intervals. I will add examples on each:

  1. Build Endurance: Swimming intervals can help you gradually increase your stamina and endurance. By challenging yourself to maintain a specific pace within each interval, you push your body to adapt and become more efficient. Over time, this leads to improved cardiovascular fitness and the ability to swim longer distances without fatigue.

    1. Practical explanation: When the set asks for 12 x 50s - (Rest 30sec between 50s), you might not know how much effort are you putting into each 50. Maybe you are swimming one 50 on 40 seconds and the next in 1min. then you still get 30sec rest as per the plan. For many of us lap swimmers, this is absolutely fine. in Contrast, if the plan says 12 x 50 on 1:00, then you know that no matter what you have to swim each 50 AND REST within every minute. It forces you to put the effort throughout the set.

  2. Enhance Speed: Interval training is an effective way to boost your speed in the water. By incorporating shorter, more intense intervals into your workouts, you can simulate race-like conditions and work on improving your sprinting abilities. These high-intensity bursts will train your muscles to generate more power and develop faster swimming techniques.

    1. Practical explanation: Assume we establish that your base 100 for Freestyle is 1:45. If you want to improve long-distance swimming and endurance, you can swim 10 x 100 at 2:00, which allows you to swim 1000 yards or meters almost continuously. As you make progress, you will realize that you have more time available to rest for each 100, so you would want to reduce your base. In contrast, if you want to improve speed for a 100 FR race, you could do the same 10 x 100 set but this time going fast in all 100s, and incrementing the interval to 3:00 gives you the time to rest and be ready to go fast again. Same philosophy in running, some days you go for a long run and never stop for 10km, and some days you do track speed work and run 5 x 200m and rest 3min. In swimming, we need both strategies also.

  3. Improve Technique: Focusing on swimming intervals allows you to pay closer attention to your stroke technique. When swimming at a consistent pace, you can concentrate on proper body alignment, a smooth catch, an effective kick, and a strong pull. This heightened awareness enables you to identify and correct any technical flaws, leading to more efficient and streamlined swimming.

    1. Practical explanation: You know you have to make the interval, and as such, you will want to use the best technique possible to make it.

  4. Mental Conditioning: Swimming intervals require mental fortitude as it motivates you to maintain a consistent pace for the set. Regular interval training helps develop mental toughness, teaching you to stay focused, push through fatigue, and overcome challenges. These mental skills are invaluable during competitive races and honestly in all aspects of life.

  5. Periodization and Progression: Interval timing allows for effective periodization and progression in your training. By adjusting the interval duration, intensity, and distance covered, you can systematically challenge your body and prevent plateaus. Gradually increase the difficulty of your intervals over time, pushing yourself to swim faster or cover longer distances within the same time frame. This is how we know we are improving.

How to use interval timing with the Daily Free Swimming Workouts

Because we are all so different, it would be impossible to recommend a generic interval for the daily swim workouts. Instead, I provide a “rest recommendation”, which by the way, is set on purpose, based on the objective for the day (Speed, endurance, etc).

So the way to use interval timing with the daily workouts is as follows:

First, calculate your 100 base for each of the strokes. You can fully replace a Main Set with the trial. Don’t do all 4 strokes on the same day, I recommend isolating each stroke to a single day. The recommendation is to swim 10 x 100 of the target stroke with 15 to 30 sec rest, at a moderate speed (Not fast, not slow). Memorize or better, write the time of each 100, and then calculate the average.

Say you calculated your base time for 100 yards Freestyle, and it is 1:20. Great job! Now, the 100FR on 1:20 is your new 100 base time, NOT the interval. The interval is your base time plus the rest time stated in the workout plan.

The requested set is: 6x100 FR (Rest 15sec between)

What will be your interval? Your 100 base: 1:30 plus the rest time of 15sec, which results in 1:35. So, for you the set is basically 6x100 on 1:35. Tadaaaaaaa!!!!

As you improve your swimming, your base time will decrease.

But coach, wait… Do I need a water resistance sports watch to check my base time and intervals?

Well, you could definitely use one, however, every swimming pool should (and notice I said “should”) have a clock/timer visible to all swimmers. Like the one below or digital also:

How to Calculate Your Swimming Interval Timing for Improved Performance (1)

If not available, there are many options out there from the Apple Watch (I use one) to Garmin (also have one) to Suunto, Timex, etc. That is maybe an article for another day.

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