Q: I have read your articles on Metrics-Tempo, Pace, etc with a lot of interest. What I was wondering, if you increase your DPS [distance per stroke], that means your SPL [strokes per length of pool] goes down. If SPL goes down, doesn’t that mean you will take less breaths in a minute? Won’t less oxygen impair the ability to swim longer distances?

I am probably missing something here, but would like your views


Here is my response:

Yes, longer DPS means a longer stroke, which means you take fewer strokes to get to the other wall, which means a lower SPL.
DPS = Stroke Length (SL)
SPL = # of Strokes Per Length of pool, or ‘Stroke Count’

If there were no other dimensions to breathing but just breathing in/out, then yes, longer strokes = longer span of time between breaths = more stress on the cardio-vascular system and less O2 for the muscles.

But breathing involves at least these three variables you have control over:
1) heart rate (an objective way to measure oxygen demand)
2) frequency of breathing (the breathing pattern)
3) quantity and quality of air exchange during the stroke cycle

When seeking to improve your DPS/SL the goal is not to make as long of a stroke as possible, but to reach an optimal stroke length.

Optimal Stroke Length = a small range of DPS/SL that is statistically shown to be our most efficient (in terms of using the least amount of energy, oxygen). This is approximately between 55% and 70% of your wingspan/height. Optimal SL doesn’t complete the speed efficiency equation but it sets up the first, and most important part.

#1 We first use technique improvement to lower O2 demand, primarily through removing struggle against gravity and remove excess drag from poor body shape and poor movement patterns. Reducing wasted effort – lowering energy waste – lowers the Heart Rate. Lower HR = Lower oxygen demand. And a lower demand for oxygen means the swimmer has more options for when breathe.

#2 Once a range of appropriate Stroke Length is developed the swimmer can adjust Tempo and adjust breathing pattern to maintain comfortably-frequent air exchange. A swimmer, especially in open-water, needs to be ready at any time to skip a breath if something prevents one and not feel much stress or desperation about it.

#3 And we work on actual breathing technique (exhale and inhale patterns) to improve exchange, trigger parasympathetic nervous system to lower HR, and thereby lower stress on the brain and body. How we exhale, where we exhale, how much we exhale and inhale- all that has an effect, and we can learn to control it and adjust it.

Let’s take a moderate Tempo of 1.25 and look at how different breathing patterns affect breaths/minute:

  • Pattern (Breaths / Minute)
  • 2-stroke (24)
  • 3-stroke (16)
  • 4-stroke (12)
  • 5-stroke (9)
  • 2-stroke + 3-stroke (19.2)
  • 2-stroke + 4-stroke (16)

Which one should you choose? You need to make that decision by what your body says it needs.

But for some reference point on what to aim for: I feel that a good indicator of achieving a basic level of swimming efficiency is to be able to swim comfortably with a 3-stroke breathing pattern in your  SPL Green Zone, and in the middle of your Tempo Comfort Zone. Coach Terry also uses a 3-stroke pattern as an ‘aerobic governor’ – if he can maintain a 3-stroke breathing pattern at a racing effort level that is his sign that he is holding in the aerobic zone. If that starts to feel inadequate he knows he is pushing into anaerobic zone. I agree with that guideline and use it myself. I breathe at such a pattern that allows me to skip a breath from time to time when I get smacked by a wave or something. I would switch to 2-stroke only in an anaerobic sprint and know I have limited time at that effort level.

Does that make sense or raise more questions?


To answer the shortest question:

How do I get enough breath while swimming?

  1. Lower heart rate by lowering your struggle against natural forces outside and tension inside the body.
  2. Increase the frequency of breathing, while decreasing that struggle.
  3. Improve your method of inhale and exhale.


The first product of technique training is to lower the demand for energy/oxygen. Speed is not the first product (it is the third one). The first obstacle is the struggle against gravity. When we quit struggling against gravity (achieving balance and lateral stability), we have removed the largest area of energy waste for human swimmers. The next obstacle is the struggle against excess water resistance (drag). When we minimize drag (by improving body shape and movement patterns) we have removed our second biggest area of energy waste.

Then there is the task of choosing the optimal SPL x Tempo combination to create the desired Pace.

Math - PACE comparison

All four of these combinations produce the same Pace. But which one should you choose to use? That depends on factors I’ve explained in the Metrics 101 and Metrics 102 blog series.

A swimmer using either or both an inappropriate SPL (too long or too short) or Tempo (too fast or too slow) for their body dimensions and event will experience an excess and uncomfortable desperation for more air.

This is what our TI training is for – to learn how to control and adjust both SPL and Tempo, which in turn affects Pace and HR. Switching gears – as on a race car or bicycle – to choose the best balance between fuel consumption and speed.

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