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When you start feeling fatigue in your race (or while ‘just swimming’) you are urged to slow down. At some point you finally must give in. But when you do what is changing in your stroke to slow you down?

SPL x Tempo = Pace (the inverse of the Speed Equation = SL x SR)

When you to slow down from fatigue what changed in this equation for you? What does your brain want to hold on to when the going gets tough? What does it want to let go control of? Are you loyal to holding stroke length and sacrifice tempo? Or do you sacrifice stroke length and hold on to tempo? Or neither? Or “I don’t know!“?

Test Swim

Here is a test you can conduct to check your level of development for pace control. This test swim will challenge your ability to hold Pace (= a certain SPL x Tempo combination) at some point during the test swim.

For this test swim you will need to count strokes on every lap and use a Tempo Trainer to help you hold tempo precisely.

You may pick an SPL N that is within your comfortable conditioned SPL range and a comfortably fast Tempo T you can hold with that SPL, but doubtful whether you can hold it the whole test swim.

For example, Roberto has a conditioned SPL range of 18-20 strokes (in a 25m pool). He is going to assign himself to do this test swim with 19 SPL. And, from experience using a Tempo Trainer he knows he has a comfortable center Tempo of 1.32 (meaning he could hold this tempo all day), and the fast-end boundary of his comfortable tempo range is about 1.25 (which he can just hold for about 200m without feeling like his stroke quality gets out of control). So, Roberto will set his parameters at 19 SPL x 1.25 second tempo.

You may set up a test swim like this, and adjust the distance of each repeat to suit yourself:

4x to 8x 100 meters with 6 nasal breath rest between each. Do as many as you need to in order to start feeling considerable stress on your ability to hold SPL x Tempo together.

Your assignment is to do your best to hold both SPL x Tempo consistently, over every single length of the test swim. But this is not the purpose of the test. You want to find a failure point in your ability to hold that SPL x Tempo combo – that point where you begin to feel it is too difficult to hold both SPL and Tempo at the same time. Then you will observe in your own body which one your brain is more loyal to – holding SPL and give up Tempo (let is slow down), or hold Tempo and give up SPL (add strokes). Making observations at this failure point is the purpose of the test.

The observations to make:

  1. Which did I feel more loyal to under pressure (in the habit sense)- SPL or Tempo?
  2. How did it start to fail? Did I feel like I was losing strength to hold that stroke length? Or did my arms start to feel sluggish and I couldn’t move them through the stroke cycle as fast?
  3. What did my attention do in reaction? What did I try to do to compensate for fatigue? What did I focus on? What commands did I give to certain parts of my body?

Here is an arbitrary grading system:

  • A – maintaining both SPL and Tempo (holding pace)
  • B – maintaining SPL N but allowing Tempo to slip <0.05 seconds (dropping pace less than 1 sec/25m)
  • C – holding Tempo, but allowing SPL to slip to N+1 (dropping pace by over 1 sec/25m)
  • D – holding Tempo, but allowing SPL to slip to >N+1 (dropping pace by more than 2 sec/25m)
  • F – losing control over both SPL (any amount) and Tempo (dropping pace a lot!)

Grade yourself on each repeat. Stop when you get a D or F on a repeat.

Note: You could have allowed SPL to slip to N+1, but increased (speed up) Tempo T – ~0.06 seconds to compensate and maintain pace, but this would have changed two variables at once and then taken you away from the purpose of this test swim. I want to acknowledge that as a legitimate ‘holding-pace’ solution, but one that does not apply to this test scenario. If you can do that already (intentionally) then you need a more challenging test for your skills.


You may notice in this grading system that maintaining SPL is given higher value than maintaining Tempo. It is based on this understanding: that what counts for more in a tough race is your ability to maintain consistent traction on the water (= stroke length), not how fast you can spin your wheels. Tempo is important, but secondary to stroke length. Tempo is a function of stroke length, not a replacement for lack of control over it. Only those who first have control over stroke length can expect to go faster if they increase tempo, even a little bit. Meanwhile, those without control over stroke length take the advice to up the tempo, then find they don’t go faster yet get tired even more quickly. The difference between the two is the ability to preserve stroke length as tempo increases. And to minimize heart rate increase, the swimmer has to hold that stroke length with finesse rather than by adding more power – an uncommon but necessary approach. If you practice tempo increases before you have practiced stroke length control, don’t be surprised when you don’t get faster.

The importance of stroke length control is painfully apparent in this famous (or infamous, depending on who you were rooting for) 2008 Olympic Men’s 400m Relay Race where the French squad was overtaken and blown away by the American squad. After the third leg France had the race in the bag, but inferior stroke control on the part of the final French swimmer, against superior stroke control on the part of the final American swimmer flipped the results. You can see that speeding up tempo did not save the French swimmer – he actually slowed down, while the American was speeding up using a visibly slower tempo. Superior loyalty to (a well chosen) stroke length is the way I would describe the cause of this result.

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Under-developed swimmers (the ones that lose to the best) are chiefly identified by their loss of stroke length toward the end of a race, not by their tempo (whether high, low, or erratic). Tempo only has meaning when it is connected to a steady stroke length. (Take any aqua-aerobics class, have them spin their arms as fast as they can and watch how fast they move through the water as a result!) Adapting to faster tempo is relatively easy to do (with a neurologically effective approach) while developing optimal stroke length – by superior form, rather than by additional power – and then ‘hard-wiring’ it into the muscle memory is much harder to do. The final part of is to combine the two, stroke length and tempo. However, at nearly any pool you may visit the ubiquitous bias of swimmers (and less-than-elite coaches) is to focus so much on (easy-to-learn-and-hold) tempo work, and neglect (hard-to-learn-and-hold) stroke length control work.  Now that I’ve pointed out the irrational bias, you have a chance to work against it to your swimming benefit.

This test above is meant to help you see what you are currently wired to be loyal to: when the going gets tougher than you can handle is your brain hardwired to remain loyal to holding stroke length? Or loyal to holding tempo? Or neither?

A highly developed swimmer will feel energy resources getting strained (like anyone), then double her concentration upon the points in her body position and stroke movements that she knows are most vulnerable to degradation under stress. By this she will delay the speed-reducing effects of fatigue. Then she will make a calculated (and trained for) shift her SPL x Tempo combination to a precise trade-off (for example from ‘N x T’ to ‘N+1 x T-0.06’) to further delay speed-reducing effects of fatigue. The basis of her control over pace is her control over stroke length. Tempo is adjusted in relation to it and her energy supply. If she trained for even splits, she will adjust the combinations (like gears on her tri bike) so that she can maintain pace as muscles fatigue, or as conditions (in open-water, for example) change. If she has trained for negative splits she will start the race with a carefully calculated pace combination so that when she is ready to crank up the speed, she makes her pre-planned (i.e. trained-for) shift – she will either hold stroke length while increasing tempo (more likely), or lengthen stroke and hold tempo steady (harder to do, but possible).

Meanwhile, her under-developed competitors will feel fatigue, lose body position and stroke control, lose stroke length because of it, feel the speed drop, then start cranking up tempo in a futile attempt to compensate, which will deplete energy faster, which triggers more lose of control, which will shorten stroke length further, which will trigger the swimmer to crank up tempo even more. The vicious negative spiral.

This is how we might describe what we saw in Sun Yang’s 2011 World Championships WR 1500m Race (and the subsequent WRs), compared to the swimmers who dropped way, way behind at the end. No one thought he was even close to world-record pace until he unleashed the energy he conserved in the first 14oo meters from an exquisitely maintained SPL x Tempo combination.

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Let’s think about the results of your test swim a bit more.

If you’ve set your starting SPL x Tempo just right you should be able to do the first 1 to 3 of these 100m repeats at Grade A level. But at some point in the series things will start to feel tough. Conditions are changing inside the body. Two main areas to notice: 1) power supply is getting restricted (feeling tired, then feeling exhausted), and 2) attention is getting strained (not knowing what to focus on, not knowing how to counter the exhaustion).

What most swimmers assume has happened is just #1 – “I am just getting tired therefore I can’t swim as fast any more.” The premature and often erroneous assumption is: “Oh, I just need to train harder and build up more power and endurance so I don’t feel tired so quickly.” What ‘I can’t swim as fast anymore’ actually means in physics is: my SPL and/or Tempo collapsed. But I propose that #2 is actually the primary failure, not #1. I argue that this perceived energy- failure point can be postponed a lot longer than a swimmer realizes, if he trains his attention to recognize what is prone to fail in the stroke and train specifically to postpone that failure, and even rise above it.

I suspect that more often than realized, the beginning of the fatigue-inducing problem is that the swimmer has lost attention, and therefore lost control over some part of the body position and stroke control that is vulnerable to degradation, which immediately provokes higher drag, which immediately provokes higher rate of energy loss, which immediately makes the swimmer notice himself slowing down with no ability to resist, which immediately distracts his mind from resuming concentration on those parts of the body position and stroke that started to degrade and cause more drag. Only by breaking the negative cycle at the point of attention loss, can the swimmer regain composure and control over drag increase/energy loss cycle, to delay or even avoid the speed-reducing effects of fatigue.

The fact is, at some point in the test swim (or, in the race) energy supply will diminish, and the swimmer must carry on with a stroke that fits within that lower-energy condition. The question is then: how are you going to compose the stroke with less energy available now? What will you preserve? What will you sacrifice to fit within the budget? Have you ever even thought about this before in this way?

An under-developed swimmer, when less energy is available, will just let the stroke collapse how ever it collapses by default and apply more effort in less productive directions (the land-mammal instincts take over under stress!). However, at the point you can no longer resist the slow-down, you can and should train to sacrifice certain less-valuable-for-speed parts of the stroke cycle in order to conserve energy and fit the stroke within the smaller budget. Regardless of your level of fitness, if you are aiming to race at the peak of your current potential you are going to enter this lower-energy zone during your event. Why not learn to manage your stroke within that zone better and get more out of it?

So, the purpose of this test swim is to get you to practice noticing what is happening in your brain and body so you know what you need to train for. You think, you plan, then you train for it in practice so you don’t have to think about it during the race – this is what it means to build your aquatic mammal instinct. By deliberate practice it will become an easily triggered response (if not totally automatic) and allow you to keep your brain focused on making higher order decisions when your competitors can’t. Being aware of what is happening in your body, then understanding why, is the first step on the path to improving your abilities – in this case, to improving your ability to hold a consistent pace over your entire race distance, even when fatigue sets in. At peak performance you will not avoid fatigue, but you can train to have a superior response to it than your competitors do.


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