IM Swim Split - How Fast Do You Need To Be?

Triathlon Forum
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Not intended as the conclusive mathematical guideline, but perhaps a way to start looking at the question? How does your experience compare?

How Fast Do You Need To Be?
Masters athletes, and new to swim athletes in specific, often think about what kind of paces they can hold in training in terms of sets of 100s, sets of 200s, etc, with the goal to improve their time for swims that are greater than or equal to a mile in length. When seeking greater speeds in those sets they tend to ask what technical improvements they can make, and seek to make those improvements in the course of their workouts doing 100s, 200s, etc. while thinking about their stroke.

But as you practice some new technique, your body is inevitably weak in terms of repeating that technique because it has not practiced it much. The technique will therefore tend to degrade as one swims 25, 50, 75+ yards continuously. In my experience, this degradation is so pronounced that much of the technique change that is desired disappears after roughly 50 yards, and the stroke becomes unrecognizable after 100.

If we accept this as a truism for many athletes, shouldnt we instead try to focus on how fast they can swim 25 yards at a pop? And to make us focus on how fast we can do 25 yards, and how many 25 yard repeats we can do? For some context, I wanted to look at just how fast one needs to be in an all out 25 in order to reach a given speed in a mile. The two current American record holders in the 1,650 yard freestyle are as follows:
Womens 1650 record holder Katie Ledecky, 15:03, averaging 54.7 / 100, or 13.7 seconds per 25.Mens 1650 record holder Clark Smith, 14:22, averaging 52.3 / 100, or 13.1 seconds per 25.
Lets estimate that Katie Ledecky can swim a 25 in 11.0 seconds. Estimate that Smith can go a 10.0 for his 25 sprint. If we take these as reasonable estimates of their top speed capabilities (if someone has exact knowledge, feel free to share), then for their record swims, they averaged approximately 3 seconds per 25 slower than their all out speed. 3 seconds per 25 at these speeds means that their endurance time per 25 is about 130% of their sprint lap time. Lets say they can average an additional 1 second per 25 slower for a 2+ mile swim, which would equate to a lap time of ~ 140% of their all out sprint.

So if you are physiologically suited for the a 15-20 minute event, and trained to the limit of your endurance capabilities, then you should be able to average approximately 130% per 25 of your all out 25 sprint time, and you can do 140% per 25 in a multi-mile swim. What does this mean in terms of performance in an open water endurance race?

So if you can swim an all out 25 yards in 14 seconds, your 2.4 mile swim pace should be in the ballpark of 14 x 140% = 19.6 / 25 or 1:18.4 / 100 or a low 55:00 swim split

If you can swim an all out 25 yards in 15 seconds, your 2.4 mile swim pace should be in the ballpark of 15 x 140% = :21 / 25 or 1:25 / 100 or a low 59:00 IM swim split

If you can swim an all out 25 yards in 18 seconds, your 2.4 mile swim pace should be in the ballpark of 18 x 140% = :25.2 / 25 or 1:41 / 100 or a roughly a 1:11 IM swim split.

A formula to start with is SP x 1.4 x 4 x 42.2 / 60 = IM swim (Split where SP = 25 yard sprint pace in seconds from a push)

Even simpler would be IM swim split in minutes = 3.9366X (where X is your 25 yard sprint time)

From Robert Burgholzer, FF Founding Coach, via Athletic Algorithms on Wordpress

Correct Math courtesy of Eric Mulk

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Who’s Grodzki?

I’m not quite sure what you’re recommending here. I doubt you are actually recommending a diet of strictly 25s, but that seems to be the gist of the words that are written there. .

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Grodzki was the US Open record holder when this was originally written. Thanks for the heads up, I edited him out.

I’m not recommending strictly 25s. It’s just a quick blog. A suggestion for an approach to look at the pool to open water correlation. 25s and 50s have their place, as do longer swims. “A*s you practice new technique” *is where I propose that distinction is implied.

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Grodzki was the US Open record holder when this was originally written. Thanks for the heads up, I edited him out.

I’m not recommending strictly 25s. It’s just a quick blog. A suggestion for an approach to look at the pool to open water correlation. 25s and 50s have their place, a do longer swims. “A*s you practice new technique” *is where I propose that distinction is implied.

Interesting…and I thought this was something written orginally by RWB as it would appear here.

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Grodzki was the US Open record holder when this was originally written. Thanks for the heads up, I edited him out.

I’m not recommending strictly 25s. It’s just a quick blog. A suggestion for an approach to look at the pool to open water correlation. 25s and 50s have their place, a do longer swims. “A*s you practice new technique” *is where I propose that distinction is implied.

Interesting…and I thought this was something written orginally by RWB as it would appear here.

ummmm.

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i can not come close to swimming the times in your post, but im pretty close to a70 minute swimmer in an IM and that is good enough for me to podium/KQ in a tough age group because i go a lot faster on the bike and run.

the point being for me is comparing to ledecky and other great swimmers is not all that relevant and just makes me feel i suck. each triathlete had different strengths and abilities. for you, the posted data and analysis may be relevant. for me, i can’t swim the times you mention for 50 yards let alone 4200.

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Why 25’s though? Honestly curious.

While I’m sure it can be done, repeat 100s, 150s, 200s are a much better gauge as I’m sure you know. My personal favorite… 11x150s

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Grodzki was the US Open record holder when this was originally written. Thanks for the heads up, I edited him out.

I’m not recommending strictly 25s. It’s just a quick blog. A suggestion for an approach to look at the pool to open water correlation. 25s and 50s have their place, a do longer swims. “A*s you practice new technique” *is where I propose that distinction is implied.

Interesting…and I thought this was something written orginally by RWB as it would appear here.

Correct. https://www.patreon.com/posts/15510757

Rob is my good friend and my founding partner in Finding Freestyle, but doesn’t want to participate here. It was shared with permission and credited elsewhere. I edited the OP as yeah, I should have done that originally. His original had some dead links and outdated times.

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Why 25’s though? Honestly curious.

While I’m sure it can be done, repeat 100s, 150s, 200s are a much better gauge as I’m sure you know. My personal favorite… 11x150s

25s are a good place to start. If you cant’t do it for a 25,… That’s all. Like a mile time being a good predictor of marathon potential.

From the blog “as you practice new technique”…25s and 50s are a good place to do that.

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i can not come close to swimming the times in your post, but im pretty close to a70 minute swimmer in an IM and that is good enough for me to podium/KQ in a tough age group because i go a lot faster on the bike and run.

the point being for me is comparing to ledecky and other great swimmers is not all that relevant and just makes me feel i suck. each triathlete had different strengths and abilities. for you, the posted data and analysis may be relevant. for me, i can’t swim the times you mention for 50 yards let alone 4200.

Do you ever time yourself for an all out 25’? Are your 70 minute swims wetsuit or non wetsuit?

The point wasn’t to compare you to much faster swimmers, it was to gently suggest that your rate of speed decay from short to longer swims might be similar to faster swimmers.

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I would guess that Smith is about 19 flat or so for a 50 from the blocks. So a flat out 25 from a push would be right around that 10 to 10.5 mark.

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I would guess that Smith is about 19 flat or so for a 50 from the blocks. So a flat out 25 from a push would be right around that 10 to 10.5 mark.

Yeah, basically what was suggested right? Though 10.5 is significantly different in terms of percent of speed degradation.

The point of the post wasn’t to suggest doing 25s exclusively until you can get to 17 or 18 or whatever, rather as a data driven approach to examine this pretty common question (from the perspective of the shortest available pool repeat).

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Why I think you’re very right, and this post is useful, is that overall speed potential is a pretty good proxy for swim mechanics. Most triathletes are too used to thinking about sub-maximal durations as the key to predicting bike and run times, but swimming technique is such a big limiter that 25s are in some ways a better indicator.
Also, in training, changes at the 25 distance can be a great indicator of potential that can’t yet be realized in a 200 all out, let alone 3.8.

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I would guess that Smith is about 19 flat or so for a 50 from the blocks. So a flat out 25 from a push would be right around that 10 to 10.5 mark.

Yeah, basically what was suggested right? Though 10.5 is significantly different in terms of percent of speed degradation.

The point of the post wasn’t to suggest doing 25s exclusively until you can get to 17 or 18 or whatever, rather as a data driven approach to examine this pretty common question (from the perspective of the shortest available pool repeat).

Know anyone at UTexas? The only place that I think he “might” have done a timed, flat out 50 would be at their practice meet “the Eddie Reese Invitational” that the SwimSwam guys have covered a few times, but they never showed Clark’s times.

Thinking about it, 19 flat might be optimistic for Smith. A guy like Joe Schooling is 18mid, and a MUCH better sprinter than Smith. I’m changing my mind to 19 high…

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Like many sports, you need various elements of your swim technique to become second nature, because really you can only improve one element at a time, whilst the others work away in the background to a greater or lesser effect. For me I find my catch & pull is what I need to go back and focus on now, because as I fatigue my ‘feel’ for the water reduces and I need to delay this issue - and concentrate more on feel as my sets go on. In the background my leg position, hip rotation & head position are all happening automatically.

So in my 40*50m today, I wanted to make sure I got a big arm-full of water I could really feel for all 40 of those reps. If the water doesn’t feel like syrup, then I’m not doing it right. Thoughts?

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Like many sports, you need various elements of your swim technique to become second nature, because really you can only improve one element at a time, whilst the others work away in the background to a greater or lesser effect. For me I find my catch & pull is what I need to go back and focus on now, because as I fatigue my ‘feel’ for the water reduces and I need to delay this issue - and concentrate more on feel as my sets go on. In the background my leg position, hip rotation & head position are all happening automatically.

So in my 40*50m today, I wanted to make sure I got a big arm-full of water I could really feel for all 40 of those reps. If the water doesn’t feel like syrup, then I’m not doing it right. Thoughts?

With limited information, best I can say is I have no arguments with your approach to that 40x50 set (Great set BTW!) The sensation of producing high force is certainly something that needs to be focused on along the way towards developing your optimal stroke.

If you have not already, I would consider how the timing of the kick to the pull contributes to effective propulsion. I am serving up a 4 week module in an attempt to teach this. Part one was posted this past Sunday, and part two I am working on now to post t his Sunday.

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Hmm… More like if you can’t do it for 25 you probably have no chance to do it for 2.4mi but if you can it doesn’t mean you will. We recently did a mini swim meet wit our masters group. Here are some interesting times:

50 free:
Me: 27.59
John: 27.44

100 free:
Me: 58.69
John: 1:02.18

500 free:
Me: 5:53.83
John: 7:20.72

My IM swim PR is 56 with wetsuit, John swam a 2.4 OWS in 1:37 (non wetsuit)

Why 25’s though? Honestly curious.

While I’m sure it can be done, repeat 100s, 150s, 200s are a much better gauge as I’m sure you know. My personal favorite… 11x150s

25s are a good place to start. If you cant’t do it for a 25,… That’s all. Like a mile time being a good predictor of marathon potential.

From the blog “as you practice new technique”…25s and 50s are a good place to do that.

18

Hmm… More like if you can’t do it for 25 you probably have no chance to do it for 2.4mi but if you can it doesn’t mean you will. We recently did a mini swim meet wit our masters group. Here are some interesting times:

50 free:
Me: 27.59
John: 27.44

100 free:
Me: 58.69
John: 1:02.18

500 free:
Me: 5:53.83
John: 7:20.72

My IM swim PR is 56 with wetsuit, John swam a 2.4 OWS in 1:37 (non wetsuit)

So you could maybe hold 1:10 - 1:12 for a set of 100 repeats at threshold intensity? (Maybe10 x 100 on the 1:25?) Which is a little under the 1:13 postulated to deliver a one hour swim?

And John’s fruit isn’t just low hanging, it’s probably on the ground rotting.

19

There is no one answer to that question, but if you look at the whole of an Ironman as an energy management challenge, then you, want to stay reasonably close to your competition, using the the least amount of energy as possible, so that you can then maximize your bike/run performance!

Generally speaking most modern triathletes don’t swim enough in training nore take the time read-years, if new to swimming to really build up a BIG swimming fitness base. Thus, the swim is taking WAY too much out of them right at the start if the race, and the race has really just begun.

I’ve stood at water’s edge, and watched a whole IM race field come out of the water - it’s clear that many are almost completely overwhelmed by the swim. This does not set them up for a good day!

20

There is no one answer to that question, but if you look at the whole of an Ironman as an energy management challenge, then you, want to stay reasonably close to your competition, using the the least amount of energy as possible, so that you can then maximize your bike/run performance!

Generally speaking most modern triathletes don’t swim enough in training nore take the time read-years, if new to swimming to really build up a BIG swimming fitness base. Thus, the swim is taking WAY too much out of them right at the start if the race, and the race has really just begun.

I’ve stood at water’s edge, and watched a whole IM race field come out of the water - it’s clear that many are almost completely overwhelmed by the swim. This does not set them up for a good day!

No lies spoken there Steve.

Maybe the best we can do is get people swimming more, and develop a simple range… say perhaps your 2.4 mile swim split should see 25 yards splits between 125 - 145% of your all out 25 yard swim time? If you are over that (or on the upper end), an examination of why your speed is degrading too much is in order. Lack of fitness or insufficient repetition of proper mechanics within shorter repeats? Or both, or something else? Navigation? Open water comfort? The point being there can be a data driven approach.