Training for marathon swims: Pool vs. open water

Newbie marathon swimmers often wonder how they should allocate their training time between the pool and open water. There’s no simple answer: It depends on a variety of factors unique to the individual. A few questions to ask yourself:

What’s the target swim? Distance, water temp, conditions, etc. The further outside neutral conditions your target swim is, the more open water you’ll want to incorporate into your training. (To train for cold water… swim in cold water.)

Are you training to finish (regardless of time), or are you training to race? The more speed matters in your target swim, the more high-quality interval training in the pool you’ll probably want to do.

What’s most convenient? If you live next to a safe body of open water, but far away from the nearest pool, this may tip the balance towards OWS. In my experience, convenience promotes consistency — and consistency promotes results.

What do you inherently enjoy? If you have access to a high-quality Masters pool squad with good coaching and fun lanemates, this may tip the balance towards the pool. If you get blissed out by open water, this may tip the balance towards OWS. Enjoyment promotes consistency, and consistency promotes results.

Consistency is the main thing, and I’d say whatever formula helps you swim consistently is fine.

For the sake of argument, though, let’s say convenience and enjoyment don’t pose obstacles for you. All else being equal, what’s the ideal combination of pool & open water training?

My personal beliefs are, you can’t beat the pool for improving speed and stroke technique; and you can’t beat open water for acclimating to cold water and rough conditions.

Perhaps that’s just common sense. But there are some less-obvious corollaries:

In my opinion, for many mainstream marathon swims it’s perfectly OK to do most of your training in the pool. When I did the 24-mile Tampa Bay Marathon Swim in April 2011, I hadn’t been in open water since the previous October.  I won by 42 minutes.

I don’t mean to say open-water training isn’t valuable or important; but I do think sometimes marathon swimmers underestimate the value of pool training.

In that vein, I was struck by this recent tweet from Swim Smooth founder and 2013 MIMS champion Paul Newsome:

Like me, Paul comes from a pool-swimming background, but as an adult competes primarily in long-distance open water swims. Like me, he does most of his training in the pool, even for moderately “cold” swims such as MIMS 2013 (61F).

Among elite professional open water swimmers, the ratio of pool to open-water training approaches 100%. In the case of my old friend Mark, who competed in the Beijing Olympic 10K, his pool training didn’t “approach” 100% – it was 100%. Aside from organized races, he did literally zero open water training in preparation for the Olympics.

What are the exceptions to this rule? You probably already know the answer: very long, very cold swims. You must acclimate. The colder and longer the swim, the more longcold water training you should be doing. For me, anything below about 18C (64.4F) for marathon distance, and I’d aim to be doing at least some of my training outside the warm pool, in cold water. At 15C for the target swim, I’d spend proportionally more time in open water. At 12C, even more. Body fat will also be a factor here.

But still, even for long, cold swims — I probably wouldn’t let my ratio of pool-to-OW training go below 50%. The pool is just so, so much better for developing (and maintaining) speed and fitness. The extra speed (resulting in faster times) and extra fitness (resulting in the ability to maintain higher energy output for longer), more than make up for the opportunity costs in cold-water acclimation.

Taking liberty with a well-known proverb:

All OWS and no pool makes Jack a slow swimmer-boy.

A chlorinated swim

Last weekend I drove 90 minutes for a 19-minute swim – which would be unusual for me nowadays, even for an open-water swim. But this was a pool swim! Heresy!

There were other good reasons for the trip, however. I met up with my old buddy Rob D., as well as fellow SBCSA director Dave VM. Dave joined me for 30 lengths of freestyle, while Rob lap counted and shot some video with his GoPro. Later, we caught up on the latest OW/marathon swimming gossip over beer and burritos. Good times.

San Luis Obispo Swim Club occasionally puts on combined USA-S/USMS meets, and this was one such occasion. I had no interest in hanging out on a pool deck all day dodging 10-year olds… but they were offering a 1500 (LCM) as the last event of the day, and it was tempting. I could sleep in, show up early afternoon… get in, get out…. one and done.

When I showed up, the kids’ meet was still in full swing and they were running only a single warm-up lane. Which led to scenes like this:

Photo by Rob D.

Soon enough the non-1500 portion of the meet concluded and most of the kids cleared out. There were four heats of age-group milers, followed by a final Masters heat with me and Dave VM.

It would be my first long-course 1500 since… wait for it… August 1997. Almost 15 years ago! As a Masters swimmer I’ve done the SCY 1650 (twice) and the SCM 1500 (once), but not the LCM version. So I was interested to see what I could do (albeit unshaved, untapered, etc.)

Rob brought his GoPro to film the proceedings. He attached it to the lap counter, resulting in some cool underwater & turn footage.

Evan’s 1500m at SLO LCM from Rob Dumouchel on Vimeo.

My time: 18:56.72. Average pace per 100m of 1:15.8. This was… okay. I wanted to be under 19, and I was (barely). My splits were reasonable:

1:12.2, 1:14.9, 1:15.3, 1:15.8, 1:16.0 = 6:14.1
1:16.3, 1:16.4, 1:16.3, 1:16.1, 1:16.3 = 6:21.4
1:16.0, 1:16.2, 1:16.9, 1:16.8, 1:15.3 = 6:21.2

For shits & giggles, I plotted these 100 splits against two other swims from earlier in my life.  The blue line shows last weekend’s swim. The red line shows my first-ever 1500, just after I aged up as a 13-year old. The green line shows my last-ever 1500, as a 17-year old.

I won’t be offering any heavy interpretation here, but what I’ll say is: This is why I do open water.

In praise of the pool

Pools sometimes get a bad rap among open water swimmers. Marathon swimmers who live outside the Sun Belt are known to bemoan long winter hours in the “concrete prison.” David Barra memorably quipped to the New York Times:

The free spirits want to be outdoors, and have a relationship with a body of water…. You don’t have a relationship with a chlorine box.

Hearst Castle. San Simeon, CA.

But pools have their uses – even for marathon swimmers. Especially if one of your goals is to get faster. Alex Kostich was a U.S. National Teamer, an All-American distance swimmer at Stanford, and a training partner of Janet Evans in her prime. Now 41, Kostich is possibly the fastest Masters open-water swimmer in the country at the short distances (up to 5K). In the July/August issue of USMS Swimmer, here’s what he had to say about pools:


The easiest and most efficient way to get faster in open water is to do quality work in the pool.

Kostich is an open water specialist. He lives in Los Angeles. Yet he doesn’t train in open water.

He isn’t unique in this regard. Friend-of-the-blog Mark Warkentin, who also lives on the California coast, did nearly 100% of his training for the 2008 Olympic 10K in pools. Take a poll of the current open-water National Teamers, and you’re likely to find that all of them do the vast majority of their training in pools.

Pools are useful because they make training quantifiable, measurable, and precise. In pools there is accountability and objectivity. Ironically, many of the factors that make open water enjoyable – its freedom and unpredictability – are the same ones that make it less than ideal as a training environment.

The two best ways to get faster are to (1) improve your technique, and (2) improve your cardiovascular conditioning. In the pool, it’s easier to monitor and adjust technique. In the pool, it’s also easier to do the “quality” work necessary to improve your conditioning. That said, training in open water is useful, I believe, in three regards:

  1. Cold water acclimation. There simply is no substitute (including ice baths). If you want to swim in cold water, swim in cold water.
  2. Rough water acclimation. This is an area where I’ve really improved since I moved to Chicago last year. My success in the choppy first few miles of Tampa and the choppy last 10 miles of MIMS was probably due, in part, to my training in Lake Michigan (which is, more often the not, choppy).
  3. Over-distance training. For the long (10K+) swims that are an essential (if only occasional) element in the marathon swimmer’s training regimen, I find open water preferable to the pool. It’s easier, psychologically – time passes more quickly in open water. That said, I still think my 25K pool workout in March better prepared me mentally for Tampa and MIMS than anything else I did.

See, the chlorine box isn’t so bad! Especially if the chlorine box looks like this:

Los Baños del Mar Pool. Santa Barbara, California.

Short Course: The bad news

I recently noted an unforeseen benefit of doing long swims in a short-course pool: It’s easy to monitor your stroke count without counting!

That’s the good news.

The bad news?

Swimming for a long time without stopping in a short-course pool can increase the risk of tossing your cookies.

I assume this has something to do with flip turns, and I also assume it depends on what you’ve eaten recently. I didn’t have a problem in the One Hour Postal last year, but I occasionally do get nauseated during these swims.

It goes with the territory. Just ask Dave Barra, who did a memorably gruesome 30,000 SCY workout at about this same time last year.

The joys of short course

As I alluded to a couple weeks ago, I won’t have access to long-course water until mid-April. And Lake Michigan won’t be swimmable until probably late May (maybe a bit earlier with a wetsuit). Which means my ramp-up into Tampa will take place exclusively in short-course pools. Yuck.

At least once a week (see last Wednesday’s workout, for example), I try to do some long, aerobic steady-state swimming. 15 or 20 minutes at a time, to mimic my feeding schedule – or, as I build up, a series of such swims.

In doing these long swims, I’ve observed a couple things about short course that, in all my years of swimming, I had never noticed. There’s good news and bad. We’ll start with the good:

In a short-course pool, it’s much easier to monitor stroke count, and therefore swimming efficiency. The reason is, at any given pace my stroke count generally has a range of only 1. (N.B. I define “strokes” as the number of hand entries, counting both arms.)

For me, at a typical workout pace (say, 75% effort) my stroke count is usually 14. If I’m having a good day in the water, it might be 13. If I’m thrashing, it might be 15. But within a given swim, I’ll generally be in either a “13/14 mode” or a “14/15 mode,” depending on how I’m feeling. If I’m focusing on stroke count specifically, it’s not too difficult to hit 14 strokes every time.

The key is, when your stroke count range is only 1, you can actually monitor your stroke count without counting! All you need to know is which arm hits the water right before the turn. Since I always begin each lap with a left-arm stroke, if I end a lap with a right-arm stroke, that means 14 strokes. If I get tired and lose some efficiency, I get immediate feedback because after my 14th stroke I’m not quite there and am forced to take an extra one – with my left arm.

The point is – this is only possible in a short-course pool. In a long-course pool, my stroke counts are in the mid-30’s and subject to wider ranges. Long-course pools are appreciated by distance swimmers for the relative ease of getting into a good “rhythm,” because there aren’t as many walls to interrupt you.

The lesson here is that in some ways, short-course pools facilitate “rhythm” because they give you such regular, insistent feedback about your efficiency (“14, 14, 14, whoops there’s a 15, what did I do wrong?”).

Next up: the bad news.