Adventures in exercise physiology: Tampa edition

Best I can tell, I lost about 1 pound of body mass during the Tampa Bay Marathon Swim. Actually – probably closer to 1.5 pounds, but we’ll call it a pound. Marathon swimmers often lose substantial weight over the course of a swim, but most of this is water loss that is soon regained. I estimate that I lost a little over a pound of body mass – that is, fat (and possibly some protein cannibalized from my muscles). For convenience, we’ll call it a pound of fat.

Some back-of-the-envelope calculations:

Losing a pound of fat requires an energy deficit of 3,500 calories. I consumed 2,800 calories during the swim. That puts my total energy expended during the 9-hour swim at 6,300 calories — 700 calories per hour.

This tells me a couple of things. First, my energy expenditure is higher than I expected. 700 cal/hr is the typical estimate for “vigorous” swimming – but this was my ultra-marathon pace. Second, I can probably experiment with raising my calorie consumption. I took 311 cal/hr in Tampa, but when I’m burning 700 cal/hr that puts me in deficit within, at most, 5.1 hours (assuming 2,000 calories pre-stored glycogen), and possibly as little as 3.8 hours (assuming 1,500 calories glycogen).

Jared, am I thinking about this the right way?

Race Report: Tampa Bay Marathon Swim

Part 1: The Team

Without a team, a 24-mile swim doesn’t happen. Simple as that. And the swim’s success – it’s efficiency – depends on the quality of the team. Long swims are isolating experiences: A swimmer and his thoughts. But there’s an irony: The longer the swim, the more you utterly depend on your support team.

So any discussion of my experience in Tampa Bay must begin with my team.

The Team (L-R): Kathy, Carl, Pat, Michael, Kim… Frankland Bridge in the distance. (Photo Credit: Distance Matters)

It’s tough to overstate how fortunate I was. Continue reading “Race Report: Tampa Bay Marathon Swim”

On “ultra”

NOTE: I wrote this as preface to my Tampa report, but it got a bit long so I decided to put it in a separate post. It’s not really specific to Tampa, anyway.

What’s a marathon swim? Without any historical reference point (as for marathon runs), there are various definitions. The official FINA and (as of 2008) Olympic distance is 10K – which has the virtue of similar finish times as marathon runs. Penny Lee Dean sets the bar at 16 miles. Ted Erikson says 10 miles. Steven Munatones, as usual, wrote a nice overview of the issue.

I’m not really interested in debating what is or isn’t a marathon swim, though I do think:

  • It must be in open water.
  • It should be nearly impossible (or at least very difficult) to finish without refueling mid-swim.
  • It should be very difficult to accomplish without support.

So, I’m fine with calling 10K a “marathon swim.” What about 24 miles, though? Typically, that’s described as an “ultra marathon swim.” My reason for discussing semantics here is, there’s something about a swim of that distance that’s not captured by merely adding the word “ultra.” A 24-mile swim is qualitatively (not just quantitatively) different than a 10K.

It’s different physiologically. In a 2-2.5 hour 10K, you’re still within the range of your pre-race glycogen stores (perhaps topped off with a couple mid-race feedings). Which means it’s possible to swim at near-threshold pace for the entire swim. In a 24-mile swim, you burn through not only your entire cache of muscle glycogen (perhaps 1,500 calories), but you’re burning through more calories per hour than you can possibly consume. Which means you must start metabolizing fat – a plentiful but less rapidly mobilized energy source – and swim at a substantially slower pace.

Even more important, a 24-mile swim is different psychologically. I’m thinking of two big issues here. First, failure is a distinct possibility, even for the best swimmers. Seasickness, digestive problems, hypothermia, tide changes — all can potentially end a swim. DNF’s happen in 10K’s, but as long as you’re a reasonably good swimmer and the water isn’t below about 16C, they’re pretty rare. In a 24-mile swim, you’re truly at the mercy of the swimming gods, no matter who you are.

My training partner Jared wrote a great piece on this issue from the perspective of a triathlete.

Second, a swim this long is almost inevitably a struggle. There will be dark phases, and you can’t avoid them. You’re standing on the beach before the start, staring out at the water, and you know what’s coming. Maybe not the specifics of it… but you know there will be pain and doubt and frustration and possibly thoughts of giving up — but that you must try to push through them — to endure. This simply isn’t comparable to a 4-5 loop 10K (not to mention any pool race).

In any case, Tampa was my first ultra-marathon swim. I’ve never attempted anything like it; not even close. And the word “ultra” doesn’t quite communicate what a quantum leap it was.

Tampa, in brief

I thought I should get something out now (however brief), with a more comprehensive report to follow. Yesterday was an experience that… will take a couple of days to process.

I fulfilled my goal of finishing the Tampa Bay Marathon Swim. The time (8:59) and place (1) were nice, but finishing was the hard part.

A few stats (some actual, some approximate):

  • water temp: 80F
  • air temp: 70F (low) to 88F (high)
  • wind speed: 15 mph (morning) to calm-ish (afternoon)
  • calories consumed: 2,800
  • calories burned: 5,000+
  • fluids consumed: 320 oz (9.5 liters)
  • strokes taken: 33,500 (a few on my back, for various reasons)
  • pace per mile: 22:27

Here are the data from the GPS transponder on my escort boat (ignore the blue line):

Credit my boat pilot for that incredibly true line. More on him later.

If you’re wondering about the detours at the bridges, that’s because certain portions of those bridges are too low for the boat to pass under. Specifically, the parts crossing over the shortest path to the finish. So the boat went around to find higher clearance, while my kayaker and I went under.

A few good links:

A nice moment:

Don’t underestimate Tampa

Some people do the Tampa Bay Marathon Swim as a “warm-up” for one of the triple crown swims. And it makes sense: Tampa is early in the season, 8 weeks before MIMS and more than 3 months before high season for channel crossings.

But thinking of Tampa as a “warm-up” might tempt a person to take it less seriously – and that would be a big mistake. TBMS is one of only four annual organized ultra-marathon (25K or longer) swim races in the U.S. (along with MIMS, Ederle, and Swim Across the Sound), and it may be the toughest. While water temperature is not usually a factor, pretty much everything else is. Glancing through the archives, tide changes and rough seas seem to be the two big ones.

Swimmers typically start with the flood tide, which pushes them up Tampa Bay — for a while. If you don’t swim far enough over the next few hours, though, the tide reverses direction and starts to push you back towards St. Petersburg – making it effectively impossible to finish.

Tampa Bay is also quite large, so conditions can mimic those in the open ocean. Here’s what the Bay looked like in four recent years (click to enlarge photos):

2010 – 4/7 finished
2009 – 7/11 finished
2008 – 6/8 finished
2005 – 7/19 finished

Since Ron Collins’ pioneering swim in 1998 (9 hours, 52 minutes), there have been 149 solo entrants in the annual race. Of those 149 swims, 70 were DNF’s – they didn’t finish the full 24 miles. That’s a success rate of 53%. By comparison, over the same time period, 90% of MIMS entrants have successfully rounded Manhattan (239 of 266, not including those who withdrew before the event).

There are other factors at work, of course. The MIMS selection process likely “weeds out” swimmers least likely to finish, based on swim speed or previous cold water marathon experience. I don’t believe Collins has yet rejected anyone from attempting TBMS – which is a good thing, in my opinion.

But Tampa Bay has humbled some great swimmers. In one recent edition, a swimmer who is perhaps the best non-professional marathon swimmer in the U.S. retired due to seasickness. Last year, a well known swimming guru (who had twice finished MIMS) planned to swim TBMS, Catalina, and the English Channel, all in the same year. After Tampa (which to his credit, he finished), he decided: maybe I’m not a marathon swimmer, after all. In 2007, tragically, one swimmer passed away from a heart attack.

The point is, this swim is a beast. I’m preparing for it as such.

Pre-Tampa training swim

Last weekend I did a rather epic pool workout (as you know if you follow my Twitter feed). An unexpected excuse came up for a quick trip to Santa Barbara, and given my current lack of long course or open water options in Chicago, I decided to use the opportunity for a pre-Tampa training swim. The Rec Center at UCSB has a beautiful outdoor 50m x 25y pool that – conveniently – is open for LCM lap swimming from 9am to 8:30pm on the weekends.

Despite a chilly morning, it turned into a gorgeous day. With cloudless skies, a light breeze, and mid-day highs in the 60s, I actually worried about getting sunburned. When the front door opened at 9am I went straight to the pool to claim my lane – second from the bottom of the picture, with the best viewing angle to the pace clock. Incredibly, nobody joined me in that lane until the last 15 minutes of the swim.

In designing the workout, I aimed for something that would challenge me in terms of distance, time, and pace, but without boring me to death. So I ruled out a long continuous swim, or something overly repetitive like 15×1000. I aimed for something I could realistically do, but that also offered a not-insignificant chance of failure. My previous longest swim/workout in terms of both time and distance (including my club and college swimming days) was Swim the Suck last October – 10 miles (effectively ~8.5 given the favorable current) in 3 hours, 7 minutes.

I eventually settled on a 25,000-meter (15.5-mile) set that, at a constant interval of 1:30 per 100m, would take 6 hours, 15 minutes. This would approximately double the Tennessee River swim and put me within spitting distance of the current-assisted length of TBMS. While a 1:30/100m is a conservative interval for me under most circumstances, at marathon distance I knew it would pose a challenge. As a point of reference, a 1:30 pace for 10K is 2 hours, 30 minutes – no slouch of a time. It’s also interesting to note that only 4 of 45 competitors in the last USMS 25K National Championship finished under 6:15.

And remember, a 1:30 interval means my actual pace must be faster than 1:30, so I have time to feed between swims.

Anyway, here’s the set:

  • 1000
  • 10×100
  • 1000
  • 5×200
  • 1500
  • 5×300
  • 1500
  • 3×500
  • 2000
  • 4×500
  • 2000
  • 5×400
  • 1500
  • 5×300
  • 1000
  • 5×200
  • 1000
  • 10×100

I maintained my normal training volume going into the swim, though I did take off the day before. My energy level and general “feel for the water” during warm-up rated about a 6 on a scale of 1-10 – not ideal, but good enough.

After a quick 500m loosen-up, I did the first 1000m swim in 14:05 (pace of 1:24.5) – right on target. I managed to hold this pace for the first 10K (3×500). On the first 2000m swim (10-12K) I started hurting a bit and my pace deteriorated slightly; but I was still getting plenty of rest between swims. The second 2000m (14-16K) was slower still, and hurt even more.

By the “downhill” portion of the set (1500, 5×300, 1000, 5×200, etc.) I was fully ensconced in the hurt box. I experienced what I can only describe as a “narrowing” of consciousness. I had no idea what was going on around me; my stroke was on autopilot; I was aware of only the pain. But I kept making my intervals. Not by much – especially on the shorter swims – but I made them.

I finally did cross over the 1:30/100m barrier on the final round of 10×100. I started feeling dizzy and thought I might puke, so I just swam a straight 1000, alternating 50 back / 50 free. In the end I finished the 25,000th meter (excluding warm-up) a few seconds shy of 6 hours, 16 minutes.

Then I pulled myself out of the pool, chugged a quart of chocolate milk, and took a hot shower. I had entered the water a few minutes after 9am. It was now almost 3:30 in the afternoon.

That evening I watched the Oscars with my parents. I felt like I’d been run over by a truck, but I washed down some ibuprofen with a few glasses of wine (probably not the healthiest combination), which numbed me up pretty good. The next day my shoulders were still a bit perturbed, but I was better. Two days after that: as good as new.

25K training swim: check.