Swim Across the Sound (Update 2): Aerobic Threshold Mystery!

Well friends, we have reached the part of the training cycle in which I remember why I retired from competition. Which is to say that I woke up this morning tired and sore to the point that it took a real effort of will to get out of bed and go swim. Looking back on my competitive swimming career these days often feels like remembering that time I had a mental illness. I was mad about everything pretty much all the time, and I used those feelings to fuel my competitive fires. Today I’m in a much better headspace, and that’s great 99% of the time, but boy, it is sooooo much more difficult to find the right mindset when things get tough in training.

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Sally and I went to see Sammy Hagar & the Circle in concert this past Friday night. Fun show, but we wound up drinking a decent amount, and it was hot in there. I won’t say I felt awful Saturday, but I certainly didn’t feel great. Despite drinking a full bottle of water before going to bed Friday night, I still woke up Saturday feeling like a wrung sponge. Managed to put in 4000 yards in the pool Saturday morning while Emma was at dance, but they weren’t, like, great yards. I think the best we can say about them is that they were serviceable.

My main set was three times through:

• 3 x 200 @ 2:50, aerobic pace
• 100 kick
• :30 rest

Aerobic-paced sets can get kind of tricky in the pool. You want to keep your heart rate between 70% and 80% of your heart rate max for an extended period of time. This can be a lot harder to do than you might think. Runners often train to do this using a heart rate monitor -- I’ve done that myself -- but unless you feel like wearing a chest strap when you swim, maintaining a steady heart rate while swimming can be much more challenging. Once you get going, the natural tendency is to speed up, leading to a crash down the line. When you’re training to swim pretty much all day, those kinds of crashes are counterproductive.

So I bought a new swimming watch, the Garmin Swim 2. This thing can take one’s heart rate while swimming, which is amazing.

I have for years assumed that my aerobic heart rate was about 140. Doing aerobic sets, then, I’d typically do 200s with ~10 seconds rest, take my heart rate for 6 seconds between sets, multiply by 10, and there we are. Bottom line, I needed to be around 13-14 beats in 6 seconds to stay on threshold.

Swimming Saturday, my heart rate sat stubbornly between 131 and 136 pretty much all set. The good news is that I swam comfortably at that rate -- if not fast -- but even when I later did a 200 for time at the end of my workout, I could only get my heart rate up to about 146 bpm.

But hey, maybe that was just the hangover talking. Right?

So today I did a shorter workout with longer intervals at a higher intensity. My main set was 2 x (5 x 100 @ 1:30), trying to hold 1:15 or better throughout. This was tempo work, not true speed work, so maybe 85% to 90% effort overall. I took each hundred out steady and tried to build through each rep, and I was between 1:13 and 1:15 all the way through, generally getting faster through each set overall. Performance-wise, this wasn’t too bad. Coming at the end of a long week of training, I was more than happy with it.

Again, though, my heart rate sat stubbornly between 140 and 145 throughout the set with a measured max at 146. Granted, I wasn’t out there doing intervals of butterfly, but still… I’d have expected to get up into the 150s easily. Going by feel, I was definitely hitting 90% effort on the back half of each 100.

Sigh. Maybe my max heart rate has fallen in recent years, I guess because of age. The most recent formula I’ve seen is 211 - (0.64) x age, which predicts a HR Max for me of ~180 bpm. But that still yields an aerobic threshold of around 143 bpm, which is more or less where I’d assumed I’d be going in.

So I don’t know. Either I’m just tired, and that’s making it hard to get legitimately cranked up in the pool -- a distinct possibility -- or else my aerobic threshold is somehow a Hell of a lot lower than it used to be. Or maybe my new watch just isn’t figuring my HR correctly while I’m swimming.

Something is going on.

The article referenced above suggests a methodology for finding one’s max heart rate that would involve something like 3 x (2 x 50 Fly @ 1:00) tempo pace. I might try that next week just to see if I can get up into the 170s. Certainly, that’s about where I’d expect to be on a set like that.