Depending on how much rest, that *could* be a reasonable proxy. Did you start on pace and die, or hold an even pace that was a second per hundred slower?
I think some longer intervals are also really useful, even if they wind up being slower than mile pace. A favorite set of mine is 10x300. This complements rather than replacing the 100s.

Leading up to the race, I was able to do 25 X 100 at < 1:14 on a 1:35 interval. I once was even able to do 20 of them on a 1:30 interval. Was hoping, when adding time for a 4th flip turn, that would translate to a sustainable 1:15/100 pace for the 1650. Wasn't really the case. I was already over 1:15/100 by the 300y mark. Went 1:16.50 on the 5th 100, and kept in the 1:16.5-1:16.9 range though the 1000 mark. I was a little more ragged on the third 500, with 100 splits between 1:16.5 and 1:17.9 . Went 1:16.4 on the 16th hundred, and closed with a final 50 of :35.20.

Long story short, it wasn't the optimal race execution, but it was far from a "go out fast and die" train wreck. The guy in the lane next to me was a good example of that; he was 6 seconds ahead of me at the 500 mark, but I caught him by ~900, and finished 21 seconds ahead of him.

Were you in a tech suit? I'd say it's much more likely to be a good proxy with that boost. That's probably another way of saying that yeah, you're likely to be a second or two slower.
It's also important to say: practicing that race and being *well rested* is a big deal, especially in the 1650. If it was toward the end of your day, or you were tired going in, you're definitely not going to be able to hit your optimal times.

7.1 mi run 65:02
675 yd swim

7.1 mi run 65:02
675 yd swim
OK OK....I'm going to beat on this thread again. Is this thread supposed to be about bragging rights about workouts and feats of strength, or are we going to actually learn about swimming from each other. Posting workouts without talking about what the whole point of the workout was all about seems to make the thread less interactive. Sorry for beating on you, but there is a training log to just enter workouts....can we have some discussion.

Dr. Tigerchik wrote:

I swam 650 yards of freestyle then kicked 25 to cool down :-)

The reasoning behind my workout of 4500y:

1) mostly aerobic or higher-end aerobic, since yesterday was a short sprint workout.
2) aerobic because I wanted to work on something that I should have been applying for a long time, but haven't. During part of yesterday's workout, I felt a bit spry, and applied a technique that was reinforced when I was in the weight room on Tuesday. I did a set of lat pulls, and reminded myself to keep my shoulders down and back, instead of extending my shoulders. The idea is to activate the lats on the motion, and not the start the motion with the relatively weaker smaller muscles like the delts.

Translating this to Swimming terms, I thought about keeping my shoulders down on my free pull, instead of extending too far on the reach in front. On a few 50s, I found I did a pretty easy set of repeats holding :30. It made sense to me to start the catch with the shoulders not as extended, because it's a stronger movement that way. The result was the breezy swims.

So, today, I thought about doing the entire workout aerobic or higher intensity aerobic, including warm up, to reinforce this technique. I was going to repeat it as a mantra: "shoulders down."

The result was that I did some moderate 300s on 1:20 pace (yards), and even the first one, without a warmup, was 3:54, and the snorkels were about 3:55. When I added a stronger kick on a few, I was 3:40, with an HR of probably no more than 140.

Yes, I added one more half-cycle to each 25 (from 14 to 15; 13 to 14 with paddles) but I was faster with a bit less effort. I'm looking forward to my next session, probably Saturday, when I'll try to add some speed swims with this technique.

You got out on the opposite end!? Actually, I think I’ve done that.

When you are trying to lengthen your stroke, you really extend your arm. It's like a kid in class answering a question by raising a hand very high up ("What's the capital of Burkina Faso?" "I KNOW! I KNOW! It's Ougadougou!"). In the pool, if you extended both arms for a far reach in front, your shoulders would go to your ears, ideally, sort of like the ideal streamline.

What I tried to do:
1) In the weight room for lat pulls, I grabbed the bar, sat down and braced my knees, then positioned my shoulders down and a little back, so that my shoulders didn't go up to my ears.
2) In the pool, I tried to replicate this position of my shoulders, and tried to recover my arms without over-reaching too long in front. The stroke felt shorter, and I tried not to get my shoulders too far forward. I did need to synch the hip roll a but faster to match the tempo, but I don't roll too much, like is perhaps taught that there must be an over-emphasized roll.

The idea is two-fold: get into a catch more directly by not reaching in front, and therefore involving the lats earlier in the stroke, and relying less on the delts and biceps to start the catch. Second is to try to reduce the dead zone in the freestyle cycle with a quicker catch and less length and glide.

When you are trying to lengthen your stroke, you really extend your arm. It's like a kid in class answering a question by raising a hand very high up ("What's the capital of Burkina Faso?" "I KNOW! I KNOW! It's Ougadougou!"). In the pool, if you extended both arms for a far reach in front, your shoulders would go to your ears, ideally, sort of like the ideal streamline.

What I tried to do:
1) In the weight room for lat pulls, I grabbed the bar, sat down and braced my knees, then positioned my shoulders down and a little back, so that my shoulders didn't go up to my ears.
2) In the pool, I tried to replicate this position of my shoulders, and tried to recover my arms without over-reaching too long in front. The stroke felt shorter, and I tried not to get my shoulders too far forward. I did need to synch the hip roll a but faster to match the tempo, but I don't roll too much, like is perhaps taught that there must be an over-emphasized roll.

The idea is two-fold: get into a catch more directly by not reaching in front, and therefore involving the lats earlier in the stroke, and relying less on the delts and biceps to start the catch. Second is to try to reduce the dead zone in the freestyle cycle with a quicker catch and less length and glide.