Swim Times Slowing Dramatically

Do you have a swim coach or a triathlon coach?

Can you give us an idea of what your current workouts are like? 10K a week is a good amount, but if it's all moderately paced that could be a culprit. Are you doing high intensity interval stuff?

7:06 for 400 is pretty good for a new swimmer. Are you sure that was 400m (not yards), and measured correctly? If you really are that much slower now, all of your workout intervals should be reflecting that dramatic a slowdown. I'd be skeptical of that original 400m time trial length if you haven't seen dramatic slowdowns on your interval work.

Hmm...overreaching maybe? Are your bike/run times showing any change? Do you feel unusually exhausted in the rest of your every day life?

First, let's look at the numbers, because they don't really add up.  Last year you said you did a 400 in 7:06 which works out to roughly 1:46.5/100.  Three years ago you said you were at about 1:58/100 after 2 months of training.  Currently you are at approximately 2:21/100 which does seem reasonable given the training you have outlined.

My first inclination is that the original time a few years ago was inaccurate.  You said "they had an hour swim and I averaged 1:58/100."  Based on what?  If you swam for an hour and they calculated time/100 from total laps it is pretty easy to see where total laps was wrong after an hour.  1:58/100 seems pretty quick for someone that had only been swimming for two months coming from dog-paddling.

Next, I question the time trial last year where you did the 7:06.  Again, that seems a bit quick, given someone coming from a dog-paddling swim background with only a couple years training at +/- 3,000 weekly training volume.  To put that volume into perspective - the year I qualified for the Olympic trials I was swimming +/- 15,000 meters per DAY, seven days a week.  Not saying it was impossible that you swam a 7:06/400 but it seems a bit unlikely.  I think it more likely that the time trial time or distance was incorrect.

My suggestion is two-fold -

First, determine you swim threshold pace.  Another name is CSS or critical swim speed.  That will tell you the pace you can swim for an extended period of time (generally assumed to be up to an hour).  As a newer swimmer, that is also the pace you can reasonably expect as a race pace, including a sprint triathlon.

To determine swim threshold pace, do a complete warm-up.  Then do a 400 yard time trial.  Do not dive to start the time trial; push off the wall.  Ideally you will have a helper record your time.  Time should be recorded in seconds.  After a complete recovery (at least 15 minutes of slow easy swimming), do a 50 yard time trial - record time in seconds.  Both tests should be maximal efforts meaning as fast as you can do the test.

After the test determine your swim threshold pace as follows:  STP = (400-50) / ([400 time in seconds] - [50 time in seconds])

STP will be in yards/meters per second.  To turn that into a usable number take the desired distance and divide by STP.  For a 100 pace that would be 100/STP.  Again, that will theoretically be your pace at lactate threshold, meaning the pace you should be able to maintain for a long period of time.  The test is relatively easy to do so you can easily repeat it every 6-8 weeks to track progress.

Next, I would also do a 100 time trial.  After a complete recovery from the CSS test, do a maximal effort 100.  Then you will know what your best 100 pace is.

Once you have done the CSS and maximal effort 100 tests, you will have established a baseline from which you can accurately gauge progress.  While 10,000 per week is not huge volume, you should expect to see some improvement over time ASSUMING YOUR TECHNIQUE IS GOOD.  If your technique is poor you can swim 50,000 yards per week and may not see any time improvement.

Good luck, hope that helps.

Another quick observation.  If your Masters Coach can't figure this out, you may need a new Masters Coach as this is a pretty easy problem.  Assuming no underlying medical issues, it is either improper time trials, improper technique, or improper training.  Shouldn't be that hard to get to the bottom of.

When we start to feel burned out in our masters group, the general scientific consensus is that some days the water must just be thicker...

This doesn't answer your question specifically, but if I questioned my coach/results enough to go on an internet forum to ask about it, then it would be time for me to find another coach.

Actual race times I usually don't use from year to year because swim courses are often mismeasured. I like to look at where I am relative to others to see how I did. Was I MOP this year and BOP last year, yep then I'm slower but actual time in most tri ows are not very helpful as most courses are measured wrong. Or see what % you are overall, if your AG is small. and how your % compares from year to year.

What stands out to me most is your having trouble making your times in your swim workouts and having to adjust your interval times down repeatedly.

You pay for Masters, I'd ask to speak to the coach or coaches and have a serious conversation about what is going on and your concern. Their response and their plan to help you get back on the right course is key for you to decide what to do.

Maybe get a private swim lesson or two with someone different and see if they see something in your stroke that is off.

they were pool swim races...hard to mismeasure that.