I recently increased my volume from average of 8000yards per week to 11,12K. I noticed last week my left arm was sore during the pull phase of my freestyle stroke. I can't pin point where its sore but it feels like below the shoulder (tricep/bicep area). But not entirely sure. It doesn't hurt at all after swimming and I tried pressing all over to see if I could find a sore spot but I can't. Its definetly worse this week and my swim times are dropping because I'm losing power in that arm. I heard that usually the shoulder/arm is sore on the opposite side you breather but not the same side. Any clues? Should I just take 3-4 days off or cut volume down? I have an ironman in 3 weeks!

I took off Wednesday-Sunday from swimming. I swam today but after about 2000 yards I started feeling the same type of soreness. I only feel it when I am in the pull part of the stroke. I never had any issues before and I swam more volume last summer with my build up. I am swimming harder and pushing myself harder but I would figure 5 days off swimming would help. I did 1000y WU, 10x100 all out and 12x50 all out today. Am I swimming too hard? Could it be my bike position when I'm on the aero pads. I noticed that my left aero pad (side of arm soreness during swimming) is slightly lower then the right so maybe the added pressure on the arm is causing it?

I don't know if this is necessarily your problem, but when I pool swim, I constantly get a sore shoulder if I exceed 10k yds per week when breathing mostly to my stronger right side.

It took me awhile to figure out what motion exactly was causing the problem. It actually was NOT the most obvious culprit, meaning straining the shoulder from pulling too hard. Weirdly, I could use paddles all out and not make it significantly worse than swimming the same distance easy stroke (which often made it worse.) Very frustrating, as it actually became my main limiter in swim training when I wanted to ramp it up.

Turns out it's almost definitely the hi-elbow recovery part of my stroke. I only figured it out after using my Vasa swim trainer a lot, with sprints and super hard-effort pulls, and more volume than I did in the pool, yet having zero shoulder issues whatsoever. And I don't do some crazy high-elbow - in fact, my self-taught recovery phase of my stroke is likely a lot lower than the 'correct' method (I took a swim lesson with a high-level coach a few times, and he really emphasized a super high elbow recovery for me, unfortunately, which REALLY makes things bad for me.) Turns out this actually happens to other folks as well, at least according to the Vasa manual, since you can completely omit the high-recovery portion of the swim stroke on a Vasa trainer. (I suspect most Vasa users actually use it this way - doesn't seem to adversely affect in-water swimming whatsoever for me.)

It was counterintuitive for me, since you'd think the hi-load portion of the stroke would be the most problematic, but at least for me, it's the no-load recovery portion that seems to be a big problem. Makes me wonder if I have a labral injury on that side.

At least for me, right now the unexpected solution is to do the bulk of my swim volume on the Vasa trainer. Not saying you should do this as well (it's $$$), but it may be worth paying attention to the recovery portion of your stroke and seeing if modifying it reduces you shoulder pain.

@ Ericmulk -
I think you're misinterpreting my post. The Vasa completely relieves the pain of my shoulder because it omits the high shoulder recovery. And since that's a no-load portion of the stroke, it has no adverse effect on my pool or OWS (I was a bit surprised at that.)
I had some really bad shoulder problems BEFORE the Vasa, definitely anything over 10k/week. I toughed it out at one point to see if it would go away, and it got so bad at one point I couldn't even raise my arm over my head without severe pain. (I think I inflamed the shoulder from ignoring it.) Since going Vasa, I have had literally zero shoulder pain except for the rare pool session where I'll go 3000+, and it'll start reappearing. Absolutely zero shoulder pain on the Vasa, even when doing stuff like max-power 100m sprints, 30 of them in a row.
In terms of my swimming improvement, I've been very happy with it in the 7 months since adding a lot of Vasa to my regimen. I looked at my logs for the last 7 months and I was averaging 4-5 hours per week of 'swim' time, on average 3.5 with Vasa and 1-1.5 in the pool (max pool sessions were 30 minutes, due to it being my lunch break.) Not a ton of swimming, but given I was biking and running 10 hours on top of that, it was very significant for me, as I usually have to shortchange the swim a lot when I'm race prepping and biking/running a lot. My pool times have also dropped significantly - I did one masters workout with a triclub 2 weeks before my race and swam the entire 3000yd workout at my 200yd max pace from last year, never swimming slower than 1:30/100yds. The added volume has allowed me to break through an annoying plateau that I was stuck at prior to getting the Vasa.
Without doing any added intensity, I managed to drop 2 minutes from my HIM swim time that I did a few weeks ago. I'm still a MOPer only, and clocked in at 34, but that's a huge improvement from last season. Even better - I was totally fine on exiting the water, as opposed to feeling gassed last year at 2 mins slower. And I can pretty much credit the Vasa with pretty much all of that, as I have been in the pool the least I've ever done since getting the Vasa, and have never exceeded 2.5hrs of pool time in a single week, and averaged close to 1-1.5hrs per week of water time as said above. In fact, almost all my pool time was NOT hard workout sets, but actually technique refining, to make sure my Vasa form was being translated to the pool. (It's nearly impossible to do hard 10 x 200 sets when there are 3-4 noon swimmers, at least one of whom will be 1:50+/100) so literally all the fitness I gained was Vasa gains.
And the fitness component can't be underestimated, even for MOPers like myself. It's stunningly obvious even to me, that my arm endurance and ability to repeatedly pull hard is SOOO much better than ever. It's so much better than I can intentionally screw up my technique, or sight like crazy with head out of water, and still smoke my old self. I think triathletes also really underestimate how effective swim volume is - the Vasa isn't some magic device that allows 'super training', but it's a device that allows you to put in quality volume (and intensity if you'd like) without the pool.
Again, I'm really surprised how few people have this device on these forums, considering how many people who complain about their swim underperformance don't even hesitate to drop money on multiple Zipp wheel sets and Quarq powermeters. Maybe everyone else just has way more pool time and pool acessibility than me, but for my busy schedule and limited pool hours (of which it's almost always a crappy circle swim with recreational swimmers at the Y), the Vasa has been my best tri/sports investment - it's been a lot better than I expected, and good enough that even if you offered me an endless pool or in-ground pool, I woudn't take it, as the Vasa is completely maintenance free and works so well for me. I used to constantly stress about swim training and how to fit it in, and how to work around the slowsters in the lane at lunch, but now that stress is completely gone.
Yes, I'm shilling for them, but I'm honestly not trying to oversell it at all - it really does all that I've said of it.

I breath naturally to the left, and when I swim a ton my right shoulder gets tired first. To counteract i have (especially this year) concentrated on bi-lateral breathing.
- I swim bi-lateral in warm up, but...
- I tend to go back to breathing to one side when going fast/sprinting, or the interval is very tight.
- In mid distance sets (400m) I try to do the first 1/2 bi-lateral, and one side for the last half.
- Open water I do as much bi-lateral as the conditions allow.

I've found bi-lateral breathing is the secret to making sure both my shoulders are fatigued equally. :-)

(If they don't I am clearly not swimming enough.)

@ eric - I hear you on the delt fatigue due to Vasa, but I actually think it's much smaller of an issue than you say it is.
One of my biggest worries with the Vasa at first was losing the natural motion of the elbow recovery, or early fatigue once in pool/OWS with the arm recovery. At least for me, it takes minimal pool time (like 30 min per week of easy swimming) to maintain it, probably because it's a 'no-load' portion of the stroke.
I would however completely agree that a college swimmer on Vasa who went back to 60-80k/wk in the pool, would likely really feel some delt suffering! At that volume, you really have to have the delts plugged in as well! (I can't imagine anyone would go do over 20k/week on the vasa though.)
Thanks for the helpful insights though - always like hearing you chime in

I swam open water again yesterday....2000 yards with no problem. I didn't push too hard though. I did notice my arm was sore on my long bike ride. I notice it when I'm climbing hills and pulling on the bars. Maybe I'm over thinking things....