Cutting back on lifting...

Without knowing what your goals are, that is a tough question. After a year of tri training, I am doing just the opposite. For me (and maybe just me because I am a bigger guy), I have gained weight from strictly cardio workouts. I need the resistance training to keep my metabolism up and burning calories all day! So, if you are looking to SBR faster, then SBR more. If you want to lose weight, don't cut out the wieght workouts.

just my .02

I've you are going to go to one day a week, don't do the sissy weights with high reps.  Go really heavy with low reps (like 8) and hit the whole body.  

Maybe I'm just cranky because I'm in the middle of this really strict diet, but man do I get tired of these weight lifting myths. And it's not your fault - you obviously heard it from someone who heard it from someone, who didn't know what the heck they were talking about. Here's the scoop:

To gain mass/bulk, you need a high volume of training plus surplus calories. Now, how much surplus calories to take in is up for debate. In the past, bodybuilders would eat anything that wasn't nailed down, gain a ton of fat along with the muscle, then try to cut down for a contest. These days, the prevailing wisdom is against such massive eating due to the fat gain. Still, it's hard to gain lots of muscle when your caloric intake is around maintenance. Building muscle also requires recovery. You don't build muscle in the gym; you build muscle when you rest. And the more exercise you do, the harder it is for your body to recover. If I put you on a high volume bodybuilding program along with same volume of tri training that you're doing now, I would bet big money on the fact that not only would you not get "all bulky," you would actually lose muscle mass! How can that be? Because lifting weights tears down the muscle tissue, which is then rebuilt bigger and stronger during recovery. If you're constantly exercising, your body literally can't "keep up" with the muscle damage and the result is an actual loss of muscle tissue. So much for lifting heavy makes you bulky. On a side note, if I put you on steroids, that changes everything, but we won't go there.

As for your question, if you want to maintain your strength levels and the muscle mass that you have, lifting once a week will do that. But that's all it will do. The HIT Jedis notwithstanding, lifting once a week is not enough volume to stimulate muscle growth.

I had a pretty successful winter of overeating and lifting 2x a week.   I gained about 8lbs of muscle and 4 lbs of fat, according to my calipers and scale.  Cardio volume was fairly low (2-2.5 hours a week).  I did the same lifting workout every time.  I did 1 set of 8-10 per muscle group and an additional set of pullups and pushups to failure.   Soreness was horrible for first 2 weeks, but then it wasn't enough interfere with tri training at after that. 

I do have the body type to pack on muscle and fat at will (Getting it back off is another story).  I am 215 and 18% BF right now, so no fitness model for sure. 

I would say that 2x a week is fairly low volume for gaining BUT I don't know what you were doing for those two days AND body type does make a huge difference. I'm like you - I put it on easy but taking it off is near impossible. Most people on weight lifting forums avoid cardio like the plague because it will zap all of your muscle gains and you'll waste away to nothing. Not a problem with me. And even if that happens, "lost" strength is much easier to regain, especially for guys like us. I had to lay off lifting heavy for most of last year because of my back, but this year I'm better and although I'm not yet lifting as much as I was, I'm able to pile on more plates each workout. It's kind of nice.

Just out of curiosity, as cardio increases, it becomes harder to put on, or maintain muscle size with strength training due to the extra calories needed, as I understand it. Does this go for strength as well? ie. 1RM strength? As muscle size does not directly relate to strength (correct me if I'm wrong)

 Just throwing this out there, as you seem fairly knowledgeable, MiketheBear, or anyone else who knows??

You are 100% correct - there are lots of "skinny strong" guys out there. Strength is as much, if not more, about the nervous system being able to recruit all of your muscle fibers as it is about muscle size. Basically, the average person sitting on the couch can only recruit a certain percentage of his or her muscle fibers. Put that person on a a weight training program and their nervous system will become more efficient and be able to recruit more fibers. Hence, the person will become stronger without actually putting on any muscle mass. Pretty cool. Pavel Tsatsouline wrote extensively about this in "Power to the People." A decent book but pricey. Worthwhile to borrow a copy, though if you can.

Can you gain strength while doing endurance work? I would say a cautious yes but you need to be diligent about it. Doing strength and endurance places somewhat conflicting demands on the body. Endurance work requires a very low level of force production, hence, no reason for your nervous system to recruit lots of muscle fibers. Actually, your fast-twitch fibers aren't recruited at all, unless you like to sprint to the finish. When you do strength work, your asking your body to turn on lots of muscle fibers.  Tsatsouline's "Power to the People" outlines a program for "strength without size" that may work for an endurance athlete who wants to maintain or even gain strength. You focus on only two exercises, you do only 2 sets of 5 reps, but you do this almost every day. It sounds like daily training is a lot of work, but not really based on this system. It's designed to keep you feeling "fresh" and to train your body to get the proper feel of the movement which, in turn, leads to that neurological efficiency that I talked about.

I'm doing low reps/high weights with lots of functional exercises (pull-ups, push-ups, bodweight exercises) and core work. It's really helping me build muscle endurance. 

I'm planning on switching to Simplefit and core work for maintenance when my training volume starts to peak. I think that I'll give Crossfit a go after tri season.