In the winter I tend to focus more on speed than distance. Given that the weather is usually less than ideal - by focusing on harder, more intense workouts - but of the shorter variety, I find I can get the most bang for my buck. From a running standpoint, things like intervals and tempo runs will have an INCREDIBLE impact on your times. It's really amazing. For running, everything breaks down to two pieces really:

1) Can your legs run the distance
2) Can your lungs do the distance at X pace

The legs part is generally easy - it just hurts. It's the lungs part that's more tricky, but doing tempo runs/intervals - you get your lungs used to working at a given lower pace - thus lowering your overall pace.

Focus on improving technique in all three sports and increasing muscular strength through the off-season. Do almost no high intensity aerobic work. The benefits of interval or tempo workouts will be long gone by next season and you'll use up resources that you should be saving for spring.

Most have said it above, but best is by Ken in my eyes. Base is what is now the key. Technique and pick "one" sport and drill it to get the max. out through the season. When we say base what we mean is that one should focus on building the aerobic system for speedwork in the new tri season. By building base we improve many things in our bodies including capillaries, fat burning process, improvements in ligament strength etc., etc. By doing Long Slow Distance (LSD) Long being long hours at low HR we improve these things in our bodies and thus can handle higher intensities when in build phase (higher volume and intensity) pre races. All work should be done at the Aerobic level. That being the AeT - point at which the lactic acid build up is broken down as fast as it is made, usually <70% of the HRmax. Figure that out and the more you can do at this pace for all three sports the fitter you will be come time to train for the races next year.

Read this for a full explanation: Periodization Training Techniques: If you want to improve your performances, you can't train the same way all the time

http://www.pponline.co.uk/encyc/0147.htm

http://www.pponline.co.uk/encyc/organise-your-training-year-with-periodisation-35893

More:

http://www.trifuel.com/triathlon/triathlon-training/what-does-periodization-mean-and-how-does-it-work-000625.php

http://www.markallenonline.com/Base.asp

http://www.markallenonline.com/offseason.asp

Hope this helps clarify things a bit. Good luck!

We have long winters in MN, icy roads and short daylight hours... Somehow I became addicted to weights. I'm not saying it's the best workout for triathletes but I get huge satisfaction out of moving heavy metal. No other athletic endeavor gives me an endorphin rush like weights. I don't think it has hurt my swim or bike time. I'd even go so far as to say it helped. I feel more powerful on the sprint bike (squats) - and even on the swim (pull-ups). I wouldn't recommend it for triathletes at the top of their game, but for this Joe, it works.

Lifting to add strength is a good goal over the winter, because increased strength can really help you in the swim and especially the bike. Lifting to add bulk is not a good idea for a triathlete (though we all have the urge because people like big muscles)

Bulk will decrease your performance in every aspect of the race, and will do nothing but give you a better looking body. Increased strength will improve each leg of your race. And the two do not go hand in hand.

I’m a short, squat guy with a tendency to bulk up quickly. I’ve been an “switch-season” weight lifter / endurance athlete for a couple of decades. Long term strength training (and genetics) have caused me to developed muscle mass that is a detriment to my success as a triathlete/distance runner. I have to caution anyone about mixing the two. If you want to be Dave Scott take it easy on the weights. If you don’t mind being in the middle of the pack there’s no reason you can’t strive for a 13 hour IM and 400 lb squat too.

right now for my first tri, i have done each element twice per week, occasionally throwing in extra swimming because it is relatively new to me and i feel it is a weakness.
from what i read here i should basically keep doing the same workouts but with less intensity...right?

I'll certainly play more racquetball, do more rock climbing and other sports during the off season as Ironmom said. Its a fun time to enjoy other physical activities which you neglect most of the year. And as you get closer and closer to starting the focused training for next year you can get more specific with the run/bike/swim training again to prepare yourself. Its a good time to bike/run to just have fun being outside while maintaining fitness....as opposed to working so hard that you ignore the environment around you ;)

Well, I'm a fan of the show Lost, and sometimes that alone pushes me above 150. Watching the season finale last year was like an LT workout :p But other than that, I agree!

i see the meaning behind what you all say. two things though. 1) I did my first race only weeks ago and it was only one month before that that I did any running or swimming - i'm psyched to continue progressing with this new found love. 2) "the man", lance Armstrong trained year round and found it to be his advantage.