I've been running 4-5 days a week for over a year and swimming with a team 3 times a week. I've also competed in both sports. For running I've competed several in 5 and 10ks and a half. A lot of the training plans I've seen for introductory triathlons have significantly less activity than I already take part in. My swim team practices last 90 minutes, whether I want them to or not. My running is also only 45-60 minutes of typically low HR type training (Maffetone), so I think I can still do it without risking injury. I HATE biking. I'd like to only bike a couple times a week. Does anyone have an idea where I should start trying to find a plan or if there aren't plans if you already have set practice schedules and can't change them.
I don't think that you need an actual plan to do a triathlon. I am a swimmer (competitve in HS and college 30 y ago) and have been running the occasional race in the past 10 years. I decided this year to try a triathlon (on the urging of my friend). So I dusted off my bike-having ridden very little in the past 15 years and started riding. I picked a sprint triathlon to shoot for, a 1/4 mile swim, 13 mile bike, 5K run. I have been swimming 2x a week for the past 2 years, doing 1200 yards or so, so I didn't change much about that-except for doing longer repeats. I tried to ride the bike for a long ride 1x a week (maybe 10 miles) and I did several "bricks" which is a bike/run. I would bike 5-7 miles and then immediately run 2-3 miles. My legs feel terrible but it's good to do so you know what to expect in a race.
So what I would do if I were you, is pick a race to shoot for, get on the bike and give it a shot.
Tri the Lake Wakefield MA 6-25-2011 (aborted due to thunder, but was first in AG for the swim)
Cranberry Trifest Sprint Triathlon 8-27-11 (9/15 in Age group)
Lower Cape Triathlon 6-22-13
Dam triathlon (Amesbury MA) 7-13-13
When I did my first tri I had already been running races for years and had been swimming with some competitive swimmers for about a year. I was feeling the same as you when I looked at the beginner training schedules because they weren't up to the level that I was already at for running and swimming. I started with a sprint race but picked a training plan that was labeled "advanced" (I think it was for people who were looking to improve their time). It was actually one of the plans you can buy from Active.com for ~$30. I printed it out and used it to train for the next few races I did as well. I agree that you can train for your first tri without a plan, but if your like me its nice to have some kind of structure and guidance at least to get you through your first race. If you don't want to pay for a training plan, search online and you should be able to find some free plans - just keep searching until you find a plan you like.