My running background
First off, I am a "native" runner and have been racing since I was 10 in running races. By native I mean that was my first and prime sport. I was not very good as a 10 year old but I was either last picked on the team sports or really sucked. Running clubs let everyone in and that was important to a nerdy geek like me.
By the time I got to grade 8 I was no longer the last placed runner in running races and it was helpful that a year after I started running I also joined the local swim club. I think it helped me develop my cardio up.
By Grade 10 I was now competitive, not the elite but one of the better runners in my age group and qualified for high school cross-country provincials (for the American`s it would be our version of state championships) and finished respectfully. I later ran in college (while attending SAIT Polytechnic) and at University attending UofCalgary.
Some 30 plus years later I am still racing and enjoy my "running" heritage. In the triathlon scene I enjoy the edge in the last leg of the race being on the run.
My favorite run workouts
#1) 1 mile warm-up, 5-10 X 1 mile intervals with 3:30 rest, 1 mile cool-down
#2) 1 mile warm-up, 8 X 400m repeats with 2 minutes rest, 1 mile cool-down
#3) 25km easy run
For the longer run I recommend following the Mark Allen heart rate approach initially when it comes to heart rate on the long runs, then eventually going to what I have heard attributed as a Kenyan model where the first 75% is easy and the last 25% is at marathon race pace.
For me I have found the Hal Higdon marathon training program has worked best although active.com has a good article on marathon muscles development. They also have a reasonably good top 5 tips article as well. For stats geeks you can go here for a race time prediction tool
Ironman focused long-run training
One solid IM focused longer run workout is to run a 2 to 2.5 hr run with a 20 minute tempo section at your Half-marathon (non-tri) pace with the rest of the run at the IM pace.
A true brick is several bike/run combos. One triathlete suggested that you "go to a track. take bike and bike trainer. Set the bike up on the infield next to a gate with bike stuff out just like a transition area. Do a 1 mile warm up (run) then the fun begins. Go run 15 min. about 50%-60% effort than do a quick change and ride the trainer and ride for 20-25 min @ 60%-70% effort this is 1 set. do 4 sets"
I recommend do this on a weekend day and not after a hard ride or run the day before. Please adjust to your own time factors and ability levels.
Also there's a brick workout but just doing a ride and run back to back is good for your legs getting them used to doing this, I always try and run and ride the same day even if its only a couple mile either way.
More bricks or longer tempo runs where you work on negative splitting will help you get used to the Gumby feeling. Also you may find running easier effort in the first half of runs the most useful way around it and then pushing the second half once the legs are fully back.