i did pick up biking a few years later...at the time I would have told you the biking helped my running, but truthfully I have to agree with Jon Orange - there is something about the motion that just didn't translate to running for me. I was still fit and only running 20 miles per week at that time while I was 1/2 ironman training, but when I showed up to do a road race I just wasn't fast. Rowing may have been helping more because it was both stretching and strengthening my legs without bulking in the wrong way.
Just to give you a little more overall of what I have learned that worked for me and what didn't.
after having that really amazing stretch of racing for 9 months - I began to go back to longer slower training (invited to run USA national marathon champs) this was based on my 20K time = 1:03 or about 1:06;30 for a 1/2 marathon...but I had never done anything over that 20k. Starting upping my long runs to 20-22 miles, then hit a snag - shoes that I was running in changed the way they were being made and I couldn't go more than 8 miles and even that was bad - sore thighs (weird motion) - they started ruining running shoes in the late 80's with motion control and extra support and all that crap that was supposed to make them better. Because I couldn't find a suitable pair of shoes, I actually switched sports to triathlons.
after triathlons turned into a money sport (that is you have to have money to compete in them) in the mid-late90's I began a switch back to running on low mileage still not able to find a suitable running shoe. Finally I settled on just doing all my mileage in racing flats - over time I realized I could do long runs again and even more crazy was I would be less sore and less broken down by running in racing shoes - now that is all I run in.
but I was still trying to run everything too hard near 6:00 pace or better....after some convicing from internet folks I tried a more Hadd like approach. it was brutal at first having never really done slow fat burning running before (even when I was ironman training I did everything hard: I would do a brick: bike/run workout every other day and lift/swim on the alternate days).
Got my long runs up to 20 then to 30 over the next year and 1/2. My mileage went from college high of 105 to 116...then 140...160...maxed out at 200 2 summers ago. Coming off that my fall training was incredible: I could do so much more volume than ever before like 16X 800 on short rest...could not believe how quickly I could recover and this was at the age of 49. but got hurt by winter from back pain...still have it but learning to fix it. another injury Achilles killed my summer last year though I ran though it - wasn't able to go much over 100 per week last summer....but finally I am healthy and am getting my speed back (that is the main thing I lost during my slow mileage phase). of course some of that was due to the aging body...now I try for more balance longish runs 16 but not at super slow paces - now I am pushing the easy days to sub 7:00 at least while the weather is good. the other days are tempo focused with some intervals 200/400's.
what doesn't work:
* too many hard days in a week
* trying too hard vs, running the pace that feels good
* going faster vs, just a little slower but getting more volume
* linear thinking (progress doesn't always come in a nice straight line)
even in workouts the goal is not to be faster than you were the last
time you did this workout
what does work:
* being fresh on fast days
* stretching, rolling, etc
* some speed is needed: but start gradually on 1st interval and get faster
(progressive workouts vs. dying workouts)
* patience (it happens over time not over night)
* experimentation vs following that everyone else says