Could you do 85% of training for marathon on a treadmill ?

So a brief history of me,

Im now 34 started to train for the Belfast marathon in 2010/2011, I started from only doing a bit of walking and training went well.

Sept and Oct built up to be mainly 2.5 - 4 Mile runs with a long slow Sunday run of 7 – 8 miles.

During Nov I was on hols so missed most of this month

Over the winter I joined a gym and used their treadmill for Dec, Jan. I was doing the same routine and miles but knew that treadmill was easier than road running.

I also got a personal trainer an hour a week in Jan/Feb to help work my core.

When I got back on the road in Feb I surprised myself with what I could do, my weekday runs were getting faster and during Feb – Mar I managed 11, 13.3 and 12.1 mile runs at good speeds, I was feeling good after each run and can even remember saying to my wife I think I’m going to be able to do this!!!. ( I managed to find my post saying about it on here http://www.runnersworld.co.uk/forum/beginners/just-ran-my-first-half-marathon-distance/171893.html

My next run after my 12 miler I got a few miles in and one of my knees started to hurt and I had to abandon the run half way in. I rested a few days then tried again and same problem.  I then rested about 2 weeks and again about the 2 – 3 mile mark knee started hurting.

At this stage I pulled out of the marathon as I was now too far behind and I didn’t want to cause further injury. Since I was pulling out I felt down and just gave up so never seen a doc about it. Even now i can’t even remember what knee it was and if the pain was inside the knee or at the sides etc. However it did only hurt during the run and maybe a few hours after.

Over the last year or so I have lost 90% of my fitness but go out for a short run/walk every now and again. Sometimes I get niggles in my knees but I don’t know if it is just my imagination looking for the problem or if it’s just normal hard work pains.

2 Weeks ago I bought a treadmill and have been really enjoying running on that again. I’m up to 3 miles and not a single pain in my knee (I also can’t remember getting any pains when on the gyms treadmill). Also I have a TV positioned in front of me and the room is separate from the house so I’m not going to disturb anyone, so I could run for a long time etc.

So I guess I’m thinking is it possible to do, let’s say 85% training on a treadmill then the other 15% on the road, just so I can save my knees? I would still love to get 1 marathon done in my life time and I really do love the feeling of being fit, but I guess I’m just scared of doing long term damage.

Any running is better than no running, but to do 85% on a treadmill won't compansate or replicate running on the road. I gues you'd probably need ot build up your fitness on the tready and then try and wean yourself off? Are ther any parks nearby where you could run on gras instead?

oh my god, why would you want to? unless you're under house arrest, or you're Will Smith in "I am Legend" I couldn't imagine why it would be preferable to running outdoors.

Ultra you make a good point about the shoes, I wore my normal trainers to the point of my knee hurting. It was that that made me go to a proper runjing shop and get fitted out, but I still had the problems a month or so later.

Knight, that could be a good idea, building up the general fitness over winter then build up on the road running.  I have no good parks localy but there is a good area a few miles away, its a couple of football pitches and I know its 1/4 mile per lap. So not the most interesting place but the times i did run there i found it a lot easier going than the road running.

I think one of the problems is also the road/path conditions around here, not in good condition and a good few are on a slope.

AgentGinger its not preferable, I loved running in the wet and wind etc but just dont want to cause myself another injury and get downhearted again about it all.

I had knee problems 3 or 4 years ago - I'd strongly recommend seeing a physio. I slowed down, did the exercises and stretches he recommended and my knees have been fine ever since. I stretch religiously after every run.

As for the treadmill, I do about two thirds of my training on one. To give you an idea of my mileage: I'm currently trying to move from 30miles pw to 40mpw with thoughts of doing my first marathon in may next year. I expect I'll still be doing over half my mileage on the treadmill. Lots of people seem to dislike them, but i find I just get into the groove and let my mind wander. And no dogs, dog sh!*, kerbs, cyclists etc to trip over.

I like doing interval training or faster shorter runs on a treadmill, particularly as you can follow up with weights after if you have the energy. But anything longer than 45mins on a treadmill I find deadly dull. I also find I get sorer joints on a treadmill. And its always too hot in gyms. 

Did you do any long runs on the treadmill.......you say for the first few long runs you felt great........did you perhaps get carried away with the good feeling and start running the longer runs too#fast.they are suppossed to be slow......

it could have been that you started go faster at the same time you were pushing up the mileage and did too much.......

I would try and do at least half outside and build up slowly from now.......it you run all of them uinside and then try and do a marathon outsifde there is a high chance of injury......

I think its importsnat to do the shorter runs outside now to give your body a chance to get used to it......

good luck