Injury prone ultra runner

Hi folks, I have started training for Compton Downland Challenge 40 miler taking place at the beginning of April when I came down with plantar fascitiis. Not sure yet of diagnosis as seeing physio on Thursday but pretty much sure this is it. Anyway, I find it rather hard to string together uninterrupted training time as every so often I go down with something. Last year I only started running again in November after being off for 4 months with groin strain. Then in March I got shin splints. I started working with my current physio, got new custom made orthotics and things were going well til June when came down with adductor strain which took me 2 months with hardly no training. In August I also got plantar fascitiis but mildly and was running again at the beginning of September. Mid October I did a marathon, then took 4 weeks recovery time with low mileage and since mid November started training more seriously for this race with an online coach. Last Sunday I did a xcountry race and afterwards could feel the pain. I tried to run through it but it was agony after 5-6 miles, now stopped.

I'm quite aware I have issues from birth with biomechanics but feel it demotivating and frustrating to be going down with something every few weeks. I'm no quitter but I'm starting to feel that maybe I shouldn't go for it and do low mileage and run on country tracks and have no ambition to do an ultra. A big voice in my head tells me to carry on regardless, get better and get back to running again whatever it takes. Any advice here would be welcome as not really sure whether I should press ahead.

Agree with Lirish.  Have you really looked at why you are constantly injured?  You say you have issues from birth but has your physio tested where you are weak/strong?  How is your core stability/strength? If you are weak through the core with an unstable pelvis this can cause all sorts of issues which you would not necessarily seem to be a core related issue.  Just as an example (and I'm completely stabbing in the dark here!!) - your shin splints.... weak glute med and adductor muscles can cause excess rotation of your leg causing over pronation, leading to shin splints.  Orthotics correct the OP but the underlying cause is still there. 

You say you have issues you were born with - but your body is very clever at adapting to what it's got if you build up the right areas to support problem areas.  I don't know ACDC - with all your injuries something is not right but as someone who also is challenged by biomechanics  I'm pretty sure that running IS possible for you with the right advice.

I had PF and was out for 2 years, firstly because I ran through it, not realising what was going on (I have an extremely high pain threshold) and then because I tried to return before I was ready.

I have bio-mechanical issues, wear orthotics and can now run, pain and problem-free.  So, as TL says above, it is possible.

I'm happy to let you know what worked for me, if you want me to pm you I can, as it's a bit long and boring for a forum and I've posted a lot in the past on the PF threads.  Unfortunately, the only real thing was rest, which is not what I imagine you want to hear.

I have no idea what your training schedule is like, but sounds as if you need to scale it back a bit, sort out and address the issues, then start again.

When I was first treated for PF, I was told, you'll only ever manage 5 - 10k's - now I'm training for a mara - but it's been slow and sensible. 

You might need to adjust your longer term goals, not necessarily give up on them, but just adjust them and then come back to them with a different approach.

Thanks for the latest response. For the last month I have been attending The Running School, they are teaching me how to run biomechanically effective, my running style was very poor. Relearning the correct way to run is quite hard, it will take me a while, first events planned now are Berlin marathon in September and Druid Challenge in November. Even though I had to postpone my plans for now I am having fun doing what I am doing and working with this coach. Hopefully I shall be here later on this year to boast I have completed my first ultra.