Thanks for the replies guys. I have been running for 3 years but had a baby 4 moths ago so I'm not doing a high mileage just now. I already land on my forefoot and always have done although I didn't know this until I was getting gait analysis for new shoes. I've also been told I have a high candence by other runners but I've never bothered to count, I am always injured and not very fast though so neither if those things can be much help to me! Anyway I'm having a read through the book but it seems to be quite involved and I barely have time to run as it is just now, never mind filming myself and doing a lot of other stuff so if I ever make it through the book I will maybe implement what bits I can and see if it helps.
I just wanted to update this to say that this problem suddenly disappeared. One day I couldn't run much faster than a 12 min mile with my HR sky high and the next day was managing 10 min miles again and can do speedwork and things at the speeds I would expect and my heartrate goes up and down as it should instead of just rocketing up snd staying there. Very strange. I had a good consultation with Dr Google and I think my thyroid might have been a bit out after having my baby and it was affecting my heartrate. So hopefully that's the end of it!
I bought a book that came up on my Amazon suggestions called The Running Revolution. I started to flick through it today and it turned our to be about Pose running and apparently I need new shoes.. So is there any point actually reading the book if it means I have to buy new shoes to find out if any of it will make me an amazing runner or shall I just use the pages to line litter trays? Anyone who has tried pose running and/or minimalist shoes please share your experiences?!
Thanks everyone, my diet is ok not quite as good as pre pregnancy but I always make a point if eating 3 healthyish meals a day and I definitely get all the calories I need. Breastfeeding makes me ridiculously hungry. I had a really easy labour this time round, a quick homebirth with no complications. And I know my irons not low because I've had a blood test recently and it was fine.
I think you're right Trogs and I'm going to have to back off a bit and go back to the beginning again. Work on trying to get some base fitness back before I try to push myself. I had my heart set on doing a half in the spring so maybe my expectations have just been too high!