Sub 4 hour time dooable when sunday runs suggests 4.20-30 time.

My long sunday run training times suggest a 4.20-30 time, this is when running jaded as im on a low carb diet to lose weight and have lost 3 stone, so each sunday run im shattered before I start and not fuelled up. Carrying a heavy waist bag with gels water, phone, money, keys etc and in loads of clothing as its been freezing.

 Is it ambitious to think I may do a sub 4 hour run if it all clicks, a weeks rest, proper fulled up and no heavy water belt etc and of course light clothing and a vest.

Also this means ive rarely done a sunday run at marathon pace, the crowd, 4 gels, usually have just 2, adrenaline etc, all will help.

I wouldn't predict a race pace off a training run for the reasons you state - do you have a recent half marathon time to use as a predictor? Try doubling it and adding 10%. I wouldn't recommend a low-carb diet either. Your running performance in both training and racing will suffer if you don't keep your glycogen stores up. I have lost 4 stone in the last year but while I weigh my pasta and rice portions it's not a "low carb" diet, I've just tried to eat less rubbish, and sensible portion sizes. Don't forget that long runs are usually run slower than marathon pace or perhaps with blocks of marathon paced miles. Undoubtably you will run faster if you fuel properly but it's hard to quantify how much faster.

Which marathon are you training for? Do you have time to do a last long run properly fuelled? Or race a half marathon to give you a better idea of a target time?

Good luck - finishing a marathon is an amazing achievement regardless of the time.

if you have done all your training runs on low carb diet.......i would be worried how the body will react to a sudden large increase in carbs for the race....bit like trying something new for race day....

good luck

Thats fine, ive had carbs on a saturday, before a long sunday run. Ive not cut carbs out, done 2 marathons before.

i knew you had done them before.....just the low carb was worrying but great that you have trained on them the day before.....

If you are doing London the crowds can be the biggest problem.if its another one then you should have a great chance of getting it

How did it go, Mark?

Total disaster, going to put a post about it, im gutted.