Sweat rate

I know, I know... not the most glamorous of blog titles, but my sweat rate is something I have more or less ignored up until now.
Before my training programme from William and Shaun, I didn't really sweat that much. I got the horrible bright red face and was often forced to walk because I just couldn't handle any heat... but as for sweat, well.. there wasn't really much of it.

Today I drank 300ml of water before I left the house. I should probably point out here that I don't like to drink too much before a run or a race because I spend the whole time needing the toilet. I'm renowned for how much I need the loo, even at work. I do drink a lot though. I've taken to only having decaffeinated coffee, but I also drink green tea quite a lot. Recently, I've been drinking water after lunch too!

As I began my run I felt really good. The weather today was prefect for running as it was quite cool, broken sunshine and breezy. By about 1.5 - 2 miles the sweat was pouring off me and was actually so bad that it was dripping off my eyelashes.
By the first 5K point where I was due to take a drink, I didn't really want one but I took on about 100ml.
I was feeling really comfortable and despite the sweat constantly going in my eyes I felt like the temperature was perfect.
At 10K I took 2 shot bloks and 300ml of water, which meant I had to walk to take it all on. Surprisingly, I really didn't feel the need to walk so as soon as I was done (around 2 minutes) I started to run again.
My next 2 minutes walk was half way up a steep hill and around 250 metres later than last weeks second walk break. I drank about 200ml here and poured the remaining 100ml over my head... still sweating profusely.

It was from here on that the run felt hard, I was mostly running uphill or on an incline and the wind became really strong in my face. I was so relieved when the run was over.
I know I've mentioned it before, but I really do hate this route. I wanted to do it again as a benchmark to how I'd got on last week by drinking 100ml less before leaving the house, and I think I got the result I was hoping for. I also ran last weeks run the fastest I've done this route... today was a further 1 minute 17 seconds quicker!
So, I now think it's time to change the run to something different. Todays route is difficult because more of the downhills are in the first half, leaving the harder parts for the last part!

I've decided that on Monday, as it's a 1 hour run, I am going to work out my sweat rate by weighing myself before and after the run. Like I've said before, I've never felt the need to do this previously.... but I'm now thinking I may have hampered runs in the past because I've started a run slightly dehydrated.

I seem to recall reading that the first 2 or 3 miles is where your core temperature increases. Maybe I'm normally not hydrated enough to counteract this???