I began running in May this year when we bought a treadmill, doing 2.5-3k runs and building up to 10k in the last few weeks. I started running outside 2 months ago doing hills/sprint/jog round the park once a week, but the bulk of my training was on the treadmill set on at least 2% incline. The only actual road I had done was one 3k.
My 10k treadmill time (2%) a week ago was 44:50. Yesterday I did the Southend 10k (out and back) in 46:47. I was really pleased with my pacing which was virtually spot on 4:30/km as I had intended by halfway, was feeling ok and was fairly confident I could hang on to finish in 45-ish. But then when we got back onto the seafront the winds had started, and blowing straight into us all the way back! I started to tire at 6-7k (I do on the treadmill too) but with the winds was unable to hang on. It was equivalent to going along (treadmill) at 2% then at halfway someone coming along and turning it up to 3%.
My verdict is that road is equivalent to 2% treadmill, but only if the weather conditions are ideal. Forget boredom/lack of scenery etc, when it hurts that much, nothing helps.
The next race for me is Brighton 10k towards the end of Nov. Same out and back. I really want to achieve 45 mins but I realise the conditions at that time of year probably won't be great. I intend to do 10k's on 2/3% combination, progressing onto 3%. I will also do intervals/hills both on the treadmill and in the park at the weekend, weather permitting. I want to get over getting tired at 6-7k. I think my legs let me down the most. Advice needed please.