How much running do you do in general, BlueToff? It sounds like you're fit, are an experienced runner, but then you say stuff that sounds more like a beginner - 2.5 mile runs outside are hitting you hard? 50-55 min 10K for a young, experienced runner is also pretty sedate. I'd aim for this if I was doing a 10K next month, and I do next to no running and am a lot older and fatter than you.
One thing that is in vogue for cycling, and probably holds for running to, is that your easy rides are too hard, and your hard rides are too easy. Avoid grey miles. In other words, always going out and going moderately hard is a poor way to get race fit - you need to bury yourself on an interval day, and go very easy zone1 or 2 on other days. Like a 5 mile run just ticking over and not breathing hard at all.
Yeh, this is the thing. I went to the doctors about it back in May but they just fobbed me off with a blood test and couldn't find anything. I've had that on and off over the past few years. At times I'll have bags of energy and will feel just fine, and others it's a genuine struggle for me to get past the 3 mile mark. At the moment I'm feeling good, I just haven't run an entire 10k in a fair while so I'm keeping my expectations within reason.
I do my interval training in the gym on the treadmill (usually, sometimes I mix it up on the bike and rower). Usually 30 mins including a 5 min warm up and warm down, and then intervals of a minute each, at an incline of at least 2 to 3. That's my hard push.
I like to mix it up on the treadmill and also do a bit of a bleep test type exercise (i.e. build up the pace in 30 second sections, usually over the course of about 5 minutes).
Thinking of the toning up really. I've been increasing my weight and core work, and like I've said, I've definitely shed a bit of weight off my legs in recent weeks as well, the clothes fit is always the best measure of that I find! I just want to try and burn through this half a stone or so without having a diet that is going to leave me with less energy for my training.
It also doesn't help that I have to eat about 5 hours before I run/work-out. If I have a sandwhich or anything carby at lunch, forget about it, I won't be able to run until about 8 that night. It's bordering on ridiculous. So if I'm tired from lack of sleep or work piling up (which with two jobs it can do), not being able to eat anything substantial in the build up to a workout is a bit of a nightmare.
Anyway, wary of coming up with excuses! Thanks for the tip on the grey miles and running routes. Will try that out!