I'm about two-thirds of the way through a clinic to prepare for a half marathon on April 26. Most of the group is running in another event two weeks later, so I have to kick up my distance a bit compared to them.
This is my first time training so intensively, and running so far, so there is a lot to learn. Yesterday we had a speaker who has coached many half marathon clinics. He said "you can fake it in a 5K or 10K, but you can't fake it in a half."
Mainly he talked about heart rate training. It is possible to lower your resting heart rate (what you experience when you first wake up) which improves your capacity to increase your heart rate in order to race. The maximum heart rate is 220 (beats per minute?) minus age. For him, age 40, that means 180. For me, age 53 (almost), that means 167 (if my math is right).
Both for heart rate and for breathing, it is important to maintain different running paces in different training runs during the week. We are urged to do at least four runs, preferably five, with one being LSD--long slow distance. "Slow" means you can talk comfortably, breathing is not a big issue, and you really feel able to go about your farthest, or stretch the distance out a bit. At the other extreme is a tempo run, with or without speed runs, intervals, fartleks, etc. A tempo run is not 100% of what you can do, or a sprint, but it is 70% to 80% of that--it feels fast, you don't feel you can talk comfortably. A tempo run should be much shorter than your long slow run. In between is a steady run.
I'm doing four runs a week, and a couple of swims, with a swim on the weekend being long for me at 40 lengths. Our instructor said he has never trained by doing five runs a week--he has done four plus a cross-training session. I run with the group Tuesday and Wednesday evening. Tuesdays for the next while will be hills: don't really focus on speed, but on keeping the heart rate down, not over-doing it, moving the arms to maintain momentum, look forward not down, and being aggressive without really racing. Walk a bit on level ground, then do the downhill leaning forward slightly, small steps, let gravity do the work and take a break. Serious injuries are possible taking big steps downhill.
Wednesdays I guess will be tempo. Last week I made the mistake of going fairly quickly on the way back from our hill course. Wednesday I was feeling it, and lots of people doing a tempo run passed me. Thursday on my own I'll do steady, and then LSD on Saturday.
I don't own a heart rate monitor, but a Garmin with a lot of software may be in my future.