@Syrinx, just a side note; I am a distance runner and coach a number of runners in two different clubs, and I've found electronic aids for pacing can, as often as not, be detrimental when it comes to training and racing. I have always wondered why those of us who don't used these aids seem to consistently out perform (on a relative basis) those who use them, especially in races.
My question was at least partially answered by a study I read last year which came to the conclusion well trained runners will naturally run their correct pace for their conditioning, current energy levels, the weather, the course, and the distance; the pace adjustments are subconscious, and more often than not, are dead on accurate. The flip side is those who rely on an aid for pacing can, and often do either run too slowly for any given workout/race, or worse, run too quickly in the early stages and burn themselves out.
As an example, I got back into running at 57 years old following a 13 year hiatus due to a badly broken leg; after some five months of training I got roped into running a very hilly 10-mile race. My goal pace prior to running my first race in over a decade was 9:00 per mile, and had I relied on an aid, I would probably have stuck with that pace until it was way too late. In the end I finished the course in 1:24, fully six minutes faster than I would have run.
Another example, one of the runners I coach had run a handful of 10K races and was lined up to run her first half marathon; her goal pace was 9:30; she stuck with that pace and ended up bonking at about the eight mile mark. After the race she told me by the three mile mark she was becoming concerned the 9:30 pace was too fast for the conditions, and by five miles she knew she was in trouble. Even still, she stuck with the 9:30 "plan" until she bonked.
