You usually hear that negative splits are the way to go. Run the second half of the race faster than the first half of the race. It's said to be a good strategy when competing with others for a victory, and is the favored strategy for athlete's vying for the top spot on the podium. But seriously... negative splits are not for me - at least not at my current level of fitness.
There's a big difference between being at or near racing fitness, like someone who has been training for years or like an elite, and being just a serious runner. I'm sort of the latter. I have a lot of training to do before I am able to run some truly fast times for my age. For now, I am relatively fast and having been training for less than two years, I can only be considered moderately trained as a runner, at best.
Many people who are moderately trained or even those who are trained only well enough to basically complete the races they enter, often lament that they can't manage negative splits or that they even struggled to maintain a steady pace over in the events they enter. Sure, some of this is the excitement of the race which leads to fast starts, but many of us also find that even when we can hold back a little in the first half, we still don't have enough gas in the second half to ramp up and achieve a personal best. We look back after races and say, I should have run harder in the first half, or I should have started my move earlier toward the end...
We make mistakes in strategy that are partly volitional and partly due to our physiological limitations. We hold back too long before picking up the pace near the end or we go out too fast (volitional), or we start out a little slower than goal average pace, and then just don't have enough left to pick the pace up in the second half of the race, anyway (physiological limitation). We lack the experience to know more reliably how to pace ourselves strategically, and we lack the level of conditioning required to vary our pace to run negative splits.
So, I don't worry about negative splits. I go out and just try to settle into a pace that feels hard, but like I can maintain it if I have to. The two times I have tried to hold back in a race to use some strategy (5K distance), I was still unable to muster the kind of effort needed to bring my average pace down to my goal. When I have just run as fast as I felt I could manage, however, I've most often had positive splits, or something relatively even, and finished with something close to my goal time or a new PR.
Part of the issue is that I'm not competing against any specific "other" runner. I'm just trying to run "my" best race. I'm trying to beat my previous best time in an all-out effort with a new all-out effort. If I was so conditioned that further improvement and PR's had become less frequent, and amy goals were to beat some other runner to come in first, rather than always to improve on a my record, negative splits might make a little more sense, because directly racing another is partly psychological.
Indeed, some research has recently been published that suggests novice and moderately trained runners (like most of those in citizen races), might achieve their best times by going out a bit faster than their average goal pace (at least at the 5K distance used in the study).
Elite runners, who have the experience and condition needed to better judge how to pace themselves for peak performance may do better with a negative split approach, but most of the rest of us should probably just go out and run!