The longer you have been running the easier it will be to pace yourself during a race. However, even the most experienced runners have trouble pacing when it comes to marathon distance. It's been noted that about 90% of marathon runners complete the second half of the race in a slower time than the first. Ideally, the goal is to run at an even pace throughout the entire race.
The subconscious mind is believed to control pacing. It's mission is to protect you from YOU! In other words, it determines the pace at which you can maintain over the course of 26.2 miles without endangering your life. The more experience you have, the more you can believe your subconscious.
If pacing is off, it could result in muscle cramps, the infamous "BONK", a loss in good form resulting in injury. To top it all off, you won't meet your goal finish time. In the early miles, it's absolutely mandatory to run at a pace that almost feels too slow. The pace should vary about 10 seconds from start to finish. One way to achieve this if you question your pacing ability is to look for pacing teams which will hold pace and get you to the finish within 2 minutes of your time.
If you want to go it alone, the easiest way to pace yourself is by looking at your last race time. The 10K race is a pretty good predictor. This is dependent on whether or not you have trained in the most efficient manner for your body. By efficient I mean the correct weekly mileage, enough long runs, sufficient speed sessions without incurring injury and overuse problems,e.g. misalignment's, stress fractures. You need to train hard for a marathon but not so hard that you end up injured and can't run at all. Pay attention to your body and what it's telling you during your training and your racing.
According to Active, run the first half by time and the last half by feel. Another advantage to achieving correct pace is to know the course. Going up hills will require more effort and you will slow, then going down, your pace will quicken but don't force it. Let gravity take you on the decline.
I gage my pacing as follows: long training run about a minute and a half slower than 5K pace.
Marathon pace should be about one minute or so slower than 5K pace. One last tip: don't expect to run training runs as fast as you run races. You'll be rested and the adrenaline will be flowing. Let the excitement of the day and all your training get you over that line. Good Luck!
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