Choosing the right pace for you during the marathon is the key to how well you will eventually complete the race. First of all, it is important to understand what is happening to your body as you go through the long distance of the marathon.
You’ll be running quite comfortably at first (hopefully anyway !!), due to your marathon training and carbohydrate stores (glycogen stores). However, your supply of accessible “fuel” is limited, and as you hit the 17-mile mark and beyond, you need to draw energy from your body’s protein and fat to keep going. At the same time, you are also fighting dehydration. You can lose 2 to 3 pounds per hour of body weight as you sweat during your run.
Now imagine it is a windy day or a hilly course (or both!). Your energy output must increase if you want to maintain your target for pace and time. However, this may mean that you will deplete your available energy reserves before hitting the 17-18 mile mark.
The same goes for the level of temperature and humidity during the race. If these are high, you will sweat more and be more affected by dehydration. This will negatively affect your performance by 10-15%, which translates to approximately 1 minute per mile. In other words, it will slow down …
Marathon runners ‘hit the wall’ because their glycogen stores are depleted and they feel really weak. This feeling will be aggravated by the effects of dehydration. At this point, many runners have to stop and walk just to keep going. Obviously, they won’t be able to reach their marathon time goal.
So, knowing all this in advance, the smart marathoner will carefully assess the race conditions at the start of the race. If it’s hot, it’s best to start slower until you’ve reached a steady running pace. The same goes for the headwind. You also need to consider your running form after six miles or so. Are you relaxed and feeling as good as you should at this early point in the race? If not, it’s time to slow down for a while to see if it recovers.
To successfully complete a marathon, you must run as far as you can within your body’s comfort level. That may sound like an oxymoron when we talk about 26.2 miles, but it is possible! If you can hit the 16 mile mark without much stress, you have a good chance of finishing the race without too much trouble.
The key point is to start with a target pace range in mind, and not an absolute target like 3hr 45m. For example, you can choose a pace between 8:30 and 9:00 minutes per mile (for a marathon time in the range of approximately 3 hours 40 m to 4 hours). Then adjust your pace according to the conditions and your own ability to run on the day of the marathon. It’s generally best to start at the slower end and then increase your pace as you progress through the race.
Give this a try and you might be pleasantly surprised at how well you completed the race.