I encourage you to consider running a 5k in your first two months of half- or full-marathon training. I found an organization called Park Run (https://www.parkrun.us/) that does local free 5ks throughout the year.
First, running a 5k can be a nice change from the normal routine of weekend long runs, which your body and mind will greatly appreciate! If you do most, or all of your training alone, a 5k will be a great opportunity to be around and connect with other runners. In addition, being in a race environment can be motivating and inspiring and help you enjoy and appreciate your training more.
Also, a 5k early on in your training can be a great way to determine your baseline fitness. Your performance from your 5k race can be used to predict your performance in a future half- or full-marathon, depending on your training for the next 12-16 weeks. This training will need to include long runs and other workouts that appropriately stress your aerobic system, such as progression and threshold runs.
Your pace for a 5k can be used to determine paces for your training runs by using prediction calculators. I use races and prediction calculators with almost all of the runners I coach, to tailor their workouts, so they are getting the most benefit, while training at paces that are most appropriate for them.
There are several online calculators that can be used including:
However, you need to use these intelligently in predicting your future half- or full-marathon pace. This includes taking 5-10 seconds off your 5k time and then plugging into the predictor calculator. Keep in mind this is a projected pace for these events, and certainly not a pace you would run these events at now. After all, you won’t have done long runs much more than 8-12 miles at this point.
You should aim for a negative split in your 5k. That is to run the last half of the 5k faster than the first half. The easiest way to accomplish this is to keep a consistent pace for the first three miles and then speed up for the last 200 meters or tenth of a mile. Also, Coach Jay Johnson, in his book Simple Marathon Training, recommends running the first mile very conservatively, including running the first half mile at a pace that is challenging, but comfortable. He says don’t worry about those people who pass you because most of them will be running a positive split (slower second half of the 5k). He suggests a negative split race is a better predictor of your aerobic fitness than a positive split race.
Make sure you recovery well from your 5k. You should perform a cooldown after the 5k, including walking and then stretching/foam rolling. Also, I recommend a brisk walk or other low to moderate cross-training the next day for approximately 30 minutes. You may want to take the following day off from running completely before resuming your running.
So, go out and enjoy a 5k!
Please let me know if you have any questions, or if I can be of help in any way.
Your friend and coach,
- Simple Marathon Training, Jay Johnson.