How Fatigue Can Help You Run Faster
Running coaches use the term "accumulated fatigue," which means the effects of one workout will build up and transfer to your next training session. Because of this, whenever you start a run, you'll already feel slightly worn out from your previous workout.
Accumulated fatigue is especially important for long-distance training because it simulates the way a runner's body feels late in a race. Training while slightly fatigued can help a runner prepare for the specific demands of a half marathon or marathon.
Here's an example of how to use accumulated fatigue for marathon training. If you run 6 miles at marathon pace the day before your weekly long run, you'll start your long run feeling tired, and your glycogen stores will be depleted from your previous workout.
You can also apply this theory to 5K training. I often have athletes run a short, explosive hill workout (something like 9 x 60 second hills at 5K pace) two days before a 5K-specific workout (12 x 400 at 5K pace with 60 seconds of rest between intervals). The hill session exhausts the fast-twitch muscle fibers, then during the 5K-specific workout, these muscles (primarily responsible for running at 5K pace) are specifically targeted and forced to adapt to a greater workload.
More: How to Cheat Fatigue
How to Find the Right Balance
Training would be much easier if you could always run hard while fatigued, but you can't expect to do this as your training progresses. You need to find a balance between running and recovery.
First, try to only do specific workouts once every two weeks, and only schedule them during the race-specific portion of your training schedule. This reduces your risk of burnout and injury.
Be sure to keep your easy runs slow. One of the most common mistakes runners make is running too fast on their easy days. This hinders your ability to recover, and doesn't provide any additional aerobic benefits.
Research has shown that the most optimal aerobic pace for an easy run is about 65 percent of your 5K pace. For a 20-minute 5K runner (6:25 pace for a 5K or 7:20 pace for a marathon), this would mean about 8:40 per mile on easy days.
Finally, make sure to take a rest week every 5 to 6 weeks, where you reduce your intensity and mileage by 65 to 75 percent. Rest weeks allow you to recover from your workouts and help you manage fatigue so you can use it to your benefit during training.
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