In the BC Endurance training system, we end all workouts at the first sign of fatigue. Fatigue contracts capacity for exertion. Workouts should have the opposite, expansive effect. So, it doesn’t make sense to run into significant fatigue during training.
The usual rationale for training into fatigue is to prepare the mind and body to race fatigued. But this rationale confuses fatigue with the discomfort deliberately induced by endurance training. You don’t have to be fatigued to train uncomfortably. All that’s needed is to run long enough to raise exertion to the uncomfortable level.
Think about it this way: we warm up to expand our capacity for exertion. Even after the “warm-up,” capacity can continue to expand (or at least plateau) well into a workout. This can show up with, say, slightly faster intervals at the same heart rate. Fatigue manifests in reverse when the pace slows at the same heart rate, or heart rate rises at the same pace. Fatigue has the opposite effect of warming up.
Of course, you may have to run into significant fatigue during a long-distance race. But a race is different from a workout. Workouts build ability; races prove ability. Workouts are difficult or less-than difficult; races are usually very difficult or all-out. Workouts are non-competitive; races are generally competitive. Workouts are run with less-than-best energy; races are run feeling eager, which is as good as energy gets. Workouts end with the onset of fatigue; races end when you cross the finish line.
Let’s be clear: a “good” workout expands capacity and ends at the first sign of fatigue. A good workout enables you to recover adequate energy in time for the next scheduled workout. Running into fatigue makes the workout harder and thereby lengthens the time needed for adequate recovery. Fatigue also raises the risk of injury. Thus, fatigue should be avoided at all costs. If this is true, how can we recognize the onset of fatigue beyond its many subjective aspects, such as heavy legs, deteriorating form, or the prospect of being burdened by the effort instead of being at least satisfied?
“A ‘good’ workout expands capacity and ends at the first sign of fatigue. A good workout enables you to recover adequate energy in time for the next scheduled workout.”
Again, the answer is tied up with your heart rate in relation to your performance. Someday, an enterprising entrepreneur will figure out how to use a heart rate/GPS monitor to calculate an objective measure of capacity in real time, because changes in capacity are the key to distinguishing expansion from contraction. If you’re that tech-savvy person, here’s how to set up the algorithm so you can make a million bucks.
You’re looking for a way to measure your capacity in yards (or meters) per heartbeat. If you divide the number of yards in a mile (1760) by the average number of times your heart beats per mile (which is your average mile pace multiplied by your average heart rate during the mile), you’ll have a measure of your proficiency. As you adapt to a workout, your proficiency will increase, indicating you can run farther with each heartbeat. Similarly, as you become fatigued, proficiency decreases.
There you have it: a full-proof way to run good workouts by recognizing fatigue every time! And a way to make effective use of high-tech instrumentation in real time.