Pfitzinger Pete - Advanced Marathoning

Improving Your O 2 max

The most effective running intensity to improve O 2max is 95 to 100 percent of current O 2max (Daniels 2005). Well-trained runners can run at O 2max pace for about 8 minutes. Ninety-five to 100 percent of O 2max coincides with current 3,000-meter to 5,000-meter race pace. This coincides with an intensity of approximately 94 to 98 percent of maximal heart rate or 92 to 98 percent of heart rate reserve. Running intervals at this pace or intensity is part of the optimal strategy to improve O 2max.

The stimulus to improve O 2max is provided by the amount of time you accumulate during a workout in the optimal-intensity range. This fact has implications for how best to structure your O 2max sessions. Consider two workouts that each include 6,000 meters of intervals – one of 15 × 400 meters and the other of 5 × 1,200 meters. When you run 400-meter repetitions, you’re in the optimal zone for perhaps 45 seconds per interval. If you do 15 repetitions, you would accumulate about 11 minutes at the optimal intensity. When you run longer intervals, you are in the optimal-intensity zone much longer. During each 1,200-meter interval, you would be in the optimal-intensity zone for 3 to 4 minutes and would accumulate 15 to 20 minutes in that zone during the workout. This would provide a stronger stimulus to improve your O 2max.

The optimal duration for O 2max intervals for marathoners is approximately 2 to 6 minutes. Intervals in this range are long enough so you accumulate a substantial amount of time at 95 to 100 percent of O 2max during each interval but short enough so you can maintain the optimal-intensity range throughout the workout. Intervals for marathoners should generally be between 800 and 1,600 meters. The training schedules in this book include some workouts of 600-meter repeats during weeks when your top priority lies elsewhere, such as when the week also calls for a tune-up race.

The training schedules don’t include 2,000-meter repeats. Although repeats of this length can provide a powerful boost to O 2max, for all but the elite they take more than 6 minutes to complete. That’s fine if you’re focusing on a 5K or 10K, where O 2max is the primary determinant of success. As a marathoner, though, you want to be fresh for the week’s more-important endurance workouts, so you don’t want your O 2max workouts to require several recovery days before and after.

The total volume of the intervals in a marathoner ’s O 2max session should be 5,000 to 10,000 meters, with most workouts in the range of 6,000 to 8,000 meters. Any combination of repetitions of 800 to 1,600 meters will provide an excellent workout. Longer intervals (e.g., 1,200s or 1,600s) make for a tougher workout, physically and psychologically, and shouldn’t be avoided.

The optimal amount of rest between intervals is debatable. One school of thought is to minimize rest so that your metabolic rate stays high during the entire workout. This strategy makes for very difficult workouts (which can be good), but you risk shortening your workouts. Another school of thought is to allow your heart rate to decrease to 70 percent of your maximal heart rate or 60 percent of your heart rate reserve during your recovery between intervals.

For the lower-tech crowd, a good rule of thumb is to allow 50 to 90 percent of the length of time it takes to do the interval for your recovery. For example, if you’re running 1,000-meter repeats in 3:20, you would run slowly for 1:40 to 3 minutes between intervals.

The O 2max sessions in these schedules feature repeats that strike a balance between being long enough to provide a powerful training stimulus and short enough to leave you fresh for your other important workouts of the week. Because O max training is not the highest priority during marathon preparation, the O 2max intervals in the training schedules in chapters 8 through 12 are run at 5,000-meter race pace. This coincides with the lower end of the optimal heart rate range, approximately 93 to 95 percent of maximal heart rate or 91 to 96 percent of heart rate reserve for most marathoners. Running your O 2max intervals in this intensity range reduces the recovery time required before your next hard workout. (Be sure to use an accurate assessment of your current 5K pace, namely, a race run under optimal conditions, not a hilly course on a hot day.)

Don’t Max Out Your O 2 max Workouts

Two related mistakes that marathoners sometimes make in training are running intervals too fast and running intervals too frequently. Let’s consider why you should avoid these errors.

A common mistake among marathoners is to do speed work too hard. The idea that running your intervals harder will make you run better is appealing, and it seems logical. It’s also incorrect. Running your intervals faster than the optimal zone will do two things – build up a high degree of lactate in your muscles and shorten the duration of your workout. Both of these effects are counterproductive for marathoners.

The marathon is an aerobic event. More than 99 percent of the energy you use in the marathon is supplied by your aerobic system. As you saw earlier in this chapter, during the marathon, you run slightly below your lactate-threshold pace; therefore, you don’t accumulate much lactate in your muscles and blood. In fact, when lactate levels are measured at the end of a marathon, they are only slightly above resting levels.

There’s no reason, then, for marathoners to do training that builds up high levels of lactate, such as intervals run at 1,500-meter race pace or faster. Running intervals at this pace produces high levels of lactate and improves your ability to produce energy using the glycolytic system (what you probably think of as running anaerobically) and to buffer high levels of lactate. None of these adaptations is relevant to the marathon. Running intervals much faster than 3,000- to 5,000-meter race pace also produces a smaller stimulus to improve your O 2max.