Mid-Range Progression Runs
Medium to long in length, these workouts are geared at boosting the aerobic system by adding an increased aerobic stimulus once the body starts to tire halfway through a run. Studies have shown when a runner increases aerobic resistance after they’ve become glycogen-depleted (in other words, start running low on fuel), the body produces considerably more aerobic enzymes, which in turn helps the body do a better job of processing lactate. The net result is that it allows you to run at a faster pace longer before you fatigue. The mid-range progression run helps prevent long runs from becoming tight, monotonous shuffles in which the stride length gets too short and neuromuscular timing goes flat.
When: Once a week.
How: Head out for a 12- to 14-mile run in which the second half of the run is completed at a moderate pace, or a longer run done mostly at an easy pace, but with the final 30 minutes at a moderate pace. Try some variation of a moderate progression run one or two days after harder workout days such as an interval session. If you’re not doing aerobic work after those harder days, you’re not going to strengthen your specific endurance for your goal race.