There are a few workouts or races every year when everything is going well…until the end. Within 100 yards or so, you shift from feeling strong and under control to questioning whether you are going to finish. You’ve hit the wall: there’s no bounce in the muscles, energy level drops, and your breathing rate increases. You find yourself struggling even when the pace slows down dramatically.
Through training, you can avoid having to deal with the wall. Longer long runs and speed sessions, as noted below, will extend endurance even at a faster pace than you have run before. Your muscles have a higher workload, pushing you past the finish line.
Conservative pacing will save resources until the end—when you need them most. Whatever you save by going slowly in the beginning will be available to you at the end. But if you push too hard in the beginning, you will usually receive a penalty at the end as you slow down.
Walk breaks from the beginning can keep the pace on track and bestow strength at the end. See my books (5K/10K, Half Marathon, Galloway Training Programs) for instruction and current run-walk-run ™ ratios. Marathoners, for example, run an average of 13 minutes faster, in surveys, when they shift from running continuously to using the run-walk-run ™ method.
For best results, the length of the long run should be longer than the distance of the race. After analyzing the results of my e-coach and Tahoe retreat clients, I’ve found that diminishing returns set in for a marathon at 29 miles, in the half marathon at 19 miles (17mi for the 10K and 12mi for the 5K). This means that I continue to see time improvement among those who increase the length of the long run as noted—even when other training elements remain the same. The long ones must be done slowly: 3-4 min/mi slower than you are currently running in the race for which you’re training (2-3 min/mi slower than marathon pace).
Increasing the number of speed repetitions can allow time goal runners to maintain a hard pace longer in the race. This pushes back your anaerobic threshold, so that you will train yourself to deal with the accumulation of waste products, without slowing down. For the marathon I’ve had best success with mile repetitions (maximum of 14). For the half marathon, 800 meter "reps" (max of 14). Time goal runners in the 5K and 10K usually do best with 400 meter repeats (max of 14 for 5K, and max of 22 for 10K). The training programs for these events are detailed in the books (5K/10K, Half Marathon, Galloway Training Programs).
The "magic mile" (mentioned in my books 5K/10K, Half Marathon, Galloway Training Programs) can accurately predict what you’re capable of doing under ideal conditions at a very hard effort. By using an evaluation tool like this you can know what is realistic and make adjustments for hills, heat and crowded conditions. In very crowded races you may run between 50 and 100 extra yards per mile—which will slow your pace by 10-30 seconds per mile.
Pacing can either set you up for a good race or for a severe slowdown at the end. Most of the runners I’ve e-coached have run their fastest times with a "negative split" pacing strategy. This means starting at a pace that is slower than you are currently ready to run for the first half, which results in a faster finish time overall.
So there are a lot of things you can do to gain control over your running, and avoid the dreaded "wall".