This challenge recruits both types of endurance-happy muscle fibers (slow oxidative and slow glycolytic) when each has already been significantly taxed but not exhausted, owing to the run's basic duration. The result is a training stimulus not available in either shorter or longer runs.
Pfitzinger cautions against going overboard with the fast-finish MLRs, even if you feel fantastic. There can be a fine line between incurring a level of fatigue that generates a considerable training stimulus without needing days of recovery and hammering yourself so strongly that the aftereffects are more race-like than training-like.
One lesson few endurance athletes fail to learn in their competitive lifetimes is that gauging how much more your legs can take when you're already 90-plus minutes into a run is very tricky, and it's best to not have to find that out the hard way.
As with the other types of MLRs, these can be accommodated once every three weeks or so.
Putting It All Together
Here is a sample MLR schedule for a 3:30 marathoner. Athletes who do their long runs on Sunday morning are advised to do their MLR on Tuesday afternoon or Wednesday morning, which allows for one additional intense session on Friday. In any event, a rest period of 60 to 72 hours between an athlete's longest two runs of the week is optimal.
Also, Pfitzinger recommends that more seasoned athletes incorporate MLRs done right off the bike. If you opt for this route, stick with doing this "brick" on days when your MLR doesn't include either tempo or fast-finish portions, at least in the beginning.
| Week | Distance | Specs |
| 1 | 10 | Last 2 miles in 14:10 (7:15, 6:55) |
| 2 | 11 | In 1:40:00 to 1:45:00 |
| 3 | 13 | Last 4 miles in 29:40 (7:25 pace) |
| 4 | 11 | Last 1.5 in 10:30 (7:05, 3:25) |
| 5 | 12 | In 1:48:00 to 1:53:00 |
| 6 | 14 | Last 5 miles in 37:00 (7:24 pace) |
The next column deals with interval training, thus concluding this three-part series on the various types of running workouts you'll want to consider regularly including in your pre-competitive-season training.