The last of the main types of faster running are also known as rhythm runs or marathon-pace runs. The latter name tells you what you need to know about the desired effort level—the fastest pace you could sustain for two to three hours (yes, even if your marathon time is slower than that). These efforts combine some of the benefits of shorter tempo runs with those of long, easy runs. The result is overall improved aerobic strength, in part because of your leg muscles becoming better equipped to receive and make use of the oxygen in your blood.
Long tempo runs can last from 40 to 80 minutes, or 6 to 10 miles if you’re thinking in terms of distance. They’re typically done as the second part of an otherwise regular long run. But you can also make them their own entity on other days, sandwiching them with a warm-up and cool-down just like you would other types of hard workouts.