Marathon running is an endurance event. Training to run 26.2 miles requires putting in enough hours of running for your body to be ready to handle the entire marathon distance. Training for long-distance running mostly uses your slow-twitch muscles and consists of running long distances so your muscles learn and adapt to running for long periods of time. However, for runners who have completed one or more marathons already, speed training does have its place in marathon training. According to Marathon Training, "Your arm drive, stride, speed and stamina will all improve as a result of infusing carefully designed speed workouts into your training. Together, these will enable you to run faster with less effort during your daily training runs," and faster training runs can translate into running a faster, more comfortable marathon.
A pace workout is designed to help your body learn to run at your marathon goal pace or slightly faster. It is not an all-out effort. In a pace workout, part or parts of a longer run are run at your goal pace. For example, a 50-minute run could be broken up into 10-minute segments. The first 10 minutes and the last 10 minutes are a warm-up and cool-down. During the middle section would be 10 minutes at goal pace, 10 minutes easy and another 10 minutes at goal pace. Pace workouts are easily adjustable to your fitness level and goals.
According to Hal Higdon, author of "Marathon: The Ultimate Training Guide," long repeats (800 m, 1600 m or even longer) generally work better than short repeats (200 m or 400 m) when training for a marathon. Hal Higdon suggests incorporating 800 m repeats into marathon training. The 800s should be run faster than marathon goal pace but not an all-out sprint. Each hard 800 should be followed by walking or jogging an easy 800. Start with four 800 repeats and work up to eight.
A tempo run is a run with no breaks that builds up to almost 10K race pace. Coach Jack Daniels defines a tempo pace as "one that you could sustain for about an hour--faster than your usual easy pace, a little slower than your 10K pace." A 40-minute tempo run would begin with 10 minutes of easy running and would build to the fastest pace in the next 20 minutes. The buildup portion should be gradual, with peak speed for only a few minutes. End the workout with a 10-minute cool-down of easy running.