Hi, sorry this is a bit long winded but its from the Hal Higdon website and gives you a bit of an insight into running definitions.
Easy Runs: The runs on Mondays, Wednesdays and sometimes Fridays or Saturdays are designed to be done at a comfortable pace. Don't worry about how fast you run these workouts. Run easy! If you're training with a friend, the two of you should be able to hold a conversation. If you can't do that, you're running too fast. (For those wearing heart rate monitors, your target zone should be between 65 and 75 percent of your maximum pulse rate.)
Stretch & Strength: Mondays and Wednesdays are also days on which I advise you to spend extra time stretching--and do some strength training too. These are actually "easy" days, so don't overdo it. It's wise to stretch every day, particularly after you finish your run, but spend more time stretching on Mondays and Wednesdays. And don't forget to stretch while warming up for your hard runs. I can't emphasize this strongly enough: Advanced runners need to spend more time stretching than novice or intermediate runners! That's because you probably run faster and train harder, which can stiffen the body. And don't forget at least some strength training, which could consist of push-ups, pull-ups, use of free weights or working out with various machines at a health club. Runners generally benefit if they combine light weights with a high number of repetitions, rather than pumping very heavy iron.
Distance: The training schedule dictates workouts at distances, from 3 miles to two hours, the latter which (depending on your ability) may actually take you further than your half marathon race distance. Don't worry about running precise distances, but you should come close. Pick a course through the neighborhood, or in some scenic area where you think you might enjoy running. Then measure the course either by car or bicycle or a GPS watch. As an advanced runner, you probably already know the distances of many of your courses. When the prescribed workout (as on Sundays) is in hours rather than miles, forget distance entirely.
Rest: Rest is as important a part of your training as the runs. You will be able to run the long runs on the weekend better--and limit your risk of injury--if you program some easy training before and after. Be realistic about your fatigue level--particularly in the closing weeks of the program--and don't be afraid to take a day off.
Hills: Some hill training will help strengthen your quads and build speed. Look for a hill between 200 and 400 meters long. Jog or walk an equal distance between each repeat. I prescribed only three hill sessions, all in the first half of the program, but if you want to do more hill training, be my guest. You can substitute hill repeats for any of the interval workouts, or even in place of a Tempo Run or two if you want.
Speedwork: If you want to race at a fast pace, you need to train at a fast pace several days a week. The training schedule begins with 400-meter repeats, but also includes 800- and 1600-meter repeats in later weeks. Walk or jog between each repeat. You can do the 400 and 800 repeats on a track, although you may want to do the 1600 (mile) repeats on the road. For more information on speed training, see my book, Run Fast.
Warm-up: Warming up is important, not only before the race itself, but before your speed workouts above and pace workouts below. Most Novice runners do not warm up, except in the race itself. This is okay, because they're more interested in finishing rather than finishing fast. You have a different goal, otherwise you wouldn't be using the Advanced program, so warm up before you run fast. My usual warm-up is to jog a mile or two, sit down and stretch for 5-10 minutes
