The "wave run" is a type of workout concocted by Tinman, the well-renowned running coach. It is used by many of the people he coaches or used to coach, including rbbmoose, Jim24315 and others. Lately a number of people here have adopted it, such as MCSolar, Gin, and over on RA biketm and a few others.
In the Tinman approach as I understand it, you do two quality workouts per week, not the usual three, but all your quality work is done within them. So you have one long run, and one medium-long run. The wave run is done in your long run, which differs in length based on what you are training to do. E.g, the marathon training program would have you going a bit longer. But for just getting into it, a typical wave run would be about 13 miles, and after your warm-up contains miles at HM or MP pace, followed by easy miles. Here is the one I used to use when I was healthy:
Mile 1: Slow, to warm up
Mile 2: Easy
Mile 3: Easy
Mile 4: MP
Mile 5: Easy
Mile 6: MP
Mile 7: Easy
Mile *: HMP
Mile 9: Easy
Mile 10: HMP
Mile 11: Easy
Mile 12: HMP
Mile 13: Slow or easy
This workout flies by in no time, because you are concentrating on the pace, and it is packed with quality. You get a nice long run in, and you get some mileage at a good pace, AND you get internal recovery time. I have given this run to several people and all of them rave about how effective it is. For your first one, you may wish to write it out and tape it to your arm, but it's easy after that.
(BTW, your medium long run would be about 9 miles or so, and include interval work, a tempo run or progression run.) Tinman's approach has extraordinary appeal for Masters runners because of the added recovery time you get in each week, which Masters runners require as they don't recover as fast as they did when young. Don't I know it! Spareribs