Essential Efforts to Elevate Endurance, Part 1
Long Runs: Why and how to run them
By Pete Pfitzinger, M.S.
As featured in the September 2003 issue of Running Times Magazine
One of the questions I get asked most frequently is, "How fast should I do my long runs?" In the past, my standard recommendation has been to run 10 to 20 percent slower than goal marathon race pace. Upon reflection, this advice is too simple. The correct answer is, "It depends on how that particular run fits into your overall training schedule." In this column, we will briefly discuss the physiological benefits of long runs. Then, we will look at how hard to do your long runs to prepare optimally for a marathon.
Why run long?
Long runs stimulate a variety of physiological adaptations, which lead to improved marathon performance. One of the most important objectives of long runs is to deplete your glycogen (the storage form of carbohydrate) stores, which signals your muscles and liver to store more glycogen. Long runs also train your muscles to rely more on fat and less on carbohydrate at a given pace so your glycogen stores last longer. In addition, long runs play an important role in building confidence for the marathon.
What is the optimal intensity for long runs?
The appropriate intensity for your long runs varies depending on the objective of each training session. Some of your long runs should be truly challenging, while others should be downright comfortable. How hard you should do a specific long run depends on the amount of time until your goal race, and the effort required for the other workouts in your training program. The following four long run intensities all have a place in your marathon preparation:
1) 10 to 20 Percent Slower than Marathon Race Pace: This is the optimal effort for most long runs. The first few miles can be nice and easy, but by five miles into your long run, your pace should be no more than 20 percent slower than marathon race pace (MRP). Then gradually increase your pace until you are running approximately 10 percent slower than MRP during the last four to eight miles.
Because the faster you run the more glycogen you burn, doing your long runs relatively quickly is a more effective way to deplete your glycogen stores (and hence stimulate the muscles to store more) than running slowly. Similarly, if you jog your long runs your body will adapt to burn fat at a very slow pace but will not necessarily be trained to increase the proportion of fat utilized at speeds approaching race pace. Running at 10 to 20 percent slower than MRP is hard enough that you will also use a similar posture and running style as during the marathon, whereas slower long runs reinforce sloppy running technique. Long runs in this intensity range are difficult enough that you should schedule one recovery day before and one or two afterwards.