Since the days of legendary coach Arthur Lydiard, the long run has been the cornerstone of every runner’s program. While most runners, coaches and scientists don’t debate the concept of doing a long run, there is continual debate when it comes to the details. How long should it be? How fast? Is distance more important than duration? Should I rest before it?

Description
While the distance or duration of your long run will vary depending on your event, most experts agree that it should comprise 15-35% of your weekly mileage (For beginning marathoners it may be as high as 50%.) and be completed once every 7-14 days. There is also agreement that the effort of the long run should be relatively easy with heart rates between 65 and 75% of HRmax for the bulk of the run, possibly drifting to around 80% as your body becomes dehydrated, overheated and fatigued. For most runners, this intensity corresponds to a pace which is 45 seconds to 3 minutes slower than marathon race pace.

Benefits
The primary benefits of a long run involve how efficient you are at producing energy aerobically. There is an increase in the energy factories (mitochondria) of the muscles, as well as the enzymes that allow the mitochondria to process more fuel for energy. You also add more more oxygen-carrying blood vessels. As a result, your muscles use more fat as fuel, thereby sparing your limited carbohydrates reserves. Long runs also stimulate your muscles to store more carbohydrates. Over the course of your training program, your ability to store more carbohydrates and burn more fat is a key factor in allowing you to increase your long run length, total weekly mileage and intensity of workouts.

You’ll also find that your musculoskeletal system becomes more resistant to injury, and your mental toughness will increase as you learn to tolerate prolonged discomfort and fatigue. Long runs also provide the fitness base supporting all your hard workouts and races.

Caveats
Runners and coaches have varying opinions about several aspects of the long run. First, the distance will vary depending on your goal race. Table 1 offers general guidelines for your long runs based on your race distance. You’ll need to take into account your strengths and weaknesses as well as your available training time. For example, if you fall apart near the end of the marathon, you may want to build your long run to the higher end of the recommended range, whereas if you feel the long run is especially taxing on your mind and body, but don’t feel that your endurance is a limiting factor in your performance, you may want to stay on the lower end of the range.

The pace of the long run is also an area of debate. Some runners are content to plod along while others run their long runs relatively close to their actual marathon race pace. Both intensities have their place. We recommend that when extending the duration or distance of your long run you do them slowly. After you have run 2-4 long runs at a given distance, however, you can begin to gradually increase the pace up to 30-45 seconds per mile slower than marathon pace. One technique proposed by two-time Olympian Pete Pfitzinger in his new book, Road Racing for Serious Runners, is to begin the long run at a slow pace and gradually increase it to where the last 15-30 minutes are run only 30-45 seconds per mile slower than your marathon race pace.

There is also debate about whether you should rest up before a long run by taking an easy or off day prior or whether you should go into the run fatigued so that you’ll get even more benefit from it.

We recommend that when you are building to new distances or durations (particularly over 2 hours) that you go into the long run well rested. For durations or distances with which you have recent experience, you can begin them without being fully recovered from the previous few days of training. For this reason, we recommend that you alternate a long run of farther distance or duration with one of shorter duration (i.e, run your longest run of 2 hours on one weekend, then a shorter but faster 1.5-hour long run the next weekend).

Conclusion
For most runners, a long run once every 7-14 days is one of the most important factors in continued running success. With adequate nutrition; hydration before, during and after the run; stretching; massage and rest, you will find yourself reaching new levels of endurance — so get out there and go long.