Most runners know the benefits of the long run when training for the marathon or half marathon distance. However, what most marathoners don’t realize that they don’t need to run for longer than 20 miles in their marathon training. Moreover, they don’t necessarily need multiple long runs over the 18-mile distance unless their goal is to finish under 3:30. While there is no doubt that a 21-mile run (or longer) can be a great confidence booster, from a training standpoint, they don’t make too much sense. Here’s why:

Most runners training for the marathon are averaging anywhere from 9 minutes to 12 minutes per mile on their long runs (3:45 to 5-hour finishing time). At a pace of 10 minutes per mile, a runner will take roughly 3-hours and 40-minutes to finish a 21-mile run. The total amount of time on your feet during a 3 plus hour run will break down the muscles and completely exhaust you, which leads to a significant delay in recovery time and means you can’t complete more marathon specific workouts throughout the following week, which I believe are a more important component to marathon success.

Furthermore, your body doesn’t see a significant increase in training benefits after running for 3-hours. The majority of physiological stimulus of long runs occurs between the 90 minute and 2:30 mark. To add insult to injury, running for longer than 3:30 significantly increases your chance of injury. Therefore, you’re leveraging some very slight training benefits for increased fatigue and injury risk.

Instead, it’s better to string out the workouts and mileage over the course of the week, which increases the total amount of quality running you can do along with decreasing the potential for injury. I recommend shortening your long run to the 16 to 18-mile range and buttressing it against a shorter, but steady paced run the day before. This will simulate the fatigue you’ll experience at the end of the race, but reduce your risk of injury and excess fatigue.

I also recommend this practice for the half marathon distance. By adding a steady run the day before the long run, you can simulate late race fatigue without having to run the full distance and teach your body how to finish strong and fast.

In addition, when you have shorter long runs, you’re able to increase the total quality and quantity of tempo and aerobic threshold workouts throughout your training week. Developing your aerobic threshold is the most important training adaptation to get faster at the marathon distance because it lowers the effort level required to run goal pace and teaches your body how to conserve fuel while running at marathon pace.

Finally, with a focus on shorter, more frequent long runs, you can implement faster training elements, such as fast finish long runs and surges, which allow you to increase the overall quality of your runs. These fast finish long runs and surges help you increase the pace of the overall run, get you familiar and adapted to running marathon pace while tired, and also increase your body’s ability to store and use fuel more efficiently.

When I first discuss this concept with many veteran marathon runners, or new runners who are getting advice from their marathon-seasoned friends, they always counter with what do the elite marathoners do for their long runs (males running under 2:18 and females under 2:30). While some runners do run over 22 miles, there are not as many as you might think, and it usually only occurs once in a training cycle. More importantly, elite male runners typically run their long runs at between 5:30 and 6 mins per mile on average. This means a 22-mile run might only take them a little over two hours. As we’ve discussed, it’s the 3-hour barrier that produces the significant increases in fatigue. While these sessions are tough for the elite runner, they typically recover fast (it helps that they devote their lives to running and have ample time to sleep, eat right, and get massages).

When you balance out the gains you can get from finishing a long run fast and upbeat with the negatives from an extended long run, you can see why a shorter, faster long run is the better training option for almost all marathoners aiming to finish over 3:30.

This is a somewhat controversial topic, so I welcome you comments, thoughts and questions.