If you have a good marathon training plan, this should not be a problem because your program should clearly specify how much long run you should be running per week in marathon training. For advanced runners, this should be basic, but if you are new to running marathon, you should not feel bad, everyone starts somewhere. It is important to understand that the one main cause of most injuries related to marathon training is overtraining. Until you understand how to avoid overtraining, you may never train to your potential. This is obviously because every time you start training you are forced to stop or quit by an injury. However, if you or your coach design a reliable marathon training plan and follow to the later, you will be far much better than most marathon runners.
So, coming back to the question, “how much long run volume per week is ideal?” The answer is it all depends on several factors such as your current total mileage per week, your marathon training plan, the phase of training, and projected date of competition among other factors. However, as a rule of thumb, your long run should be once per week and should not exceed 25 percent of your weekly mileage. For example if your current weekly mileage is 60 miles, then your long run should not exceed 15 miles.
It is important that you keep your long run easier than the shorter runs that you do. Running them too fast will not give you the benefits you should be getting from your long run. Remember every part of your marathon training plan is important for success and should not be changed unless the program or coach advises so. When doing long runs, it is also important to run them on trails or softer surfaces to avoid injuries that are associated with pounding on hard or paved surfaces. The fact that most marathon races are run on paved roads does not necessarily mean you have to do your marathon training on hard surfaces. It is fine to do some of the shorter runs on paved roads, but try to limit them to less than 25 percent of your weekly total mileage.
For beginner marathon runners, a good way to determine your long run pace if your marathon training plan does not specify is through your breathing. If you are struggling to breathe, you are probably running your long run too fast. Some other runners prefer to judge their pace based on easy or hard it is for them to hold a conversation during the run. A good long run pace in marathon training should allow you to hold a conversation as you run, not that you have to. Obviously, this will not help if you are running alone, in which case you can use your breathing.
Finally, it is invaluable to start your marathon training with a reliable marathon training plan or program. When you do so, you will limit the chances of encountering overtraining problems and put yourself in a better position to achieve your marathon training goals.
