There is a lot of debate about whether or not runners should include a run up to 20 miles in their marathon training. Some plans call for no 20 milers, some call for multiple. Some coaches and runners believe a 20 miler is too much while others swear by them. After training for the marathon, I can see both sides of the argument.
If you’re an experienced runner squeezing in 70-80 miles a week then a 20 miler probably isn’t even necessary. At the other end of the spectrum, if you’re a less experienced runner running lower mileage and find that the longer distance weekend runs in the training plan are resulting in the need for extra recovery time (and therefore, missed weekday runs), then the 20 miler probably isn’t very beneficial. If you’ve run multiple marathons, then you may be fine with just running 16-18 miles having completed enough marathons to know you can do it.
Then there’s those of us in the middle. I wasn’t running high mileage, but I also didn’t need extra recovery after my 20 and 22 milers. Maybe I didn’t need the 20 or 22 miler to successfully run the marathon, but I saw a lot of benefits from it. First there was the ever-famous “time on your feet” which I found to be mentally helpful and probably more so than physically helpful. Because my 22 miler was done at a slow, easy pace I only ran for about 7 minutes longer on marathon day than I did for my last long run. Going into the race, I knew my body was capable of staying strong for a long duration of time.
Another benefit was being able to really practice fueling. I had never taken more than two gels on a run and the 20 and 22 milers were my opportunity. I knew I could handle two, but what if 3 was too much for my stomach? What if I needed to take one sooner than every 5 miles? There’s no perfect formula and anything can happen on race day, but going into it knowing I had success with fueling on my training runs is always a good place to be.
A final benefit for me was the opportunity to test out my race day shoes. This may sound silly, but it really was the decision maker for me. After my 20 miler, my feet and legs felt pretty good. After my 22 miler, my calves were tight and sore in a way they hadn’t felt previously and I couldn’t imagine an extra 2 miles did me in. I decided to wear the heavier, more cushioned shoes I wore on my 20 miler instead of the shoes I usually wear for half marathons that I wore on the 22 miler. Had it been a cooler either day, it could’ve been a good opportunity to test out my race day wear as well.
I don’t think there’s a right or wrong when it comes to choosing whether or not a runner will include a 20 miler or not. For me personally, a 20 or 22 miler is something I would definitely include in my next marathon training cycle.