Although it seems rather counter-intuitive to me, I have heard multiple times that running just a single Marathon per season is more unhealthy than 3-4 Marathons per season.
The reasoning seems to be that it should be rather stressful to the body to get in shape for the first Marathon, but keeping fit between runs shouldn't so bad.
I have looked for some materials on the web to clarify the issue, but to no avail. Can anybody clarify the issue for me?
It would seem there are so many variables involved that are independent of the number of marathons you run to make any such conclusion meaningless.
For example:
Clearly for an ultra marathoner who has spent decades training, running one or three marathons a month even may not make a difference.
At the other extreme a newbie who is working towards their first marathon, should probably find three marathons in a season a really bad plan.
However in between is where the interesting bits happen.
There is value in keeping your base training for longer, and just using the marathons along the way as long training runs, perhaps at a faster pace.
I notice the question did not ask, Racing 3 marathons vs 1. I think that is a key distinction as well. If you race the marathons, then that is very different than just running them.
I suspect this is one of those 'it really depends' answers.
Last year I ran two ultras and four marathons, all quite slowly, all but one with negative splits, and it feels very good. I completed two marathons on two consecutive weekends, and enjoyed them both.
Before that, I was trying to improve my speed, running 1-2 races per year, and that definitely was less healthy for me. I did not like tapering - last week before the race just felt terrible. I hated the recovery - I'd rather work out than rest because of sore muscles.
So, for me trying to run one marathon per year with full effort was not healthy and not enjoyable at all. Running multiple ones with enjoyable speed, not hitting the wall ever, with negative splits, and no pain is a lot of fun. I am just staying in shape all the time, and enjoying a good scenic race whenever I feel like it.
We are all different. What works for me might not work for others. I am not cut out for fast running: I do not look like a lean gazelle. On the other hand, having considerable muscles and thick and strong tendons allows me to run injury-free, even though it prevents me from running fast.
I have lean friends who have real chances to qualify for Boston, (1-2 minutes short), but keep spending considerable time every year limping. They are much faster but more prone to injuries.
It's not actually running the marathons that's more healthy, it's staying in marathon shape for the whole time, as opposed to building up to a marathon, then letting yourself go for the rest of the season, then having to build up for the next marathon, etc. Building up is where you are most likely to injure yourself, so staying in shape between marathons is the important thing, not running more of them.
I don't think these long runs are a healthy or natural activity for the human body, so the fewer the better. If you are interested in health rather than marathon performance, mix up your exercise types, include high intensity and weight bearing activities as well.
