Marathon or Half Marathon?

Doing a full marathon shouldn't interfere with your HIM goal unless the HIM is within a month or so of the marathon. Are you planning on doing the marathon just to finish or are you planning to have a goal time? There is a big difference in the time and mileage needed depending on your plans. Realistically is you're going to have a successful race you can plan on bumping your running mileage to around 50 miles/week. That's a substantial increase from where you're at. You can finish a marathon on less mileage, but it won't be pretty and may leave you with a longer recovery.

FWIW, last year I did a marathon in early May and my first HIM in early June. The marathon recovery left me unable to do much run training in the time between the races making the HIM run much longer than I had planned. I think if the HIM had been at least 2 months after the marathon my HIM run would have been much better.

If you're targeting March, I think you're more than ready to run the full marathon. You have the rest of the year to build a strong base and then can shift to the 18 week training plan. I'm doing my 5th marathon this fall and I never hit the 50 miles/week that some people do. I've done two poorly trained, which I do not recommend at all, and trained with a peak of 40 miles over 4 days/week for the other two. I have had some injuries so less running days works better for me. I do a long ride to substitute the 5th day of running and now that I'm doing triathlon, it works even better since I don't have to neglect the other two sports. And with my running mileage currently increasing, I'm enjoying swimming even more as well.

It's a phenomenal experience and it sounds like you have the time to work toward it. Good luck with your decision and training! 

I think a lot of it depends upon how you know yourself, how you recover, what our goals would be for a half or full marathon, etc.  If you're looking to complete them or compete in them, then there would be a difference.  Depending upon the plan you do, there is definitely still plenty of time for swim and bike that actually assists your training for the run as cross-training for you.  I know marathon training for me positively impacted my next 3 months worth of events as I had such a solid base from it.  I am currently signed up for a HIM in early Oct. and a full marathon in mid-Nov, now my focus is the HIM, and I'm not looking to PR the Mary, but I know specifically for me, that by adding some longer running to my HIM plan is what is needed for me to do well at the HIM.  But that is because I know me and what I can handle and what helps me to better at different things.

Not to go much more, I would say that if you're looking at a March marathon now and Fall HIM, if you WANTED to do the Mary AND your body doesn't get destroyed by running long distance (totally individual) then you could balance both, still do swim and biking on your non-run days (non-impact, so long as they aren't crazy long you can maintain those bases, and then recover from the marathon and pick up with HIM training with plenty of time to do it properly.  So, it really is dependent upon what your goals are, what your body can handle, and what you WANT to do...me, I'd go for it, but that truly is just what I would do for me.

So set yourself an agressive goal for the half marathon.  That would still require more miles than you're currently doing, but without the need to really ramp those long runs for a marathon that will increase your risk of injury.

A marathon will force you to run more.  But for many people, it pushes them to run more than their body is properly prepared to handle.  And they end up with injuries and become convinced that they aren't 'meant' to be runners.  Not saying this WILL happen to you if you choose the marathon, but I've seen it with more than a handful of people.  If you do decide to do the marathon, I would start working on building your running mileage and frequency now so you can keep it as gradual as possible.

Folks,

First we need to clear one thing up. The original poster said she currently runs 50 miles per MONTH. I don't know if she meant 50 miles per week, but I will assume she meant what she said 50 miles per month. This translates into less than 12 miles per week. My opinion is that this is not enough for a full marathon. That being said I think it is possible to do a full marathon on 25 - 30 miles per week. The key would be to keep extending the long run by a mile or two every other week until you get to a long run of 20 miles.

If Jessica meant 50 miles per week is her current load than absolutely go do the full marathon.

chevy57    

You are talking about two different worlds. The only thing in common is that they are done just running

In general I would NOT suggest to anyone to do a full marathon.

The half marathon is a nice race but I would definetely prefer the 10k.

Now, about your question, why the HM instead of the full one. First of all, I assume that your goal is to make one or the other, taking out your best performance from your body. Otherwise, if you say that the goal is just for fun, you can just go there tomorrow and run/walk around the cut-off time, with the minimal effort.

Here are my considerations on the full marathon: 

1. Training time: unless you have a long experience in running, you need to build a good condition for that, with several long runs, IT and many miles per week, more than those you run at the moment.
2. Mental effort: as a consequence of (1), the mental effort during your preparation and during the race itself is much bigger on the full
3. Tapering and recovering: if you are doing some other sports, recovering especially can take some time off from other sports
4. Chance of failing: much higher on the full, leading to all the bad consequences
5. Chance of injury: quite high on the marathon, quite proportional to your BMI and to the miles volume/week

There is no benefit of doing a FULL marathon in general, even if you are going to do a full Ironman, where you can go straight there for your first marathon.

Now, a question for you: why are you considering the full marathon race and not a 10k race?

Understood on current mileage--and I'll still say that it's totally dependent upon personal goals and what the body can do, but she is looking at a marathon in March--that is 7 months away--ample time for someone to build up the mileage and train for a marathon without hurting herself--if she said a marathon this fall or Dec, I would totally say don't do it, you'll hurt yourself.  I really think that this comes down to personal preference/goals and knowing whether or not running long thrashes the OPs body.  If it's a goal to complete a marathon, and the OP wants to get some long running in for experience--then do it, they're fun (if you like that sort of thing).  But, just my two cents

Doing a long run of 20 miles when a person is only running 30 miles/week is a recipe for injury. 2/3rds of the weekly mileage would be that one run - way too much.

She would need to build her mileage from the 50 miles/month, but she has about 8 months and that should be more than enough time to ramp up.

I've seen plenty of people try to run their first marathon on 20-30 miles/week of training. These are the people who typically have a miserable time and take 5+ hours to complete the race. Some people are successful with minimal mileage, many are not.

Building to 50 miles/week is not that hard. All it takes is daily runs of 6-8 miles. Most people with decent fitness could ramp up to that within a couple months.

You should check first which was the goal of those people. Maybe it was "just to finish" and the goal was accomplished. Therefore the 5+ hours were not "miserable" 

That's what I was thinking.  I would only have to increase my distance by a little less than a mile per week (I do about 8mi. for my long runs each week).  That seems perfectly reasonable to me.  And that's easily within the 10% increase per week rule.  I have been fortunate enough to never have had any health issues (ie. knee problems) that would have kept me from running.  My only goals for the full would be to run the whole thing.  I'm the kind of person that needs to have a goal at the end or I slack.  I can't just work out just to work out.  Races keep me going.  And if I know I have to be prepared to run 26 miles in March, I will surely not be sitting around all winter.  And why not a 10k?  It's not enough.  I would love to build speed, but that comes in time.  A 10k wouldn't occupy me for long enough in training. 

 She has until the end of March to build a run base and adequately train for a marathon. Obviously if she wanted to run the marathon in 2 months or so it would be a bad idea. However, 8 months is more than enough time to build up to that distance. You have to start somewhere. I completely agree that she will need to run more than 50 miles per month, but again she has 8 months. 

During my training for this past ING I ran between 30 and 40 mpw and I did a 3:45..not miserable at all.

It would if you set your goal high enough and trained properly for it.  Training for a 10k, half marathon or marathon are not that different in tems of how much you SHOULD run.  Only in how much you NEED to run.

But good luck in whatever race you choose.

You can be very very occupied with a 10k race preparation. You should not think that preparing a 10k mean that you should run few miles per week.

Again, I think that you are looking to races "just to finish", this is my impression. Then, for sure, 10k, half marathon or whatever does not need any specific preparation. Just go there and run/walk until the end.

If you want to achieve a great result which is doable for you (the best out of you), then 5k, 10k, half marathon, etc. will require always good mileage and QUALITY trainings during the week.

In Italy, among runners, there is a famous "dead man walking test": 10K under 60minutes. That is a good starting point... 

Nope... I still have pulse. PHEW!