Marathon training with high-ish distance, low instensity

Question

I've been cycling to work the last 2 years, and now I decided I wanted to switch it up and mostly run it. It's 7km (~4 miles I guess), so twice a day 5 days a week pretty much. Gives me ~70km per week. I've been doing it 2-3 weeks now, goes well.

I ran marathons before - like 3 or 4, usually every 2nd year or so. Haven't done any for about 4 years now and I'm missing it. I've always been between 4-5 hours because although I was very active and I did track & fields before and have always been running say once a week or so, I never really trained for a marathon. I'm 34.

Because life, I don't think I'll be running a whole lot more than during my week. I do other sports as well - I shouldn't need to worry about doing core/strength work (other sports take care of that).

So I'm going to have a fair mileage, but not that much intensity. I mean I can get a few interval in (say on the way back) but 7km isn't a lot of distance to warm-up, cool down AND do intervals. Also don't really wanna get to work already busted.

My question is: would it be realistic to aim for a 3:45 finish with that type of training/background, by summer's end (say 16 weeks from now)? Or am I likely to realize that I would really have needed some amount of higher intensity to really make that work?

Or put another way - how good can your marathon time get with mostly consistent mileage?

EDIT: my current pace going to work is ~5min/km or ~8 min/mile. My watches says I'm around 130-140 bpm. It feels like a good workout but I'm not exhausted and I think I could maintain that for at least 10 miles. I also ran a 10km race last week-end (flat, cool temps) and ran in 44 minutes and felt easy - I think I might have been able to do close to 40 if going all-out.

Answer 1

It sounds like overall you're on the right track. I'm a marathon runner myself and I was actually pretty taken aback a few weeks ago when I interviewed an Ironman coach and he spoke about the importance of 80/20 training (something I've never actually done)… yet I've run a marathon is 3:13.

Your marathon time will be as good as your training, nutrition, rest and pre-event preparation. You can also never discount the power of self belief, as fanciful as that sounds.

When in doubt, and if articles on the internet fail or mislead you (as they so often do), try and find a local running club or online coach willing to just give you a bit of advice for free. The most important thing is that you don't injure yourself with overtraining because that can derail everything.

Hope that helps!

Answer 2

First, you really need some long runs under your belt to know you are ready for 42k. If you feel you can do you 10K x 3 at 44 minutes then I would say YES to the 3:45.

It sounds like your speed is there but you are not sure about distance. I would recommend adding a Saturday long run to what you are already doing. Your runs will range from 17k-35k and should be 30-60 seconds slower than your marathon pace.

If you feel good at 32k and you have covered the distance in less than 3 hours then you are ready for 42k!