When base building butts up against race prep

I used to run and have done four road marathons, but that was several years ago. I'm starting to get back into it. I'm overweight, but have been trending back down.

I am going to run a trail HM in November. I've got a general outline of how I'm going to train, but it's not a carved in stone plan. At 45 I'm not sure how quickly/slowly I'll adapt to training and expect I'll need to adjust as I go.

When I lay out my general outline on paper, it looks like it's nothing more than a ramp up in mileage between now and November. Basically my base building butts right up against my race prep.

I know it's not ideal, but I'm not sure how to improve and still maintain reasonable training volume.

I've started running 3-4 times per week, - minutes, at least once on a trail.Ideally I'd like to end up with a long run of 2-1/2 hours and a med/long run of 90 minutes with two30-60 minute runs.

I don't know exactly what you mean by "race prep," but generally assuming that the term refers to more specific training for a certain event, I think that you actually want your base-building period to butt up against the race prep.

The idea is to use the base period to build up an endurance "base" so you can handle higher intensity training in the "build" phase.

Your base phase should last about 8-12 weeks and I think about 8 weeks is good for a build phase. Every three weeks you should take a recovery week that is much easier. It's very important to take the recovery week, and also be conservative about how hard you're pushing yourself--it should be a gradual build-up, which means that it should seem really easy for the first week of training, and then by the third week, as the fatigue builds, it will feel harder and you will be ready for some recovery.

Do some research on periodized training plans, it's a really effective way to train. The main trick to it is that you have to be disciplined: trust the training and don't try to do any "extra work" because this will wear you down and likely cause you to be injured later, and if you're injured, you're not building fitness.

Also, if your training plan is just a general ramp-up in volume and intensity between now and November, that's perfectly fine! More highly-trained athletes need structured training to improve because their fitness has reached a plateau but new/returning athletes will get rapid improvements in fitness from just getting out there on a regular basis and getting a feel for things is what's important.