Doubling: Shortest "Allowable" Distance of Second Run?

You are over thinking it.

I said that I didn't plan on doing that, I wouldn't think that much. I'll most likely run as far as I feel like as a double. I'm just wondering (for the heck of it, no particular reason, not so that I structure my runs around everyone's advice) if there is much benefit to running that little for a double.

Sure there is. 15 minutes can loosen your legs up, etc. 85% of the time you'll feel good and extend the run from 15 min to 4 or 5 miles.

The more running you do the better.

15 min is fine, especially if you are just starting to double. It's a good way to stretch the legs and get the blood flowing. I think this is a more sustainable way to begin doubling rather than starting out with 30 mins. Pretty soon, you'll feel like bumping it up.

getting your body adjusted to being called upon to perform at a high level twice a day takes a bit of time. This is a fine way for you to adjust the social aspect of the new run-

new dinner time or reshuffling key AM bathroom slots(trust me your partner is not about to change the routine to suit your sweatypits), altering dogwaking times, kid to school type stuff or just plain getting your alonerunners ass out the door in the dawning light.

I love the short, slow-as-can-be morning runs. Regardless of anything else that they do (or don't do), they do make me feel stronger and faster for my night runs.

I generally run at least 5 miles for the shorter run, although I have gone as low as 3-4. If running a mile or two in the morning helps you feel good for an afternoon workout then go for it. It's probably better then nothing.

Can't remember where I read it, but ~30 minutes should be the minimum amount of time for aerobic runs (maybe Daniels or Lydiard said this?). Any less and the cost outweighs the benefits.

Lydiard said 20 minutes for aerobic benefit, but there's still a benefit from shorter runs.

26:30

Pfitzger says 25 minutes should be the minimum.

If it's a choice between nothing and 15 (or even 10) minutes, it's obvious which is better.

Do whatever you can.

Easy wrote:

Can't remember where I read it, but ~30 minutes should be the minimum amount of time for aerobic runs (maybe Daniels or Lydiard said this?). Any less and the cost outweighs the benefits.

Cost? What is the cost of running an easy few miles in the morning? Other then getting up earlier that is.

Honestly, I wouldn't even have to wake up earlier. It would just mean 20 less minutes of screwing around on LR in the morning.

15 or 10 min ???

And you people criticise RW. jeeze.

I recall Bowerman saying 7 minutes is the minimum for aerobic benefits.

I would always tell myself when first doubling and if too lazy in the morning, "well just go 15 minutes at least, you can do that". Usually after 15 minutes I'd be fine and end up doing 40 or so.

The key is going quite slowly at first as your muscles and tendons are much stiffer in the morning. More chance to injure them.

seriously to get any benefit you need to be putting in about 5-6 miles at steady pace- you will soon get into it and that 6am run will become the norm. Bit tough on cold rainy dark winter mornings- but its just got to be done