I have trained for a half marathon and other similar length races several times. Personally speaking I think the long runs are very important and total mileage, short runs, and fartlek are overrated. That to me seems common sense and fits with my experience, although keep in mind it is different to much expert advice.
If you can run 6 miles now suggest run at least one long run a week until the half-marathon. What worked for me was each run, I run 1 mile further than the previous week even if it is tough to do so. If it is easy to do so, I run 2 miles more than the previous week. As long as I do that once a week run and build up to 8,9,10,11 miles a week I'm fine. Remember to build in time for injuries and illnesses. Having hit a maximum of say 9 miles 1 month before the race seems OK until you get ill or a small injury that puts you out for 2 weeks, then you realize your training schedule had no safety net.
By the way, suggest not to make 9 miles your longest run and then struggle through the race on the day. Make 11,12 or 13 miles your longest training run and then enjoy the day more. My longest training run before the London marathon was 25 miles. Boy did I enjoy blasting my way down past Big Ben and down the mall and overtaking people at twice their speed! That is where the training pays off, instead of hobbling over the line to say never again and end up stopping doing all exercise for months after the race.
I'm wondering if it's a good idea to not to run on the treadmill exclusively, but also outdoors at least once or twice over a longer distance. Just incase something is different you need to discover that before race day. For example if your treadmill is soft and cushions your feet, then you run on the road and it jarrs your knees, or you suddenly find you are not used to running in direct sunlight and didn't drink enough before the start. But perhaps you've already thought of that.
Consider if the half-marathon is hilly, and is it on pure tarmac or other terrain. However, if you can't replicate the actual half marathon exactly, you can just get fitter. For example you can train for a half marathon on hilly off-road tracks by training on hilly off road tracks OR just by training to a higher level. If you can run 15-16 miles on flat tarmac or a treadmill you'll be able to handle 13 of hilly cross country.
I personally find 6 miles easy to run on little or no food, but then start to struggle energy wise after about 8-12 miles or so. You'll need to prepare your food intake for a 13-miler. For some people that will mean eating a large meal 2 to 2.5 to 3 hours before the race, for others a small meal will do. Still others can just eat a banana before a half marathon and have some gummi bears in the pocket on standy (for example, although these might be with gelatin and not be vegan, but it was just an example). Others might prefer to just drink water and eat after. Everyone is different. But start to practice eating before your 6,7,8 mile runs to make sure can judge your own personal needs on how much to eat and how long before. This is to avoid suddenly discovering in the late training runs, or even on the day of the race, that you can run say 10 miles without specific food planning and hit a wall at 11-12. Food planning for half marathons is fairly easier compared to marathons. Just don't neglect to consider altogether.
That's my advice although to be honest if you run six days a week you probably don't need much advice and I'm kind of giving advice for someone who's not run a half marathon before, so if you already have this is probably a bit much so sorry.
Last edited by Jamie in Chile; 01-05-2018 at 12:47 PM.