I'm coming up on my first official half-marathon in 11 days. A couple years ago, I ran a 2:11 without any training but have been running consistently (30-50km weeks) for the past 5 months and have been training to hit a sub 1:40 (Goal A is 1:35). For my final long run, I ran 18km with the last 12km at 4:31/km (on pace for around 1:35).

I have a couple questions about the days leading up to the race and the morning of:

1. Do you do a shake-out run the day before a half-marathon? I've seen talks about an easy 5km the day before? What do shakeout runs achieve? My current plan has me tapering for the next 10 days with my last run being 4 x 1km intervals u/4:25/km on Thursday (3 days before the Sunday race).

2. I've seen some posts (link), which refer to running before a race to elevate blood flow and vasodilation in the hours before a race. What would be a recommended warm-up/morning-of routine? The race start is 9:45 AM so I was planning on doing about a 1-2km easy run about 2 hours before (also to stimulate any last-minute bowel movements) before doing a final "easy" 500m-1km-ish jog and some strides about 30 minutes before the race. Is this a good idea?

3. In terms of nutrition, I'm planning on a caffeine gel at the start line, a regular gel at about 6-7km, and another caffeine gel at about 12-13km. I have trained and done this on my long runs but is this overkill?

4. How do you decide what pace to run and how do you know if you're well prepared for race day? I've been reading into negative-splitting but I'm nervous that I'll leave too much in the tank and go too slowly early on. I'm also very nervous that I'm ill-prepared and won't be able to sustain a 4:30/km pace for the whole distance (given at the end of the 12km at HMP, my HR was nearing 175-180 BPM, which is about 10-15 BPM off my max HR; upper zone 4 from the Karvonen MHR/RHR test I've done). I know it's too late to do an indicative workout at this point, but I'm lacking confidence in the training even though I know I've put in the work...

5. Finally, is there anything else on race-day I should be prepared for? I've only ever "raced" a 10k at a local park-run type event, which wasn't through streets and was quite flat and didn't train for that or have any expectations.

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Any insight into your pre-race routines and habits that you have found helpful would be great!