I suspect they tend to predict unrealistically fast marathons based on shorter distance performances specifically for young men whose training experience is mainly high school and maybe college track and xc. A more mature athlete or a woman of any age with the same shorter distance performances would likely come much closer to their VDOT-based performances than a relatively lightly-trained young male.
AndyRR wrote:
10k: 35:30
Half: 1:18:30 (14 months ago)
Full: 2:53 (~3 years and 10 months year ago)
Almost exactly the same here. In relation to my other post a minute ago, all of these were at ages 20 or 21 for me. I ran within a minute of both my marathon PR and half marathon PR when I was 30, probably couldn’t have run within 2 minutes of my 10K PR, and was probably more nearly equally well trained across the full range of distances (I.e., as well trained as ever for a marathon; not particularly well trained for a 5K or 10K).
OP, I agree with everyone who’s said 2:45 is ambitious. A few years ago as a 30-year old guy, I ran a 17:03 5k, 35:39 10k, and a 1:18:49 half, so pretty similar to your PRs. Like you, I averaged 50-60 mpw during my marathon build. Despite my shorter distance times predicting sub-2:45 in the JD calculator, I settled on a goal of averaging 4 mins per km (2:48:46) to give myself a cushion for sub-2:50.
I ended up running 2:48:04 and felt pretty good throughout, though the last 3 miles were a real grind. I don’t think I left much time on the course. Had I tried for sub 2:45, I would’ve bonked hard. The guys I know who can run under 2:45 off 50-60 mpw can also run under 35 for 10k and under 1:17 for the half. If you can get to that level, then 2:45 will be much more attainable. Whatever goal you ultimately decide on, I hope you crush it! Let us all know how it goes.
I like the JD calculator for comparisons and efforts but still take it with a grain of salt since it cannot account for effort, course difficulty, nor race execution. However, I find them to be helpful to assess where your fitness is compared to other times you have raced well.
I have some similar PRs to you across the board. 17:02, 35:40, 1:19, and 2:49.
I ended up running some good quality and stayed healthy, but only kept mileage around 55mpw. I had my eyes on sub2:55 since I tend to trail off as the distance increases but after going through in 1:26ish, I was able to get after it and cut a negative split.
It's all about setting yourself up for success. If you think you're in shape to run near 2:45, going through in 1:23-1:24 isn't gonna kill you but hitting 1:20 will probably tank your race.