How will increasing mileage affect performance?

Not a question of how many miles you run weekly, more about how you run your miles.

stop faffing around on low mileage and go all in, double most days, ramp it up to 100+mpw and you have the talent to run super fast times, maybe a 2.15 thon. now you're max 50mpw... imagine doubling that and how much extra aerobic capacity you will get.

Running is a fitness sport governed by the stress and recover principle. Mileage is one of many levers we can use to stress the body and if done properly it can cause an improvement in fitness. The art and science of training is understanding of each of the levers and how they affect fitness in each person and in different situations.

As someone trying to run longer races (HM and Marathon) then obviously mileage is an important level that you can use that will have significant effects on fitness. But the key to how much of a benefit you get will depend on how well you use it conjunction with the other levers.

My suggestion would be to seek out a coach with significant experience and success using these levers to help you navigate this.

Your PBs align fairly well, which can be rare with your speed + 45-50mpw. Maybe the 5k is a touch stronger compared to what you could do on the track. It's not, however, a crazy outlier that says more mileage will help you firm up your endurance & chip away at your long distance PBs. Mileage will still help. You're clearly talented. Training matters too. You must be doing a fair amount of quality & strength work to have those PBs all the way up. You could still benefit from working on your 5k/10k & then training for a marathon with the added mileage. 60-70mpw isn't even out there for a 2:27. Do you cross train? Play(ed) other sports? Ran in college but got injured a fair amount? I'm almost not buying 5 mile runs @ 8:30 pace/no strides/low mileage & these results. Get training & who knows what you could do.

Thank you for the feedback!

I ran one year of CC/TF at a D1 university about ten years ago. I focused on middle distance. Had PRs in HS/college of 50 for 400m, 1:57 800m, 4:05 1500m, 4:20 1600.

I understand the PRs not quite align with the training. 2025 was a complete breakout year for me as the last ten years I usually ran about 30 miles per week at a faster pace, usually sub 6:30-7:30. I was consistently around 16:00 5K and 1:13-1:14 HM. The only difference in 2025 was the increase to consistent 45-50 MPW, and my easy days went from 6:30-7:30, to nice and easy in the 8:00s so I could feel recovered (but more time on feet?).

Only really dealt with one injury but it wasn’t too serious. Don’t currently play any other sports but did growing up. I always run workouts hard and leave it all out there.

Thank you for the feedback! I plan on consulting with a coach.

Why didn't I get a "thank you for the feedback"? Rude AF. I hope you get attacked by a ferocious bear and can't even walk past a toy bear shop on the highstreet without having flashbacks and peeing yourself. But I hope you recover from your injuries and come back to the forum to seek further training advice post bear attack and I will be here waiting and we can make amends because I am big on second chances

30s faster over 5k would be a reasonable guess. Obviously a lot of factors other than volume but that 2-5% range is where most people end up . Some where in there a lot of people's experience diverge with some still improving a ton and others really leveling out. Do the work and see what you get

40-50mpw through college got me 16:13 5K. 100-120mpw, over 4 years, got me down to 14:50. Nothing got my 5K under 15:40 until I started averaging over 100mpw.

YMMV. Do it and report back.

In general yes running more will make you faster. Time on your feet wise you increased a bunch by running more mpw and by slowing down your pace. The key is running your easy runs at a pace that feels easy to you. Some days will be slower than others based on how your recovering from workouts. So in terms of increasing your mileage I would first try a cycle or the whole year doing 60mpw to make sure you respond to it first before increasing to 70mpw the next cycle or next year. Getting to 70mpw or so you’ll probably have to start doing some doubling depending on your schedule.

Gradually increasing your weekly mileage up to 60-70mpw should help your times come down at all distances but especially at the marathon and half marathon. Keep at it!

Mileage can really expose which event you can really be good at. I've seen runners who ramped up to 50-60mpw and couldn't even break 17:30 for the 5k but usually if you get to 17 low or even 16:20ish off like 50-60 miles a week of running then you have room to get to 15 high or possibly 15 mid the next year or so (depends on your training but you have room to get there)

To run that well off of 45-50 is already great. I would try 60-70, keep 2 recovery lighter days in there. Workouts, longruns, aerobic runs can be longer. After that try a block at 80-90 potentially. Mileage helps, but you have to be able to recovery while doing it.

That makes sense OP. Always something (not in a bad way) to these low mileage/good results threads. 4:20 is worth ~1:08/2:23, but you can get some 4:30ish types with great endurance going for times like sub-2:18 in the last OTQ cycle for example. You're still within striking distance of those optimized times so I would say mileage could be the missing component to knocking off a little more time. With your injury history/background, just be careful about increasing both mileage/intensity. Get the mileage up primarily with easy running/strides & then bring good workouts back in when you feel strong enough to take them on. You have the speed to go after an OTQ-type time if you're able (& willing) to go all-in on some serious mileage/training. You're also in a great spot now to make smaller improvements with a little more training if you're happy doing that.

I agree with the guy who said do doubles and increase substantially. Those are really quick times off low mileage. I made substantial gains going from about this level of mileage to about 70 to 80 in doubles (about 30 sec per mile improvement). Inwas a good deal slower, my 70 to 80 would be more like 80 to 90 for you. Build up slowly 10% every 3 weeks (that actually gets you to 75 or do pretty quickly )