Can a sub 4:30 mile be done without any speed work?

It's a very thought-provoking question. Conventional wisdom says you would need to touch at least the goal pace occasionally, but perhaps with some creativity, you could run sub 4:30 without training under 6-minute pace. Here's how I would try it: running training would consist of four days a week right at 6:00 pace on hilly terrain including the long run. The other three days could be normal easy runs on flat terrain for recovery. Now here is where the creativity comes in. In the gym, crush neuromuscular/power and range of motion stuff. Things like jumping rope, box jumps, and power lifts should get the job done. Combine that with a lot of mobility work especially at the hips (extension) and ankles (dorsiflexion), and I think you can get away with it. About two weeks out from race day, do a short CrossFit-style workout with the power movements as an acidosis tolerance stimulus. I don't like to think of training as merely checking boxes, but you can check all the boxes even with such limitations.

As an aside, it would be much easier to create the inverse limitation: never allowed to train at 6-minute pace or slower, but I digress.

A 431 miler wrote:

Given that constraint, would any of them break 4:30 given sufficient motivation?

No

Or is speed work required to run that fast?

Yes

.... unless someone has a TRULY rare gift.

I can tell you that somebody ran sub 4:10 this year without doing any training under 5 minute pace so he easily could have run 4:30 on 6 minute pace training.

Big Boy in the NCAA wrote:

I can tell you that somebody ran sub 4:10 this year without doing any training under 5 minute pace so he easily could have run 4:30 on 6 minute pace training.

Your sub-4:10 miler either races all the time, one mile or shorter distances, which is similar to doing workouts. Or, your sub-4:10 miler did 200m or 300m or 400m or 500m or 600m repeats at one mile pace or faster years ago thus muscle memory.

A talented runner could easily go < 9' 2mi , and possibly <27' 6mi.

Your constraints allow for long hill reps at high altitude or short reps up steeper sand dunes or though heavy snow, perhaps pulling a sled or some other resistance.

Running 6'/mi at 4% incline is actually a fairly challenging workout.

A 431 miler wrote:

The only rule is that none of them can ever run faster than a 6 min/mile pace

Has never run faster than that AT ALL?

Not a chance.

A person who has never thrown a single sprint or surge under a slow 22.5s/100m cannot suddenly run 16 continuous 100s at 16.8s per 100.

If they have never jogged 6:00 pace even for a moment in running or another sport, they are not suddenly doing a 4:30.

So you picked a good cut-off time as I'd say that 4:30 is roughly the time a talented athlete could run without speed work per se but it's complicated and it comes down to what you consider speed work. Is the person doing other sports such as soccer or football where they are in fact running fast albeit it not under track training conditions per se? I ran the mile and 400 meter relay in HS and we didn't do much speed work per se as a team but I raced lots of 400s and lots of mile races so would that be considered speed work? If you are asking whether someone who only runs 6 minute mile pace or slower can run 4:30 cold in the mile I'd say its possible if they are a strong athlete in other sports but I think that is due in part b/c they are at times running around and engaging in activity other than running during the course of their every day life. Likewise if you ran longer distances as slower pace, did weightlifting and plyometrics, core work and perhaps some cycling or other activities one can probably run 4:30 but...why? If someone has the fitness and natural ability to run 4:30 they will definitely get faster if they incorporate some 200s and 400s into their workout.

We had a state champion high hurdler on my track HS team, he was pretty solid in the 200 too but never ran further than 200M in any competition until he competed in the state decathlon meet his senior year. he pulled out a 4:19 1500 having never run the distance before basically because he was a stud of an athlete (state champion wrestler and a stand out football player). I'm pretty sure if he trained longer distance he could have run a faster mile / 1500 but at 6'2 he was a much stronger sprinter (and a pretty good high jumper).

Absolutely yes. I have trained with some really talented runners in my life and seen them respond to mileage alone. Think of a guy with the talent to run sub 4, he could run 100mpw for a year at 7:00 pace and then bust a 4:30 for sure.

4:30 pace is 67.5/400m, that is not "fast" in the sense that you need to develop special coordination or muscle memory for it.

How do you know whether you have the talent to run sub-4 though? Asking as someone who started running in their 30s and wondering if it's possible to respond more to high mileage vs speedwork as the latter is less on the table due to injuries.

A 431 miler wrote:

Suppose you get to pick a large group of people who have never run a sub 6 mile before and get to coach them. The only rule is that none of them can ever run faster than a 6 min/mile pace except for during their one and only sub 4:30 mile attempt.

So that pretty much means no intervals, no strides, no hill sprints, and no time trials or races over short distances.

Given that constraint, would any of them break 4:30 given sufficient motivation? Or is speed work required to run that fast?

Obviously, it is possible if you get a talented enough runner. You probably need someone who could get into the low 4s with speed training. The first year you gradually get the group up to 50 miles per week. Even for a 4:30 miler, you can get a really good workout going for an hour or longer at 6min/mile, as this is close to marathon race pace for a 4:30 miler who has yet to build a monster base. They'll do easy runs a bit faster than I'd typically recommend given that none of their workouts are that fast. So they can eventually do easy runs at 6:50 -7 min/mile. Typically I'd expect a 4:30 miler to do easy runs at 7-7:30 pace.

Hazel wrote:

How do you know whether you have the talent to run sub-4 though? Asking as someone who started running in their 30s and wondering if it's possible to respond more to high mileage vs speedwork as the latter is less on the table due to injuries.

Yes it is possible. Older people tend to respond well to high mileage with very minimal workouts 1-2 per week, including races (1 tempo, and one interval session, the rest easy miles, including a long run at easy pace)

Yes

I ran a PR one summer, jumping into an all comers meet, of 4:36. My lifetime best ended up being only 4:27.

I doubt I ever went faster than 6:00 pace that summer. I certainly wasn’t doing organized workouts. BUT almost every one of my runs was pretty hilly and I had a tendency to try and push pretty hard every time I got to a hill.

Some runs went uphill for 3-4 miles straight, so there’s your tempo effort right there. Other runs had lots of hills that each took 1-3 minutes

I was not super talented, so if I can get that close doing what I did, I’m sure there are people out there who could smash 4:30.

I didn’t fit OP’s parameters because I’d already run 4:17 for 1500 and 16:18 for 5k the previous track season and we did plenty of speed work during the season.

OTOH I remember the first race of German Fernandez’s career where he split 3:18 for a 1200 on a DMR after less than 3 weeks of practice as a freshman. He’d come out from the JV bball team and played football in the fall instead of cross. I know for a fact that he’d done some intervals, but I’m sure he could have done it without the intervals as well.