What would happen if I did nothing but tempo runs?

You would be a throwback to the 1990s - the worst period in American distance running history! Low miles. Everything at a moderately hard pace. No real recovery. And lots of mediocre performances.

Another way to think about his is according to the principle of specificity: your body will adapt and become better at what you do a lot in practice, within some narrow range like +/- 5-10%, with respect to both speed and distance.

It still depends then on how that is distributed during the week. For example 5.7 miles/day, 7 days a week will produce a different stimulation and adaptation than three sessions a week of 10mi + 10mi + 20mi or a two sessions a week of 20mi + 20mi. Sessions of 7x5.7mi per week will make you better at "tempo-ing" 10Ks with less effort, while the latter sessions with 10mi and 20mi workouts will improve your half-marathon and marathon performances -- but there are better ways to train for the half and full marathons.

Can't really say anything is your 'marathon pace' without having a recent marathon time to use, assuming they are in 36x mins 10k shape his marathon pace could be 6.25, 6.30, 7.00, even 7.30.

Ignoring what yoda/malmo above says, 6.30 is a decent 'tempo' pace for the OP if you had to pick a pace to aim at do a 20-30min run 6.30 seems logical, not everyone likes to go on some magical 'feel' when they do a run.

I actually know someone who runs 10k around 38x, half around 90mins, and marathon 3.15, and he does ALL, and I mean ALL his runs at 6.30-6.45 pace, even the first mile. Can't fathom how that's enjoyable but each to their own. As to the effect of this, he is often complaining of painful knees, and rarely races at a pace much faster and hasn't improved.

Note the OP is asking a "theoretical question" -- and I said "*estimated* marathon pace". Of course, with actual times we could be more precise, but this is a theoretical exercise without really much background information to go on, nor well described constraints. Without a recent marathon time, you need to start with a reasonable "estimate" based on the recent time given for 10K.

For a 36:50 10K, McMillan gives a range of "stamina paces" as fast as 5:54 for "Tempo Intervals" (or even a faster 5:48 for Daniels-style "Cruise Intervals") to as slow as 6:31 for longer "Steady-State" runs. 6:30 pace is just at the slowest end of this "stamina" pace range, and estimated MacMillan marathon pace is a slightly slower 6:36. Daniel's estimates a slightly faster marathon pace pretty much exactly at 6:30.

There are many ways to estimate paces, but they won't change that much between the most common methods. I only use "marathon pace" to give perspective of how slow this explicitly selected "tempo" pace is. If the theoretical runner actually improves his stamina with this single training at 6:30 pace, not faster or slower, then this training pace will become proportionally slower, like his estimated 50k pace or 80k pace.

I agree with "malmo" that "tempo" isn't a single pace to hit, but can be as slow as marathon race pace, or as fast as 10K race pace, depending on which stamina workout you are doing, and a few other factors. I think of "tempo" as a synonym for "rhythm" rather than linking it to any pace, and prefer to speak about training in result oriented terms of improving target variables like stamina and speed and endurance.

In an interview with GQ last month, Galen Rupp spoke about how speed and power helps maintain form and that your body will look to do the easiest (although not necessarily the most efficient) form if you only run easy/tempo paces all the time. I imagine only doing tempos would probably exaggerate whatever weaknesses/imbalances you have and negatively impact your stride after a while.

You’d probably post about it every day here

It's a really, really, shortened and scaled down version of what Ron Clarke and his training group did and it worked very well for them. My college roommate also did this for most of he year but at nearly a minute per mile faster. He got 15:04/31:20 for three and six miles.

Can confirm ^

This is such a horrendous take. Sell’s Marathon Pace was close to 5:00, so him running 6:00 everyday is like a 2:38 marathoner running 7:00 everyday. That is extremely easy to do and in no way “a tempo every day”. He just didn’t have as polarized of training as some other people

Is your goal here to be helpful? Or to imply superior knowledge without actually offering any concrete evidence to back up a nebulous stance. Asking for a friend.

Not true

Since the entire thread is about the idiosyncratic and hypothetical idea of regimenting and repeating the exactly same run each day, this is a good point but somewhat moot. The thought experiment posed by the OP includes a specific pace, and it's his thread.

You just go against the more important thing to improve your performance. Thats Modulation . Alternating hard days with easy days ,and also variation of training stymulus , repetition , Vo2max , threshold, marathon pace, easy and moderate run, hills , sprint . You need to train to all different speed then of course you will put more attention to the speed of your specific event but also the speed near your main event will be very important to support. Training only with tempo run not only will be very boring but you will give only one type of stymulus to your body , is it like if you want to write a good book but you pretend to use only a few words or if you want to paint and you can only use one color . You can be the best writer or painter but sure will be very hard to express youself at your full potential . Remember every speed is important in training , the focus will be on your event speed but also the speed a little slower and a little faster will help to reach your best performance and shape

this is how i train, for the most part, i do throw in some speed work once a week, not 40 miles consistently but 20 to 40 every week. I have not been hurt in the 4 years since i started doing this and run mid 16s for 5k. There is a plateau but whatever, i am 37 years old and dont have time to put in any more than I am currently.

You could do interval sessions and easy runs at the same amount of time? Would get sick of doing runs in the same intensity all the time.

I already do that but my tempo pace is 830

If you run all your runs at tempo "feel" not exact pace you'll improve. Some runners have better luck with all moderate approach than easy/hard. Think Mark Nenow and others from the past.

Depends. Some people, ex those with actn3xx dont need the same amount of long runs.

The distance you commpete in is also a factor. Lack of lactate work will punish in half maraton and competition faster than your workouts but can be good for economy at same speed such as for ultras.

quality does not always replace quantity. it shows that you have more potential. if 800m runners do 40-55 miles per week and milers do 70-120 miles per week, then you are way under your potential for the 10k distance. 70 should be the minimum for you. now it might be understandable if you don't have the time or motivation to do 70 mpw, but you can't simply replace mileage with higher average speed. without doing a mix of long runs, speed runs, recovery runs, etc, you won't improve very much