Cannot Run 5K Time Predicted by My Mile Time

by Mark
(Phoenix, AZ, USA)

Couple years ago I started training for 5K races after a 10 year complete break from running, I am 44 now. I was just running more for fitness and fun, and noticed my mile time (5.38) predicted a much faster 5K time than I could produce. According to race conversion calculators I should have been able to run low 19s. But my times were around 20:15.

I realize this formula (like other performance calculators) assumes training for 5K to same degree as I did for the mile.

But that is the confusing thing, because I DID train more for 5K than the mile! I was running 3 times a week, 20 miles a week, mostly tempo type runs.

I decided I must have lost my 'base' over the 10 year break, and so was unable to hold the speed I have over distance. So for last two years, I have rebuild my base somewhat, running 40 miles week for a year, then last month Jan/Feb 2012 as going into 5K race reason for me, I've dropped the mileage to around 25-30 a week, and I've gradually added lactic threshold runs, and some Vo2max ( mile intervals) ..and I have done NO speed work i.e no fast intervals etc.

I don't know what my mile time is now, but my 5K is down to mid 19s ...still slower than that predicted time from 2 year ago! And I'll bet my mile time is in fact even faster now with no training for it!

This is true right down the speed curve, I can run 13 second for 100m, 28 for 200m, and 1.05 for 400m .....what is stranger still, I was college team runner at 10K, PB 33 minutes ..and best mile 4.40 ....and never a sprinter ..I was 130lbs 5'10 back then....I am 150lbs now ....mostly added upper body muscle ...so i'm wondering if the 10 years I took off running and built muscle has increased my speed at cost of lost ability to hold 'speed endurance' ...I know type II a fast twitch fibre's can 'swap'...so maybe I retrained them for speed?

Well, I am confused ... any thoughts would be appreciated on how I can fulfill my 'speed's supposed potential in 5K. Right now, I am running about 30 miles a week and training is as follows

3 quality runs/alternate recovery days as follows:

Sunday: Vo2x max/LT mile repeats ..4X1 mile @6.10 pace, 2 minute jog between (3 mile warmup / down)

Monday 2-3 mile recovery run (8-10 minute miles)

Tue 5 mile tempo run at LT pace 6:50 'ish

Wed 2-3 mile recovery run (8 - 10 minute miles)

Thur fartlek type...slow 3 miles, followed by 2 miles race pace

Fri 2-3 mile recovery run (8 - 10 minute miles)

Sat total rest day

I do some cross training on rest days, nothing hard, and some weights on the quality days straight after..nothing too demanded either..I do some plyo exercises as well..skipping, foot speed etc.

I feel the lactic threshold runs seem to be bringing the biggest improvement, to bring the speed I have up into 5K ...but is there anything else I can do?

My aim this season is to break 19 minutes, which I think I have good chance, but really feel I should be able to run 6 minute miles (18:30'ish) based on most prediction formulas.

Answer by Dominique:
Hi there,
Thanks for your question about achieving your 5k goal of sub-19.

Thanks for providing all the extra information. It's a lot, but let's try to work through it all as follows:

1. Usefulness of race conversion calculators
2. Changes I would make to your training

Usefulness of Race Conversion Calculators

First of all, a race conversion calculator is a very useful tool. But it is most useful when comparing recent races.

I am not sure when you did this 5.38 mile. If it is 10 years ago, it's of no use. You need a recent race to compare to. So, I'd be curious about your current mile time. I'd be even more curious about your current 2 mile time and whether your 1 mile and 2 mile are well aligned.

Because you see, the other thing to keep in mind is that these types of calculators work better when the races are more like each other. E.g. comparing a 100m or 200m time vs a 5k time is not as useful. Your comparison of your mile time and your 5k time is not bad. But a 2 mile is much more closely matched to a 5k. Whereas the mile is "a sprint that goes for too long", the 2 mile requires more endurance and a fraction less speed.

I suspect, as you say, you are a very good sprinter and less of an endurance animal. But I think you can make some changes to your training to build that endurance.

Changes I Would Make to Your Training

The thing I like about your program is the variety. You are doing some fast and some slower running. The fast running is also varied, which means that you are doing some work at faster than 5k pace, some at 5k pace and some at slower than 5k pace, which is fantastic.

So far, so good...

However, it looks like your running is quite heavily tilted towards faster running. Based on your training schedule you are doing about 9 miles of fast running (4 x mile intervals, 5 miles tempo, 2 miles race pace). And roughly 12-16 miles of slower running (including the warm-ups / cool-downs).

The 5k is much more reliant on endurance than you may think. All of that speed work needs to be supported by a much stronger base of endurance. E.g. I'd prefer to see you build up to a much higher mileage base. In order to achieve that, you'd likely want to reduce the more intense runs from three to one or two per week. And check out my page on increasing mileage safely.

So my recommendations are:

1. Re-establish a strong endurance base and get back to logging 40 miles a week consistently.

2. Build up the long run to at least 90 minutes in length.

3. Variety in the tempo work, I like the 5 mile continuous tempo run, but also do tempo intervals with about 30-40 minutes of total "work" (e.g. 3 x 10 minutes tempo or 2 x 15 minutes, etc.)

4. Variety in the intervals, I have got the feeling your mile-intervals are a bit on the long side. They are good for now and again, but I'd also make sure to do 400s, 800s, 1k, 1200m etc. Also check out my interval running page.

I hope all together that gives you a good idea about what needs changing in your current training, if you really want to have a go at a sub-19 5k. I think it is in your potential, and once that endurance base has been rebuilt, I'd be interested to see what happens.

Best of luck.
Hope this helps.
Kind regards,
Dominique