Posted: 16/02/2015 at 11:43
I'm 20+ years older than you, can do 24 min 5k and run 3 times a week totalling around 12 miles so there's no reason at your age why you can't beat me!(assuming you don't have any disability and aren't massively overweight)
If you run 10m or 20 or 30 a week at your 5k pace you won't get any faster, you need to do some shorter sessions at faster speed, replace one 4 mile run each week with either
- 5 times 1k with a minute rest in between at your target 5k pace
- 200/400/800 metres repeats with rest in between.
- hill reps - run fairly hard for 50?, 80? 100?m up hill, jog back down and repeat
If you always run at 28min 5k pace you'll always run at that pace, you need to learn to run faster and if you have limited time available it's quality that matters not quantity.
Think if it like learning to read. If you had always read the books you had when you were 5, when you picked up a more difficult book you wouldn't able to read it - it wouldn't matter how many times you read the easy books you'd never be able to read more difficult ones, you have to read slightly more difficult ones and whereas you could read the whole of a 5yrs book easily, you'd have been knackered at the end of a page of a more difficult one so gradually read a bit more.
Running's the same, if you keep doing the same thing you keep getting the same result.