How should I adjust my weekly running mileage when training to improve my 5k?
Let’s say you are starting out to improve your 5k from a good base and you know roughly what mileage you already achieve.
To avoid injuries obey the 10% rule. That is only increase your mileage by 10% each week.
Combine that every third week with a drop in overall mileage to allow partial recovery.
For a serious (but not-too-serious) evening runner I reckon that 20k a week in total is more that enough to get a male to 21 minutes for a 5k.