How do you know how much you should run? What volume per week is right for you?
Running volume is basically a fancy word for the amount of mileage/time/distance you are running in a given week. As an athlete and a coach, I've learned over the years that every individual is completely different on what volume of training works for them (and works for me)
Some runners thrive with high volume, over 50+ mpw, some runners train on a smaller weekly regime, while the pros clock in around 110-130 or so a week. Most people don't run over 100 miles a week, but the general, 'normal' runners have a wide range of miles they run per week. And each person needs to know what works best for them.
A lot of this comes down to age, fitness level, lifestyle, commitment, goals, etc. For instance, when a runner is in peak marathon training they are runner a higher number of miles a week than they normally would on an average week of training. Age, fitness level and life circumstance (pregnancies', babies, work, etc.) all play a big role in this too.
One way to learn how to determine what is right for you is simply to test out different volumes. Adding volume takes time and it is important to build slowly.
Let's say you are at 20 miles a week, average. Slowly build your way to 30 (this may take a few week or more) and then stay there for a while. Feel it out and see what fitness gains you notice. If you want to push more, increase your mileage and stay there for a while. Are you feeling good? Burnout? Any aches/pains/twinges? Sometimes, it takes testing out different territories to know what works best for us.
For instance, I feel really good when I sit around 30 miles a week, but I know to have some good races/get faster and fitter I may need to increase to 40 or so. I'm, also, personally really curious to know how I would preform and feel on 50+ miles a week.
The running volume game is a long game. It takes time to build (although maintaining is easier one you get there!) and it is important not to build too quickly.
If you aren't in serious training for anything right now, feel free to play around with the mileage and slowly add mileage as you see fit. You will notice changes and most likely you will get fitter and faster in the process!