Hey Rob,
So it's a bit easier to explain training volume when talking about resistance training rather than running, but some of the same ideas apply. So in the gym if you do, for example, 4 sets of 10 repetitions of 20 kg weight for say, barbell biceps curls, your volume for that exercise would be 4 x 10 x 20 kgs = 800 kgs. You could add this up to see your weekly totals and manage your progressions over time using these numbers.
For running, distance is the easiest overall measure. It's relatively easy to look at your weekly distances. The main reason for keeping track of this would be to avoid injury or to try to gradually increase your speed or distance that you're able to run (if this is one of your goals). If you're normally running 40 kms per week and then suddenly jump to 60 the next week, you may or may not run into issues, but it's definitely something you'd want to know. You might also want to know the speed and/or intensity that you're running at because 40 kms run at 10 kms per hour versus 15 kms per hour might be very different for your body.
Running on the treadmill is great! You will likely find that this is the easiest on the body, compared with running outdoors. If you do start running outside, different surfaces can either be harder, softer, flatter, uneven, or even slanted for drainage. So there are lots of things to consider. Ideally, you'd want to find a surface that's flat and level - like a running track or asphalt sidewalk - and not super hard, like concrete. Or just start off slowly - you don't want to just suddenly do the same distances outdoors that you can do on a treadmill.
I hope that helps a bit, let me know if anything doesn't make sense or if you have more questions!
PLB, This is so helpful. I read and hear other runners mention mileage per week. What you’re saying clicks. I have never really focused on this though. The running has been more just go out and do it and get a feel for it as I go. I have a good intuition about what I can/can’t handle but I certainly see the benefits of managing things through tracking and paying attention to how my body performs and feels. It’s one thing at a time for me now and I’m still working on better logging so I can start to see a bigger picture. I will tweak from there and try to continually improve that process and add to it. I will have questions along the way. Thanks again so much!
I have done a lot of running on asphalt outside. I used to prefer it and hope to get back there. They say to increase the incline on the treadmill to 1% to mimic running outside which I've been doing some. I can tell now more than ever that things like the weather, inclines and uneven surfaces make a big difference over a 5-6 mile run.