People don't seem to realise that running on pavement ***** your knees up, might not seem like it at the minute but as you get older they will likely be wrecked.
i personally do not think that is completely true.
first of all you have to take bio mechanics into the equation, it is the biggest factor on how much shock the knee's have to absorb.
if you run say with 100% proper natural biomechanical movement, in a decent pair of running shoes (measured to your style), then i reckon the wear and tear of your knee's cartilage would be minimal even when running on pavement, because your feet and ankles will absorb most of the impact then your calves and lastly your knee will get just a small amount.
obviously though it would be better to run on something softer like grass (which can be a huge problem when it rains, which is roughly 300 days of the year in Scotland, so i would get maybe 60 days at best a year to run on grass), or a track be it indoor or outdoor, but i dont think i have one locally that is "free".
physio say's i have bad bio mechanical movement, but tbh there's nothing i can do about it, my chiropractor say's my right leg is half an inch longer than my left leg (i had never noticed this in all my life until he told me so a couple of years back), and i can feel it is now when I run, both my feet land completely differently.
so therefore it's literally impossible for me to correct it, especially since this is how i have been running my whole life, it would be pretty hard to change it all now.
therefore i stick to a treadmill.
also the cost of a treadmill when you separate it out over several years is literally nothing compared to some of the crap that people on here buy.
take a look at all those guy's buying star trek magazines for instance in the GD thread, then there's guy's who are over 20 stone in weight paying hundreds of pounds on a regular basis to watch live football, etc.
personally i would rather be playing football than even watching ronaldo and messi in the flesh, it's far more enjoyable, sadly my knee doesn't agree with me, and i suppose it is ironic that it was injured whilst playing football.
i mean my treadmill was around £950, spread that over say even 3 year's and your talking less than £1 a day, hopefully my treadmill lasts more than double that though.
anyway it's bad bio mechanical movement which messes up knee's more than anything else tbh, with the correct movement, the shock should be so little that your knee's should theoretically be fine.