I had a dexa scan a couple months ago that showed mild osteoporosis of my spine, hip area somewhat better. My friends couldn't believe the diagnosis because I backpack and do trailwork and lots of weight-bearing things, but of course I don't do those things 3 times per week. So I've been doing some reading on the subject. According to one book, walking is such mild weight-bearing exercise that it is unlikely by itself to increase bone density (at least in a one-year time frame). Jumping exercises were experimentally demonstrated to increase bone mass. I have a question maybe Knot or someone can answer (though it's likely no experiments have ever been done to determine this for sure). If I have a 2 mile commute to work and want to increase the bone density in the spine, which of these commuting methods would be best, or at least useful: walking, jogging, walking with a heavy backpack, cross-country skiing, snowshoeing, cycling. I'm not likely to jog due to knee issues, but the others are viable, depending on conditions - though lack of any sidewalks on the busy streets of my commute makes cycling feel safer. Any evidence that carrying a heavy pack increase bone density in the spine? Does it matter if the backpack weight hangs from the shoulders or sits more comfortably on the hips?