As I wrote earlier, walking uses 112% of body weight as far as a weight bearing exercise. That translates that it is beneficial for bone density. However, is walking enough? Most of us walk all during the day just to get from point A to point B. If walking was enough to build bone density, the majority of women would be much better than is currently reported. Bone is smart like muscle and adapts to the workload. For example, if you are doing biceps curls with an 8# weight at some point your muscle becomes accustom to the 8 pounds and you have to increase the weight to get stronger. Just adding more time to the walk isn't the answer either. You would eventually be walking for most of the day to build stronger bones. The answer is to add more intensity. For those of you that can, do some intervals of faster walking (walk slow for 3 houses and fast for one) or add some hills to your workout. If you walk on the treadmill, make use of speed and inclines. I use a weighted vest several days a week either on the treadmill or elliptical or a combination of both. It's not for everybody so think before you act. The benefits of walking are numerous. Walking is good for the heart, weight management, balance, and managing your blood pressure. Keep walking! If you depend on it for building bone density, think about intensity.
Resource: ACSM Action Plan for Health Series Action Plan For Osteoporosis
Kerri Winters-Stone, PhD