Can you please explain the announcement that came out yesterday, June 19, 2001, which stated that older women who have a high bone density are 50% more prone to breast cancer. I, as well as many of my co-workers who all use your program, found that statement particularly alarming.

You pose an excellent question that I'm sure other women are asking in light of this interesting research, which was published in the Journal of the National Cancer Institute. First, you should understand that this is not a causal relationship, meaning that having higher bone density does not cause breast cancer. The increased risk that is being seen is likely due to circulating hormone levels in the body--namely, estrogen and testosterone. More of these hormones in the body can lead to both increase risk of breast cancer as well as higher bone density.

So, what does this mean for continuing a strength training program in an effort to build bone density? You should continue. In our strength training studies at Tufts with middle-aged and older women we have not seen any increase in estrogen or testosterone levels, which is consistent with the opinion that strength training will not increase your risk of breast cancer--but it will help your bones. Indeed, numerous studies have shown that women who exercise regularly have a decreased risk for breast cancer as well as osteoporosis.