The purposes of this study were to evaluate the effects of a walking routine on bone mineral density (BMD) at the lumbar spine, at the femoral neck (a part of the hip), at the radius (wrist) and for the whole body in perimenopausal and postmenopausal women and to identify the optimal duration of a walking program. The study reported on randomized and non randomized clinical trials through systematic review and meta-analysis of those clinical trials.
Ten data bases were searched from their origin through December 2012. All randomized and nonrandomized controlled studies on walking interventions in perimenopausal and postmenopausal women were considered. Efforts were made in the analysis to avoid double counting of participants in the meta-analysis papers. Only studies that evaluated walking alone as the sole exercise program were included. The outcomes were defined as BMD at the lumbar spine, femoral neck, radius and whole body, as measured by single-photon absorptiometry (SPA), dual-photon absorptiometry (DPA), or dual x-ray absorptiometry (DXA).
From these searches, 229 articles for potential inclusion in the review were found and identified but in the end, only 10 trials were eligible for inclusion. Among those 10, seven were randomized controlled trials. Participants were predominantly from the U.S., UK and Japan. Walking for 40 to 60 minutes per session was reported in 8 of the trials, with one being two levels of 45 and 30 minutes per session and another only 30 minutes per session. The frequency of the walking was approximately 3-4 times per week in 9 of the 10 trials. A meta-analysis of trials evaluating lumbar spine BMD showed no significant effects regardless of the length of the exercise program. When all the ten trials were taken into account, walking interventions with durations of 3 months to 2 years were NOT found to have beneficial effects. However, two of the meta-analysis did observe a significant positive effect of walking on the BMD at the femoral neck. These two that showed this increase were the programs that were at least 6 months (vs 3 months) up to 2 years. It is thought the difference between the negative results and the positive results is in fact duration of the walking program. The effects of walking on the radius and whole body were not significant.
Commentary: Menopause is a major risk factor for bone loss in women due to the lowering of the body’s natural estrogen level. Low BMD increases the risk for osteoporosis and fractures. Several recent reviews have investigated the effects of walking but the conclusions were inconsistent. Two randomized controlled trials have demonstrated significant effects of walking on BMD preservation. A Cochrane Review based on 3 randomized controlled trials showed not significant effect except in the spine. The Nurse’s Health Study suggested that the risk of fracture was reduced by regular walking and others have shown no benefits or just modest benefits on BMD after 1 year of walking.
In this systematic review, walking for 40 to 60 minutes per day, 3-4 days per week showed almost no benefit to BMD except after 6 months and at the femoral neck only. If that were just the whole story, it would not be that compelling as a treatment strategy to preserve postmenopausal BMD. However, walking has been shown to decrease the risk of many diseases such as congestive heart failure, stroke, type II diabetes, high blood pressure, high cholesterol and even some cancers, and even as a fundamental treatment for weight management, PMS, depression, high blood pressure, type II diabetes, high cholesterol. Women don’t have just bones of course, and have many compelling reasons to walk a minimum of 40 minutes, 4 days per week.
Reference
BS D, Wu L, He Zhong. Effects of walking on the preservation of bone mineral density in perimenopausal and postmenopausal women: a systematic review and meta-analysis. Menopause 2013;20(11): 1216-1226.
