4 Journal of Aging Research Table 1: Continued. Authors (reference) Design/subjects RWuetlhsherafonrdd 1996 [33] 1e3i-0tyhmeearernhoiargnhnd-oinwmeopxmearcectniAsewEceXoren(ntarso=silgs1n(5ne)d=fotor15) Wiswell et al. 2002 [34] 54-old-male runners were intervened longitudinally over a 5- to 7-year period Bone measurements (BMD/BMC) DXA (Lunar DPX-L) (Lunar Corp., Madison, WI) DXA (QDR 1500) (Hologic, Inc., Bedford, MA) Results Exerciser had signiﬁcantly increased femoral neck BMD after 1-year training, while there were no observed changes in controls Hip and spine BMD were maintained by a 4- to 5-year running period compared to their baseline measurement DXA = dual energy X-ray absorptiometry, QCT = quantitative computed tomography. ∗Reference no. [9] did not show a positive eﬀect on bone and although it is discussed in the text, it is not presented in the table. Table 2: Snap-shot of the relevant studies∗ investigating the relationship of whole-body vibration and BMD of various skeletal sites. Authors (reference) Design/subjects Gusi et al. 2006 [19] Rubin et al. 2004 [13] Verschueren et al. 2004 [35] 28 postmenopausal women were randomly assigned to either WBV (12.6 Hz, n = 14) or walking group (an hour walking, n = 14) for 8 months 24 postmenopausal women were randomly assigned to either WBV (30 Hz, n = 12) or placebo vibration devices (n = 12) for two 10 minutes per day for 6 months 70 were randomly assigned to WBV (35–40 Hz, n = 25), resistance training group (n = 22), or a control group (n = 23) for 6 months Bone measurements (BMD/BMC) DXA (Norland Inc., Fort Atkinson, USA) DXA (QDR 2000) (Hologic, Waltham, MA, USA) Results After 8 months, femoral neck BMD in the WBV group was increased by 4.3% compared to the walking group. There were no observed change at the lumbar spine and other sites of the hip between two groups There was no diﬀerence between WBV and placebo group. Evaluating people with highest compliance, placebo lost 2.13% of BMD in the femoral neck but WBV group increased by 0.04% DXA (QDR-4500A) (Hologic, Inc., Bedford, MA) Total hip BMD in WBV group signiﬁcantly increased by 1.51% compared to control group DXA = dual energy X-ray absorptiometry. ∗Reference no. [36] is discussed in the text, but it is not presented in the table as it is a one-subject study. While these results did not demonstrate positive eﬀect on spine, they are consistent with the mechanostat theory that the BMD of a lower limb, a primary weight-bearing site, beneﬁts the most from running [42]. Ideally, running and walking could be an eﬀective measure to prevent the loss of bone mass for the older population; however, compliance with moderate to intensive exercise is questionable. Low-intensity AEX such as walking has a lower impact force upon the skeleton compared to running; therefore, it might oﬀer an inferior osteogenic stimulus. Walking as a physical activity may be beneﬁcial for postmenopausal women as well as elderly population, but it may depend on walking speed, with brisk and fast pace being more advantageous [27]. Krall and Dawson-Hughes [27] examined the impact of current and past walking on BMD in 237 healthy Caucasian women (43–72 years) and found that women who walked more than 7.5 miles/week had higher whole body, leg, and trunk BMD compared to those who walked less than 1 mile/week. Furthermore, the number of miles walked per week during a 1-year period was positively correlated with the rate of BMD increase in the lower limbs. A recent meta-analysis reported that walking had favorable eﬀects on hip, but not spine [43]. However, an earlier meta-analysis results showed that walking had a positive signiﬁcant eﬀect on spine but not on femoral BMD [44]. This contradiction is probably due to including the same groups of population twice in their analysis and the combination of other exercise modes with walking. Based on the observational and intervention studies investigating the inﬂuence of diﬀerent walking regimens on BMD [20, 23, 24], it was suggested that brisk and fast walking pace is more beneﬁcial in speciﬁc skeletal sites, for example, foot and calcaneal bones [20]. Ilich-Ernst et al. [23] evaluated the eﬀect of self-reported past and current walking routines (including normal, fast, and brisk pace) on BMD in older Caucasian women and found that both forearm and hip BMD were higher in the subjects that were able to walk at a brisk or fast pace. Similarly, in a 3-year evaluation of the eﬀects of walking and other habitual physical activities (not necessarily aerobic) on BMD in postmenopausal women, Ilich and Brownbill [24] reported that walking at a faster pace, involvement in sports/recreational activities, and even participation in low-impact physical activities were essential in augmenting bone mass. In a randomized study, it was shown that one year of brisk walking signiﬁcantly increased calcaneal BMD and slightly increased spine BMD, although not signiﬁcantly [20]. Similarly, a 2-year brisk walking regimen signiﬁcantly reduced loss of BMD at femoral neck,