###### Abstract
[14] referred to an even distribution of left-right (50.31%: 49.76%) and a forefoot loading of 39.87% based on the study of 30 subjects (28 w/2 m) between 18 and 35 years of age. The equal left-right distribution was also confirmed by [PERSON] et al. [15], with 628 (241 w/387 m) asymptomatic subjects aged 6-89 years; however, in terms of forefoot and rearfoot loading, it showed an almost symmetrical loading (46.05%/52.63%) in contrast to other authors [13; 14]. Furthermore, all quadrants showed an almost identical weight distribution (approximately 23% left/right forefoot: approximately 26% left/right rear foot) [15]. Regarding the balance distribution of 416 subjects (208 w/208 m) aged 18-65 years, there was no gender difference observed by [PERSON] et al. [16]; the left-right distribution (50.07%/50.12%) was consistently balanced. However, with increasing age, the left rearfoot load reduced in favor of the left forefoot load and, overall, the rearfoot was found to be approximately 10% more loaded than the forefoot [16]. Similarly, data published by [PERSON] et al. [17] from 108 healthy subjects (51 w/66 m) show that the rearfoot is loaded 60%, the metatarasus 8% and the forefoot 28%. Consideration of isolated age groups has also demonstrated a relatively balanced left-right balance distribution as well as forefoot and rearfoot loading in women aged 21-30 years (L 49.91%/R 50.09%; FF 33.33%/RF 66.67%) [18], 31-40 years (L 51.46%/R 48.54%; FF 33.84%/RF 66.16%) [19] and 41-50 years (L 51.00%/R 48.5%; FF 29.67%/RF 70.63%) [20]. Regarding the reference values of the postural variations, these are presented differently. [PERSON] et al. [21] and [PERSON] et al. [22] used the ellipse area as a reference for postural sway, which was reported as being 70 mm\({}^{2}\)\(\pm\) 40 mm\({}^{2}\) by [PERSON] et al. [21] and 71.83 mm\({}^{2}\)\(\pm\) 54.56 mm\({}^{2}\) by [PERSON] et al. [22]. In the 21-30 age group, men showed larger frontal and sagittal variations (11.67 mm/13 mm) [23] than women of the same age (9.5 mm/13 mm) [18]. Evidentially, frontal and sagittal balance variations increase with age, as can be seen on the basis of 41-50-year-old women with 13 and 16.5 mm, respectively [20]. However, lower values can also be found for the group of 31-40-year-old women with variations of 8.17 and 12 mm, respectively [19]. Thus, in times when raising the retirement age is virtually unavoidable in order to maintain the prosperity of society, the working and performance capacity of the economic population should be maintained for as long as possible [24; 25]. In view of an aging society, the present study has the ambition to collect reference values for women aged 51-60 years and, as this study is of women only, gender differences are avoided, e.g., in constitution [26], BMI [26] and hormonal balance [7]. It is to be expected that for women, their occupational work and performance, due to the foreseen increasing compatibility of family life with work, will become an important focus in society. Therefore, the age group of 51-60 years is especially interesting since women of this age are often no longer the focus of child rearing;this enables them to return to full-time work. In addition, the majority of these women might be within, or relatively close to, menopause which normally occurs between the ages of 48-52 [7]; this means that little hormonal variation is expected within the group and the negative effects of a deficiency in estrogens are also still relatively small. A deficiency of estrogens, which occurs after menopause, can lead to osteoporosis among other things [7]. To date, reference values are available for men in the age range of 21-30 years and for women in the age ranges of 21-30, 31-40 and 41-50 years [18; 19; 20; 23]. These studies, as well as the present analysis, are part of a large project [27] to analyze, systematically, balance ability and postural fluctuations in relation to age and gender.