Abstract
According to the annual reports of physical fitness and motor ability by Ministry of Education, Science and Culture, children and youth have been improving consistently in the anthropometric measures since the survey of this kind initiated but lowering consistently in flexibility since first half of 1970s. The following criticism was reported; such lowering trend of flexibility has been caused by the measuring procedure of flexibility and not reflected by substantial deterioration of flexibility. It is true that the measuring method used in the survey is actually influenced by body linearity; stature, lower limb length and sitting height and so on, because the distance in trunk flexion and extenstion are measured. Then, in this paper, the annual changing trend of flexibility was estimated with the annual increase of stature taken into consideration under the assumption of linearity, and this estimated trends were compared with the actual annual changing trends of flexibility. All grades of the estimated annual trends in trunk flexion were found negative and significantly smaller in absolute value than the actual ones, so it was concluded that the actual deterioration trends can be explained partly by the increase of stature but the substantial deterioration also has appeared in flexibility. Furthermore, the body linearity elements would relate positively with trunk extension measures, but most of the grades were negative for trunk extension. This suggests also that the substantial deterioration has appeared in flexibility.
