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PLoS One. 2014 Nov 26;9(11):e113646. doi: 10.1371/journal.pone.0113646. eCollection 2014.

Sex differences in flexibility-arterial stiffness relationship and its application for diagnosis of arterial stiffening: a cross-sectional observational study.

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Faculty of Engineering, Osaka Institute of Technology, Osaka, Japan.
Faculty of Business, Sports Management Course, Hannan University, Osaka, Japan.
Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan.
Faculty of Environmental Symbiotic Sciences, Prefectural University of Kumamoto, Kumamoto, Japan.



Arterial stiffness might be related to trunk flexibility in middle-aged and older participants, but it is also affected by age, sex, and blood pressure. This cross-sectional observational study investigated whether trunk flexibility is related to arterial stiffness after considering the major confounding factors of age, sex, and blood pressure. We further investigated whether a simple diagnostic test of flexibility could be helpful to screen for increased arterial stiffening.


According to age and sex, we assigned 1150 adults (male, n = 536; female, n = 614; age, 18-89 y) to groups with either high- or poor-flexibility based on the sit-and-reach test. Arterial stiffness was assessed by cardio-ankle vascular index.


In all categories of men and in older women, arterial stiffness was higher in poor-flexibility than in high-flexibility (P<0.05). This difference remained significant after normalizing arterial stiffness for confounding factors such as blood pressure, but it was not found among young and middle-aged women. Stepwise multiple-regression analysis also supported the notion of the sex differences in flexibility-arterial stiffness relationship. Receiver operating characteristic curve analysis revealed that cut-off values for sit-and-reach among men and women were 33.2 (area under the curve [AUC], 0.711; 95% confidence interval [CI], 0.666-0.756; sensitivity, 61.7%; specificity, 69.7%) and 39.2 (AUC, 0.639; 95% CI, 0.592-0.686; sensitivity, 61.1%; specificity, 62.0%) cm, respectively.


Our results indicate that flexibility-arterial stiffness relationship is not affected by BP, which is a major confounding factor. In addition, sex differences are observed in this relationship; poor trunk flexibility increases arterial stiffness in young, middle-aged, and older men, whereas the relationship in women is found only in the elderly. Also, the sit-and-reach test can offer a simple method of predicting arterial stiffness at home or elsewhere.

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