Izumi Tabata

A cross-sectional study of sarcopenia in Japanese men and women: reference values and association with cardiovascular risk factors.

In this study of Japanese men and women, we determine reference values for sarcopenia and test the hypothesis that sarcopenia is associated with risk factors for cardiovascular disease, independent of waist circumference. A total of 1,488 Japanese men and women aged 18–85xa0years participated in this study. Appendicular muscle mass (AMM) was measured by dual-energy X-ray absorptiometry. Reference values for classes 1 and 2 sarcopenia (skeletal muscle index: AMM/height2, kgxa0m−2) in each sex were defined as values one and two standard deviations below the sex-specific means of reference values obtained in this study from young adults aged 18–40xa0years. The reference values for class 1 and class 2 sarcopenia were 7.77 and 6.87xa0kgxa0m−2 in men and 6.12 and 5.46xa0kgxa0m−2 in women. In subjects both with class 1 and class 2 sarcopenia, body mass index and % body fat were significantly lower than in normal subjects. Despite whole-blood glycohaemoglobin A1c in men with class 1 sarcopenia was significantly higher than in normal subjects, and brachial-ankle pulse wave velocity in women both with class 1 and class 2 sarcopenia were significantly higher than in normal subjects, using one-way ANCOVA with adjustment for the covariate of waist circumference. Although sarcopenia is associated with thin body mass, it is associated with more glycation of serum proteins in men and with greater arterial stiffness in women, independent of waist circumference.

Age and cardiorespiratory fitness are associated with arterial stiffening and left ventricular remodelling

Arterial stiffening, hypertension and left ventricular (LV) remodelling are associated with increased risk of cardiovascular disease. Cardiorespiratory fitness is associated with cardiovascular function and reduced risk of cardiovascular disease. This cross-sectional study was carried out to determine the relationships between cardiorespiratory fitness, arterial stiffness, blood pressure (BP) and LV remodelling in women. On the basis of peak oxygen uptake, a total of 159 premenopausal (young) and postmenopausal (older) women were categorized into either low (unfit) or high (fit) cardiorespiratory fitness groups. The arterial stiffness and LV remodelling were measured by brachial-ankle pulse wave velocity (baPWV) and carotid augmentation index (AI) and LV relative wall thickness (RWT). Two-way analysis of variance indicated a significant interaction between age and cardiorespiratory fitness in baPWV, carotid AI, BP and RWT. In the older group, arterial stiffness (baPWV; 1401±231 vs 1250±125u2009cmu2009s–1, P<0.01, AI; 32.9±9.9 vs 24.8±10.1%, P<0.01), systolic blood pressure (SBP) (130±22 vs 117±15u2009mmu2009Hg, P<0.01) and RWT (0.47±0.08 vs 0.42±0.04, P<0.05) in fit women were lower than in unfit women. In older women, RWT was significantly related to baPWV (r=0.46, P<0.01), carotid AI (r=0.29, P<0.05), SBP (r=0.57, P<0.01) [Vdot ]2peak (r=−0.32, P<0.05). In young women, they were not significant correlations, except for a weak correlation between RWT and SBP (r=0.21, P<0.05). These results suggest that higher cardiorespiratory fitness is associated with lower arterial stiffness, BP and RWT in older women.

Muscle mass and bone mineral indices: does the normalized bone mineral content differ with age?

Objective:To investigate the relationships between regional skeletal muscle mass (SM mass) and bone mineral indices and to examine whether bone mineral content (BMC) normalized to SM mass shows a similar decrease with age in young through old age.Subjects/Methods:One hundred and thirty-eight young and postmenopausal women aged 20–76 years participated in this study and were divided into three groups: 61 young women, 49 middle-aged postmenopausal women and 28 older postmenopausal women. Muscle thickness (MTH) was determined by ultrasound, and regional SM mass (arm, trunk and leg) was estimated based on nine sites of MTH. Whole-body and regional lean soft tissue mass (LSTM), bone mineral density (BMD) and BMC (whole body, arms, legs and lumbar spine) were measured using dual-energy X-ray absorptiometry.Results:Ultrasound spectroscopy indicated that SM mass is significantly correlated with site-matched regional bone mineral indices and these relationships correspond to LSTM. The BMC and BMD in older women were significantly lower than those in middle-aged women. When BMC was normalized to site-matched regional SM mass, BMC normalized to SM mass in arm and trunk region were significantly different with age; however, whole-body and leg BMC normalized to SM mass showed no significant difference between middle-aged and older postmenopausal women.Conclusions:The age-related differences in BMC were found to be independent of the ageing of SM mass in the arm and trunk region. However, differences in BMC measures of the leg and whole body were found to correspond to age-related decline of SM mass in postmenopausal women.

Resting energy expenditure can be assessed by dual-energy X-ray absorptiometry in women regardless of age and fitness

Objective:To evaluate the possibility that measurement of the magnitude and distribution of fundamental somatic heat-producing units using dual-energy X-ray absorptiometry (DXA) can be used to estimate resting energy expenditure (REE) in both young and elderly women with different aerobic fitness levels.Subjects and methods:Peak oxygen uptake (VO2 peak) and REEm were directly measured in 116 young (age: 22.3±2.1 years) and 72 elderly (63.3±6.4 years) women. The subjects were divided into four groups according to categories of age and VO2 peak; young: high fitness (YH, n=58); low fitness (YL, n=58); elderly: high fitness (EH, n=37) and low fitness (EL, n=35). Using DXA, systemic and regional body compositions were measured, and REEe was estimated from the sum of tissue organ weights multiplied by corresponding metabolic rate.Results:Although there were remarkable differences in systemic and regional body compositions, no significant differences were observed between REEm and REEe in the four groups. REEe significantly correlated with REEm in elderly as well as young women; the slopes and intercepts of the two regression lines were statistically not different between the elderly and young groups (elderly: y=0.60x+472, r=0.667; young: y=0.78x+250, r=0.798; P<0.001, respectively). A Bland–Altman analysis did not indicate bias in calculation of REE for all the subjects.Conclusion:These results suggest that REE can be estimated from tissue organ components in women regardless of age and aerobic fitness.