Zhen Bo Cao

Predicting VO2max with an objectively measured physical activity in Japanese women.

PURPOSE To investigate the use of the accelerometer-determined physical activity (PA) intensity variables as the objective PA variables for estimating VO2max in Japanese adult women. METHODS The subjects of this study were 148 Japanese women aged 20 to 69 yr. Maximal oxygen uptake (VO2max) was measured with a maximal incremental test on a bicycle ergometer. Daily step counts (SC) and the amount spent in moderate to vigorous PA (MVPA) and vigorous PA (VPA) were measured using accelerometer-based activity monitors for 7 consecutive days. Using data of age, SC, MVPA, or VPA, and either body mass index (BMI) or waist circumference (WC), the nonexercise VO2max prediction models were derived as BMI models(MVPA), WC models(MVPA), BMI models(VPA), and WC models(VPA), and cross-validated by using two separate cross-validation procedures. RESULTS SC, MVPA, and VPA were significantly related to VO2max (r = 0.43, r = 0.52, and r = 0.58, respectively). The multiple correlation coefficients for the BMI and WC models(MVAP) were 0.83 and 0.85, respectively, and for the BMI and WC models(VPA), they were 0.85 and 0.86, respectively. The SEE was 3.3 and 3.1 mL x kg(-1) x min(-1) for the BMI and WC models(MVPA), respectively, and it was 3.1 and 3.0 mL x kg(-1) x min(-1) for the BMI and WC models(VPA), respectively. All regression models demonstrated a high level of cross-validity supported by the minor shrinkage of the coefficient of determination and the increment of SEE in the predicted residual sum of squares procedure, and by small constant errors for the subgroups of age, SC, and VO2max between 25 and 35 mL x kg(-1) x min(-1). CONCLUSIONS This study demonstrated that multiple regression models using data of MVPA or VPA were useful in predicting VO2max for Japanese adult women.

Common single nucleotide polymorphisms in the FNDC5 gene are associated with glucose metabolism but do not affect serum irisin levels in Japanese men with low fitness levels

OBJECTIVE This cross-sectional study analyzed the association of serum irisin concentrations with cardiorespiratory fitness levels and common single nucleotide polymorphisms (SNPs) in the FNDC5 gene and examined the relationships between cardiorespiratory fitness levels, common SNPs in FNDC5, and glucose metabolism. MATERIALS/METHODS Cardiorespiratory fitness was assessed by measuring peak oxygen uptake (VO2peak) and serum irisin levels by ELISA in 163 Japanese men (age, 21-79years). Subjects were divided into low- and high-fitness groups within each age group according to the median VO2peak value. Common SNPs (rs3480 and rs16835198) of the FNDC5 gene were genotyped with the TaqMan assay. Glucose metabolism was evaluated by measuring HbA1c, fasting plasma glucose (FPG), insulin levels, and HOMA-IR. RESULTS Serum irisin levels were negatively correlated with age (p<0.001) and not associated with the VO2peak or HOMA-IR. In the low-fitness group, SNP analysis revealed that subjects with the rs3480 AG and GG genotypes had higher levels of insulin and HOMA-IR than those with the AA genotype (p<0.01; no significant difference was observed in the high-fitness group). The GG genotypes of rs16835198 were associated with increased HbA1c and FPG in the low-fitness group only (p<0.05). SNPs and both fitness groups were not associated with serum irisin levels. CONCLUSIONS In Japanese men, cardiorespiratory fitness levels and common SNPs in FNDC5 are not associated with circulating irisin levels, whereas high cardiorespiratory fitness abolishes the association between the rs3480 and rs16835198 SNPs and glucose metabolism independent of serum irisin levels.

Association between Serum 25-Hydroxyvitamin D and Inflammatory Cytokines in Healthy Adults

Here, we aimed to examine the associations between levels of serum 25-hydroxyvitamin D [25(OH)D] and inflammatory cytokines in healthy Japanese adults. A total of 95 healthy adults (61 women; age range 21–69 years) participated in our study. Fasting blood samples were analyzed for 25(OH)D, 1,25-dihydroxyvitamin D [1,25(OH)2D], interferon-γ (IFN-γ), interleukin-6 (IL-6), and interleukin-17 (IL-17) levels using enzyme-linked immunosorbent assays kits. Total percent body fat was determined by dual energy X-ray absorptiometry (DXA). Moderate to vigorous physical activity (MVPA) was assessed objectively using an activity monitor for 7 days. The mean 25(OH)D concentration was 34.7 nmol/L, and 83 subjects had 25(OH)D concentrations less than 50 nmol/L. Multiple linear regression analysis revealed that serum 25(OH)D level was positively related to plasma IL-17 level (β = 0.26, p = 0.025), after adjustment for gender, age, vitamin D intake, alcohol consumption, smoking status, and percent body fat. This relationship remained statistically significant (β = 0.28, p = 0.019) even after additional adjustment for MVPA. However, no significant association was found between serum 25(OH)D level and plasma IFN-γ or IL-6 levels. In conclusion, this study identified a high prevalence of vitamin D deficiency in healthy Japanese adults. Serum 25(OH)D level was positively related to IL-17 level, independent of physical activity.

Associations between the Serum 25(OH)D Concentration and Lipid Profiles in Japanese Men

AIM Low circulating 25-hydroxyvitamin D [25(OH)D] concentration has been linked to a high prevalence of cardiovascular disease. One explanation for this phenomenon is that there is an association between the serum 25(OH)D level and lipid profiles. However, studies examining this relationship are limited and have yielded inconsistent results. We thus aimed to evaluate the association between the serum 25(OH)D concentration and lipid profiles in Japanese men taking into consideration confounding factors, including the visceral fat area (VFA) and cardiorespiratory fitness. METHODS A total of 136 men (age range: 20-79 years) participated in our study. Fasting blood samples were analyzed to determine the 25(OH)D, oxidized low-density lipoprotein (oxLDL), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), triglyceride (TG), apolipoprotein (Apo)A-1 and ApoB levels. The VFA was evaluated on magnetic resonance imaging (MRI), and cardiorespiratory fitness was assessed by measuring the peak oxygen uptake (VO2 peak). RESULTS The median 25(OH)D concentration was 35.6 nmol/L, and the prevalence of 25(OH)D deficiency was 78.7%. A multiple linear regression analysis revealed that the serum 25(OH)D concentration was inversely related to the LDL-C/HDL-C, TG, ApoB and ApoB/ApoA-1 values, even after adjusting for age, season, smoking status, alcohol consumption, medication use, vitamin D intake, calcium intake, VFA and cardiorespiratory fitness. CONCLUSIONS Serum 25(OH)D level is inversely correlated with the LDL-C/HDL-C, TG, ApoB and ApoB/ApoA-1 values in Japanese men, independent of the VFA and cardiorespiratory fitness.

Vitamin D supplementation reduces insulin resistance in Japanese adults: a secondary analysis of a double-blind, randomized, placebo-controlled trial

Higher circulating 25-hydroxyvitamin D (25[OH]D) concentration has been linked to a lower prevalence of insulin resistance and type 2 diabetes mellitus. However, randomized controlled trials have not clarified the effect of vitamin D supplementation on insulin resistance in healthy adults. The objective of this study was to assess the effect of vitamin D supplementation for 1 year on insulin resistance; the study was a secondary analysis of a clinical trial. We hypothesized that increased 25(OH)D concentration after vitamin D supplementation for 1 year would significantly improve insulin resistance. Ninety-six healthy adults participated in this study, of whom 81 completed the study. The participants randomly received daily either 420 IU vitamin D3 or placebo in a double-blind manner for 1 year. The levels of fasting insulin, glucose, and other parameters were assessed at baseline and after 1 year of intervention. Homeostasis model assessment of insulin resistance index was calculated from insulin and glucose levels. Visceral fat area and physical activity were also investigated. Serum 25(OH)D and 1,25-dihydroxyvitamin D concentrations were significantly increased by approximately 29.5 nmol/L and 7.0 pg/mL, respectively, after 1-year vitamin D supplementation. After vitamin D supplementation, fasting glucose levels and values of homeostasis model assessment of insulin resistance index significantly decreased from 88.3 to 85.3 mg/dL (P < .01) and 1.17 to 0.84 (P < .01), respectively, and the results were independent of physical activity and visceral fat accumulation. In conclusion, the present study showed that vitamin D supplementation for 1 year effectively improves fasting glucose level and insulin resistance in healthy Japanese adults.

Cardiorespiratory Fitness and Visceral Fat Are Key Determinants of Serum Fibroblast Growth Factor 21 Concentration in Japanese Men

CONTEXT Fibroblast growth factor-21 (FGF21) is an important metabolic regulator suggested to improve glucose metabolism and prevent dyslipidemia. An FGF21-resistant state that increases circulating FGF21 has been reported in obese patients. Although regular exercise prevents metabolic disease, the relationship of the fitness level to serum FGF21 level and body fat distribution in humans remains poorly understood. OBJECTIVE The objective of the study was to determine the relationship among the serum FGF21 concentration, cardiorespiratory fitness (CRF) level, and visceral fat area (VFA). DESIGN Serum FGF21 was measured by an ELISA in 166 middle-aged and elderly Japanese men (aged 30-79 y) and 25 untrained and 21 endurance-trained young men (aged 19-29 y). CRF was assessed by measuring the peak oxygen uptake (VO2peak) and VFA by magnetic resonance imaging. RESULTS In the middle-aged and elderly subjects, the serum FGF21 level correlated with the VO2peak (r = -0.355, P < .001) and VFA (r = 0.487, P < .001). Stepwise multiple regression analysis showed VFA to be most strongly associated with the serum FGF21 level (β = .360, P < .001), and VO2peak was also an independent predictor of the serum FGF21 level (β = -.174, P = .019). Furthermore, the proportion of subjects with an FGF21 level below the limit of detection was significantly higher among the endurance-trained than among the untrained young men (71.4% vs 24.0%, P = .001), and the VO2peak and VFA were independently associated with an undetectable FGF21 level (P < .05). CONCLUSIONS CRF and VFA are key determinants of the circulating FGF21 concentration.

Physical activity, exercise, sedentary behavior and health

Current Status of Physical Activity and Sedentary Behavior Research.- Physical activity levels and physical activity recommendation in Japanese.- Physical activity and sedentary behavior research: a European perspective.- Physical activity, sedentary behavior, and environment.- Measurement of physical activity.- Population strategy for physical activity promotion.- Promotion of muscular-strengthening activity Health impacts of light intensity physical activity.- Sedentary behavior and cardiometabolic health.- Transportation, sitting and community health.- Occupational sitting and worksite health promotion.- Public health hazard of prolonged leisure time TV viewing.- Effects of Physical Activity, Exercise, Fitness on the Human Organism.- Autonomic and endocrine functions in response to exercise.- Autonomic functions and artery stiffness repose to stretching exercise.- Habitual resistance and aerobic training and central arterial functions.- Appetite responses to acute exercise Chronic exercise and appetite.- Exercise and hormonal regulation of appetite.- Role of exercise on postprandial plasma glucose response to high-fat intake.- Posttranslational modification of proteins in aging: impact of exercise.- Cardiorespiratory fitness and peroxisome proliferator-activated receptor-gamma2 genotypes to the metabolic syndrome.- Vasopressin V1a receptor polymorphism and adherence to long-term interval walking training.- Exercise and ss2-Adrenergic Receptor Expression.- Physical Activity, Exercise, Nutrition, Aging and Health.- The role of exercise and nutrition in lifestyle-related disease.- Physical activity in the prevention of atherosclerosis.- Physical activity, exercise, and sleep.- Physical activity, exercise, and immunity.- Physical activity, nutrition, and bone health.- Physical activity, exercise and musculoskeletal health in older adults.- Dog walking: an effective strategy for physical activity promotion.- Effective exercise programs among frail elderly.- Rowing: a favorable tool of both aerobic and resistance exercises for health promotion in elderly people.- Roles of physical activity for older adults: Maximizing brain plasticity with physical exercise.- Sensory perception and physical function in elderly people.

Does Cardiorespiratory Fitness Modify the Association between Birth Weight and Insulin Resistance in Adult Life

Objective Lower birth weight is associated with higher insulin resistance in later life. The aim of this study was to determine whether cardiorespiratory fitness modifies the association of birth weight with insulin resistance in adults. Methods The subjects were 379 Japanese individuals (137 males, 242 females) aged 20–64 years born after 1943. Insulin resistance was assessed using a homeostasis model assessment of insulin resistance (HOMA-IR), which is calculated from fasting blood glucose and insulin levels. Cardiorespiratory fitness (maximal oxygen uptake, VO2max) was assessed by a maximal graded exercise test on a cycle ergometer. Birth weight was reported according to the Maternal and Child Health Handbook records or the subject’s or his/her mother’s memory. Results The multiple linear regression analysis revealed that birth weight was inversely associated with HOMA-IR (β = −0.141, p = 0.003), even after adjustment for gender, age, current body mass index, mean blood pressure, triglycerides, HDL cholesterol, and smoking status. Further adjustments for VO2max made little difference in the relationship between birth weight and HOMA-IR (β = −0.148, p = 0.001), although VO2max (β = −0.376, p<0.001) was a stronger predictor of HOMA-IR than birth weight. Conclusions The results showed that the association of lower birth weight with higher insulin resistance was little modified by cardiorespiratory fitness in adult life. However, cardiorespiratory fitness was found to be a stronger predictor of insulin resistance than was birth weight, suggesting that increasing cardiorespiratory fitness may have a much more important role in preventing insulin resistance than an individual’s low birth weight.

Cardiorespiratory Fitness is a Strong Predictor of the Cardio-ankle Vascular Index in Hypertensive Middle-aged and Elderly Japanese Men

AIM This study aimed to examine whether cardiorespiratory fitness (CRF) is associated with arterial stiffening, evaluated using the cardio-ankle vascular index (CAVI), independent of visceral fat (VF) in middle-aged and elderly Japanese men. We also examined whether the relationship between CRF and the CAVI is modified by age and/or hypertension. METHODS The CAVI was determined in 157 Japanese men (age range, 30-79 years), including 96 hypertensive subjects (61.1%). CRF was assessed by measuring the peak oxygen uptake (VO2peak). The subjects were divided into low- and high-CRF groups, and the VF area was assessed using magnetic resonance imaging. RESULTS The VO2peak correlated with the CAVI following adjustment for age and body mass index in the middle-aged and elderly groups (all the subjects: r=-0.285, p＜0.001; middle-aged: r=-0.240, p=0.040; elderly: r=-0.225, p=0.049). VF also correlated with the CAVI (r=0.230, p=0.004). A multiple linear regression analysis revealed that age (β=0.406, p<0.001) and the VO2peak (β=-0.186, p=0.015) were associated with the CAVI independently of VF and the mean blood pressure. Two way ANCOVA adjusted for age demonstrated that the hypertensive individuals had higher CAVI values than the normotensive individuals in the low-CRF group, whereas no significant differences in the CAVI were observed in the high-CRF group (p for interaction <0.05). CONCLUSIONS In the present study, CRF was found to be associated with the CAVI, independent of age and VF, in hypertensive middle-aged and elderly Japanese men.

Polygenic risk for hypertriglyceridemia is attenuated in Japanese men with high fitness levels.

High cardiorespiratory fitness (CRF) is associated with a reduced risk for dyslipidemia; however, blood lipid levels are also affected by individual genetic variations. We performed a cross-sectional study to determine whether CRF modifies polygenic risk for dyslipidemia. Serum levels of triglycerides (TG), LDL cholesterol (LDL-C), and HDL cholesterol (HDL-C) were measured in 170 Japanese men (age 20-79 yr). CRF was assessed by measuring maximal oxygen uptake (Vo2max), and subjects were divided into low-fitness and high-fitness groups according to the reference Vo2max value for health promotion in Japan. We analyzed 19 single nucleotide polymorphisms (SNPs) associated with TG, LDL-C, or HDL-C levels. Based on these SNPs, we calculated three genetic risk scores (GRSs: TG-GRS, LDL-GRS, and HDL-GRS), and subjects were divided into low, middle, and high groups according to the tertile for each GRS. Serum TG levels of low-fitness individuals were higher in the high and middle TG-GRS groups than in the low TG-GRS group (P < 0.01 and P < 0.05, respectively), whereas no differences were detected in the TG levels of high-fitness individuals among the TG-GRS groups. In contrast, the high LDL-GRS group had higher LDL-C levels than did the low LDL-GRS group, and HDL-C levels were lower in the high HDL-GRS group than in the low HDL-GRS group regardless of the fitness level (P < 0.05). These results suggest that high CRF attenuates polygenic risk for hypertriglyceridemia; however, high CRF may not modify the polygenic risk associated with high LDL-C and low HDL-C levels in Japanese men.