Metabolic syndrome (MetS) is a complex interrelated risk factor for cardiovascular disease and type 2 diabetes mellitus. High cardiorespiratory fitness is known to contribute to prevention of MetS. However, little is known regarding the association between muscular fitness and MetS in Japanese adults. The purpose of this study was to examine the associations between muscular fitness and MetS in Japanese women and men. This cross-sectional study included 335 women and 209 men aged 30 - 79 y. MetS was determined according to the 2009 criteria of the International Diabetes Federation. Muscular fitness was evaluated by muscular fitness composite score (MFS), which was determined using Z scores from grip strength and sit-ups. Participants were classified by MFS tertile into low, middle, and high MFS groups. We used multiple logistic regression analysis to estimate odds ratios for the incidence of MetS in each group. The prevalence of MFS was 27.2% in women and 27.3% in men. Adjusted odds ratios for MetS prevalence in the low, middle, and high MFS groups, after adjusting for age, smoking status, alcohol intake, and exercise habits, were 1.0 (referent), 0.90 (95% confidence interval [CI], 0.50 - 1.62), and 0.49 (95% CI, 0.25 - 0.94; P for trend = 0.03) in women; in men, they were 1.0 (referent), 0.49 (0.23 - 1.04), and 0.42 (0.18 - 0.97; P for trend = 0.04), respectively. Muscular fitness is inversely associated with the prevalence of MetS in Japanese women and men.
Metabolic syndrome (MetS) is a clustering of central obesity and cardiovascular disease (CVD) risk factors, including abnormal blood pressure, lipids, and blood glucose [
The primary management approach for MetS is healthy lifestyle promotion such as increased physical activity and diet modification [
The subjects were 335 women and 209 men, aged 30 79 y, who underwent a baseline preventive medical examination and physical fitness tests between 2006 and 2010 and were recruited to participate in a training program for health promotion at Fujisawa City Health and Medical Center. All subjects provided written informed consent before enrollment in the study. This study was approved by the Ethics Committee of Waseda University and conducted in accordance with the spirit of the Declaration of Helsinki.
All subjects received preventive medical examinations at the medical institution in Fujisawa City The exam included a measurement of height, body weight, waist circumference (WC), blood chemistry analyses (triglycerides, TG; high-density lipoprotein, HDL-c; fasting blood glucose, FPG), and resting blood pressure (BP; systolic blood pressure, SBP; diastolic blood presser, DBP). Body mass index (BMI) was calculated as body weight (kg) divided by height squared (m2), and WC was measured at the umbilicus with subjects in the standing position.
MetS was defined as meeting 3 or more of the following criteria [
Grip strength test, used as a proxy for overall strength [
Abdominal muscle endurance was evaluated by a situp test [
Muscular fitness was evaluated by muscular fitness composite score (MFS), which was determined using Z scores from grip strength and sit-ups.
Several confounding variables were included in the analyses: age (y), smoking status (current, former, never), daily alcohol intake (g/day), and exercise habits (never, once/wk, 2 - 3 times/wk, 4 - 5 times/wk, 6 - 7 times/wk). These variables were assessed by means of a questionnaire.
Measured and calculated values are presented as mean ± SD or number (%). Participants were classified by MFS tertile into low, middle, and high MFS groups. Analysis of variance was used for continuous variables with a normal distribution, the Kruskal-Wallis test was used for continuous variables with a non-normal distribution, and the chi-square test was used for categorical variables. The association of muscular fitness with the risk of having MetS was estimated using multiple logistic regression analysis adjusted for age (Model 1), and further adjusted for smoking status, alcohol intake, and exercise habits (Model 2). The data were analyzed with SPSS 19.0 for Windows (IBM Japan, Tokyo, Japan). The statistical significance level was set at P < 0.05.
Adjusted odds ratios (ORs) for MetS prevalence in the low, middle, and high MFS groups, after adjusting for age, were 1.0 (referent), 0.92 (95% confidence interval [CI]: 0.51 - 1.63), and 0.53 (95% CI, 0.28 - 0.99) (P for trend = 0.04) in women; in men, they were 1.0 (referent), 0.48 (95% CI, 0.23 - 1.01), and 0.42 (95% CI, 0.19 - 0.90) (P for trend = 0.02), respectively (