AZUMA, KOICHIRO, FUMINORI KATSUKAWA, SHUJI OGUCHI, MITSURU MURATA, HAJIME YAMAZAKI, AKIRA SHIMADA, AND TAKAO SARUTA. Correlation between serum resistin level and adiposity in obese individuals. Obes Res. 2003;11: 997-1001. Objective: Resistin is associated with insulin resistance in mice and may play a similar role in humans. The aim of our study was to examine the relationship of serum resistin level to body composition, insulin resistance, and related obesity phenotypes in humans. Research Methods and Procedures: Sixty-four young (age 32 Ϯ 10 years), obese (BMI 32.9 Ϯ 5.6), nondiabetic subjects taking no medication, and 15 lean (BMI 21.1 Ϯ 1.3) volunteers were studied cross-sectionally. Thirty-five of the subjects were also reevaluated after 1.5 years on a weight reduction program entailing dieting and exercise; changes of serum resistin were compared with changes of BMI, body composition, fat distribution, and several indices of insulin sensitivity derived from plasma glucose and serum insulin levels measured during 75-g oral glucose tolerance test. Results: In a cross-sectional analysis, serum resistin was significantly higher in obese subjects than in lean volunteers (24.58 Ϯ 12.93 ng/mL; n ϭ 64 vs. 12.83 Ϯ 8.30 ng/mL; n ϭ 15; p Ͻ 0.01), and there was a correlation between resistin level and BMI, when the two groups were combined ( ϭ 0.35, p Ͻ 0.01). Although cross-sectional analysis in obese subjects revealed no correlation between serum resistin and parameters related to adiposity or insulin resistance, longitudinal analysis revealed change in serum resistin to be positively correlated with changes in BMI, body fat, fat mass, visceral fat area, and mean glucose and insulin ( ϭ 0.39, 0.40, 0.44, 0.50, 0.40, and 0.50; p ϭ 0.02, 0.03, 0.02, Ͻ0.01, 0.02, and Ͻ0.01, respectively). Discussion: Resistin appears to be related to human adiposity and to be a possible candidate factor in human insulin resistance.

A meta-analysis was performed in order to test the hypothesis that Japanese have a greater amount of abdominal visceral fat (AVF) relative to abdominal subcutaneous fat (ASF) than Caucasians. Data were derived from published studies that included mean values for AVF and ASF areas, measured using computed tomography, and age for native Japanese, African-Americans, and Caucasians of both genders. Mean values from each study were used as single data points. A significant difference in AVF was observed between Japanese and Caucasian populations after adjusting for ASF, age, and sex ( p<0.05). However, the difference in AVF between Japanese and Caucasian females was lower than that between African-American and Caucasian females.

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We found that variability in the serum resistin level might be related to polymorphic variants of the promoter region of the gene.

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It is unclear whether combined leg and arm high-intensity interval training (HIIT) improves fitness and morphological characteristics equal to those of leg-based HIIT programs. The aim of this study was to compare the effects of HIIT using leg-cycling (LC) and arm-cranking (AC) ergometers with an HIIT program using only LC. Effects on aerobic capacity and skeletal muscle were analyzed. Twelve healthy male subjects were assigned into two groups. One performed LC-HIIT (n=7) and the other LC- and AC-HIIT (n=5) twice weekly for 16 weeks. The training programs consisted of eight to 12 sets of >90% VO2 (the oxygen uptake that can be utilized in one minute) peak for 60 seconds with a 60-second active rest period. VO2 peak, watt peak, and heart rate were measured during an LC incremental exercise test. The cross-sectional area (CSA) of trunk and thigh muscles as well as bone-free lean body mass were measured using magnetic resonance imaging and dual-energy X-ray absorptiometry. The watt peak increased from baseline in both the LC (23%±38%; P<0.05) and the LC–AC groups (11%±9%; P<0.05). The CSA of the quadriceps femoris muscles also increased from baseline in both the LC (11%±4%; P<0.05) and the LC–AC groups (5%±5%; P<0.05). In contrast, increases were observed in the CSA of musculus psoas major (9%±11%) and musculus anterolateral abdominal (7%±4%) only in the LC–AC group. These results suggest that a combined LC- and AC-HIIT program improves aerobic capacity and muscle hypertrophy in both leg and trunk muscles.

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Objective. The aim of this study was to evaluate the relationships between the composition of free fatty acids (FFAs) and metabolic parameters, including body fat distribution, in Japanese. Methods. The study subjects were 111 Japanese patients (54 males, 57 females). Metabolic parameters and visceral and subcutaneous fat areas as determined by CT scanning at the umbilical level were measured. Glucose tolerance test (GTT) was performed by administering 75 g glucose orally. Results. The percentage of linoleic acid (C18:2), the greatest constituent among FFAs, was negatively correlated with visceral fat area (r = −0.411, p < 0.0001), fasting glucose (r = −0.330, p < 0.0001), HbA1c (r = −0.231, p = 0.0146), and systolic blood pressure (r = −0.224, p = 0.0184). Linoleic acid percentage was also significantly negatively correlated with HOMA-IR (r = −0.416, p < 0.0001) by simple correlation. Based on the findings of OGTT, the 111 subjects were classified into three groups: 33 with normal glucose tolerance, 71 with impaired glucose tolerance (IGT), and 7 diabetic subjects. The percentage of serum linoleic acid in diabetic subjects was significantly lower than that in normal subjects. Conclusion. We conclude that serum linoleic acid level is negatively correlated with the accumulation of visceral fat in relation to a reduction of insulin resistance in Japanese subjects.