Vigorous-intensity exercise as a modulator of cardiac adipose tissue in women with obesity: a cross-sectional and randomized pilot study.

Cardiac adipose tissue (CAT) has become an important target for the reduction of disease risk. Supervised exercise programs have shown potential to "significantly" reduce CAT; however, the impact of different exercise modalities is not clear, and the relationships between CAT, physical activity (PA) levels and fitness (PFit) remain unknown. Therefore, the purpose of this study was to analyze the relationships between CAT, PA and PFit, and to explore the effects of different exercise modalities in a group of women with obesity. A total of 26 women (age: 23.41 ± 5.78 years-old) were enrolled in the cross-sectional study. PA, cardiorespiratory fitness, muscular strength, body composition and CAT were evaluated. The pilot intervention included 16 women randomized to a control (CON, n=5), high intensity interval training (HIIT, n = 5) and high-intensity circuit training (HICT, n=6) groups. Statistical analysis showed negative correlations between CAT and vigorous PA (VPA) (r s=-0.41, p=0.037); and between percent body fat (%BF), fat mass (FM), and all PA levels (r s=-0.41- -0.68, p<0.05); while muscle mass was positively associated with moderate-to-vigorous PA, and upper-body lean mass with all PA levels (r s =0.40-0.53, p<0.05). The HICT intervention showed significant improvements (p<0.05) in %BF, FM, fat free mass, and whole-body and lower extremities lean mass and strength after three weeks; however, only leg strength and upper extremities' FM improved significantly compared to CON and HICT. In conclusion, although all types of PA showed a positive influence on body fat content, only VPA significantly impacted on CAT volume. Moreover, three weeks of HICT induced positive changes in PFit in women with obesity. Further research is needed to explore VPA levels and high-intensity exercise interventions for short- and long-term CAT management.

Development and evaluation of a method for segmentation of cardiac, subcutaneous, and visceral adipose tissue from Dixon magnetic resonance images.

Magnetic resonance imaging (MRI) has evolved into the gold standard for quantifying excess adiposity, but reliable, efficient use in longitudinal studies requires analysis of large numbers of images. The objective of this study is to develop and evaluate a segmentation method designed to identify cardiac, subcutaneous, and visceral adipose tissue (VAT) in Dixon MRI scans. The proposed method is evaluated using 10 scans from volunteer females 18- to 35-years old, with body mass indexes between 30 and 39.99 kg / m 2 . Cross-sectional area (CSA) for cardiac adipose tissue (CAT), subcutaneous adipose tissue (SAT), and VAT, is compared to manually-traced results from three observers. Comparisons of CSA are made in 191 images for CAT, 394 images for SAT, and 50 images for VAT. The segmentation correlated well with respect to average observer CSA with Pearson correlation coefficient ( R 2 ) values of 0.80 for CAT, 0.99 for SAT, and 0.99 for VAT. The proposed method provides accurate segmentation of CAT, SAT, and VAT and provides an option to support longitudinal studies of obesity intervention.

ß-Hydroxy ß-methylbutyrate free acid alters cortisol responses, but not myofibrillar proteolysis, during a 24-h fast.

This study was a randomised, double-blind, placebo-controlled cross-over trial examining the effects of ß-hydroxy ß-methylbutyrate free acid (HMB-FA) supplementation on muscle protein breakdown, cortisol, testosterone and resting energy expenditure (REE) during acute fasting. Conditions consisted of supplementation with 3 g/d HMB-FA or placebo during a 3-d meat-free diet followed by a 24-h fast. Urine was collected before and during the 24-h fast for analysis of 3-methylhistidine:creatinine ratio (3MH:CR). Salivary cortisol, testosterone, their ratio (T:C), and the cortisol awakening response were assessed. ANOVA was used to analyse all dependent variables, and linear mixed models were used to confirm the absence of carryover effects. Eleven participants (six females, five males) completed the study. Urinary HMB concentrations confirmed compliance with supplementation. 3MH:CR was unaffected by fasting and supplementation, but the cortisol awakening response differed between conditions. In both conditions, cortisol increased from awakening to 30 min post-awakening (P=0·01). Cortisol was reduced from 30 to 45 min post-awakening with HMB-FA (-32 %, d=-1·0, P=0·04), but not placebo (PL) (-6 %, d=-0·2, P=0·14). In males, T:C increased from 0 to 24 h of fasting with HMB-FA (+162 %, d=3·0, P=0·001), but not placebo (+13 %, d=0·4, P=0·60), due to reductions in cortisol. REE was higher at 24 h of fasting than 16 h of fasting independent of supplementation (+4·0 %, d=0·3, P=0·04). In conclusion, HMB-FA may affect cortisol responses, but not myofibrillar proteolysis, during acute 24-h fasting.