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Purpose: Arterial stiffness is considered a predictor of cardiovascular disease. Females have higher values of arterial stiffness than males, suggesting a greater risk of heart-related complications. Although a low-calorie diet (LCD) reduces fasting arterial stiffness, in part through weight loss, it is unknown if interval exercise (INT) adds to the benefit of LCD on fasting and postprandial arterial stiffness in females with obesity., Methods: Twenty-five females (47 ± 2.6 yr, 37.6 ± 1.3 kg·m-2) were randomized to 13 d of LCD (n = 12; mixed meals of ~1200 kcal·d-1) or LCD + INT (n = 13; 60 min·d-1 of supervised 3-min intervals at 90% HRpeak and 50% HRpeak). Arterial stiffness (augmentation index [AIx] and carotid-femoral pulse wave velocity [cfPWV]) and blood biochemistries were measured during a 75-g oral glucose tolerance test before and after the intervention to determine fasting and postprandial arterial stiffness as well as insulin sensitivity (simple index of insulin sensitivity [SIIS]) and inflammation (C-reactive protein, interleukin 8, and tumor necrosis factor alpha)., Results: Although LCD + INT increased V˙O2peak and HDL compared with LCD (P = 0.04 and P < 0.01, respectively), both interventions decreased body fat, LDL, total cholesterol, and triglycerides (all P < 0.01) and increased SIIS (P = 0.03). Despite no effect on fasting AIx (P = 0.27), LCD and LCD + INT decreased AIx60min (-7.4% ± 4.3% vs -7.0% ± 5.0%, P = 0.04) and tAUC120min (-663 ± 263 vs -457 ± 406, P = 0.03). There were no changes in fasting cfPWV (P = 0.91) or cfPWV120min (P = 0.62). Increased SIIS and decreased interleukin 8 were associated with reduced fasting AIx (r = -0.44, P = 0.03, and r = 0.40, P = 0.055), whereas decreased C-reactive protein correlated with reduced postprandial AIx60min (r = 0.43, P = 0.04)., Conclusion: Independent of exercise, 13 d of LCD reduces postprandial AIx in females with obesity. Insulin sensitivity and inflammation correlated with improved arterial stiffness, suggesting unique mechanisms regulate fasted versus postprandial arterial stiffness., (Copyright © 2020 by the American College of Sports Medicine.)

Background: Extracellular vesicles (EV) are purported to mediate type 2 diabetes and CVD risk and development. Physical activity and a balanced diet reduce disease risk, but no study has tested the hypothesis that short-term interval (INT) training would reduce EV compared with continuous (CONT) exercise in adults with prediabetes., Methods: Eighteen obese adults (age, 63.8 ± 1.5 yr; body mass index, 31.0 ± 1.3 kg·m) were screened for prediabetes using American Diabetes Association criteria (75 g oral glucose tolerance test). Subjects were randomized to INT (n = 10, alternating 3-min intervals at 90% and 50% HRpeak, respectively) or CONT (n = 8, 70% HRpeak) training for 12 supervised sessions over 13 d for 60 min·d. Cardiorespiratory fitness (V˙ O2peak), weight (kg), as well as ad libitum dietary intake were assessed and arterial stiffness (augmentation index via applanation tonometry) was calculated using total AUC during a 75-g oral glucose tolerance test performed 24 h after the last exercise bout. Total EV, platelet EV (CD31/CD41), endothelial EV (CD105; CD31/ CD41), platelet endothelial cell adhesion molecule (PECAM) (CD31), and leukocyte EV (CD45; CD45/CD41) were analyzed via imaging flow cytometry preintervention/postintervention., Results: The INT exercise increased V˙O2peak (P = 0.04) compared with CONT training. Although training had no effect on platelet or leukocyte EV, INT decreased Annexin V- endothelial EV CD105 compared with CONT (P = 0.04). However, after accounting for dietary sugar intake, the intensity effect was lost (P = 0.18). Increased ad libitum dietary sugar intake after training was linked to elevated AV+ CD105 (r = 0.49, P = 0.06) and AV- CD45 (r = 0.59, P = 0.01). Nonetheless, increased V˙O2peak correlated with decreased AV+ CD105 (r = -0.60, P = 0.01)., Conclusions: Interval exercise training decreases endothelial-derived EV in adults with prediabetes. Although increased sugar consumption may alter EV after a short-term exercise intervention, fitness modifies EV count.

Purpose: The optimal short-term exercise dose to improve glucose tolerance in relation to metabolic flexibility and/or insulin resistance is unknown. Therefore, we tested if short-term, work-matched continuous (CONT) versus interval (INT) exercise training improves glucose tolerance in part by reducing insulin resistance and increasing metabolic flexibility independent of clinically meaningful fat loss in adults with prediabetes., Methods: Subjects (age = 60.9 ± 1.4 yr, body mass index = 33.5 ± 1.1 kg·m) were screened for prediabetes using the American Diabetes Association criteria (75 g oral glucose tolerance test [OGTT] and/or HbA1c) and were randomized to 60 min·d of supervised CONT (n = 17, 70% HRpeak) or work-matched INT (n = 14; 90% HRpeak for 3 min and 50% HRpeak for 3 min) exercise for 12 bouts. Fitness (V˙O2peak) and body composition were assessed pre- and postintervention. A 180-min 75-g OGTT was performed, and glucose, insulin, and free fatty acids were collected to calculate glucose tolerance (tAUC180min) and whole-body as well as adipose tissue insulin resistance pre- and postintervention. RER (indirect calorimetry) was also measured at 0, 60, 120, and 180 min of the OGTT to assess fasting and postprandial metabolic flexibility., Results: CONT and INT training improved V˙O2peak (L·min; P = 0.001) and glucose tolerance (P = 0.01) and reduced fasting RER (P = 0.006), as well as whole-body and adipose insulin resistance (both P = 0.02) with no effect on body fat (P = 0.18). Increased postprandial RER was correlated with reduced glucose tAUC180min (r = -0.38, P = 0.05) and increased 180-min RER related to decreased whole-body insulin resistance (r = -0.42, P = 0.03)., Conclusion: Independent of exercise dose and fat loss, short-term training improves glucose tolerance in relation to enhanced postprandial fuel use.