Differences in cardiovascular function between sexes have been documented at rest and maximal exercise. The purpose of this study was to examine the sex differences in cardiovascular function during submaximal constant-load exercise, which is not well understood.Thirty-one male and 33 female subjects completed nine minutes moderate and nine minutes vigorous intensity submaximal exercise (40 and 75% of peak watts determined by maximal exercise test). Measurements included: intra-arterial blood pressure (SBP and DBP), cardiac index (Q_I), heart rate (HR), oxygen consumption (VO₂) and arterial catecholamines (epinephrine = EPI and norepinephrine = NE), and blood gases. Mean arterial pressure (MAP), stroke volume index (SV_I), systemic vascular resistance index (SVR_I), arterial oxygen content (CaO₂), arterial to venous O₂difference (AVO₂) and systemic oxygen transport (SOT) were calculated.At rest and during submaximal exercise Q_I, SV_I, SBP, MAP, NE, CaO₂, and SOT were lower in females compared to males. VO₂, AVO₂, EPI were lower in females throughout exercise. When corrected for wattage, females had a higher Q, HR, SV, VO₂and AVO₂despite lower energy expenditure and higher mechanical efficiency.This study demonstrates sex differences in the cardiovascular response to constant-load submaximal exercise. Specifically, females presented limitations in cardiac performance in which they are unable to compensate for reductions in stroke volume through increases in HR, potentially a consequence of a female’s blunted sympathetic response and higher vasodilatory state. Females demonstrated greater cardiac work needed to meet the same external work demand, and relied on increased peripheral oxygen extraction, lower energy expenditure and improvements in mechanical efficiency as compensatory mechanisms.

Impaired endothelial function has been implicated as an initial step in the pathogenesis of atherosclerosis leading to cardiovascular disease (CVD). Aerobic exercise improves vascular function and reduces risk of CVD morbidity and mortality; however, the effects of resistance training on vascular function remains unclear. Thus, the aim of this study was to examine the effects of 1 yr of resistance training (RT) on vascular structure and function in overweight but otherwise healthy eumenorrheic women. Study participants consisted of 30 (15 control, 15 RT) overweight (BMI > 25 kg x m(-2)) women, aged 24-44 yr, studied before and after a 1-yr RT intervention. Vascular structure and function were assessed via noninvasive ultrasound imaging of the carotid and brachial arteries, respectively. Body composition, blood pressure, and fasting blood lipids and glucose also were measured. The RT group demonstrated a significant mean improvement in one-repetition maximum bench press following 1 yr of RT (P < 0.05). There also was a significant increase in lean body mass in the RT group compared with the control group (P = 0.04). There were no training-associated changes in blood pressure, fasting blood lipids, glucose, or insulin levels. Although there was no change in carotid artery intimamedia thickness, peak flow-mediated dilation significantly improved in the RT group (P < 0.05). The principal significant finding in this study was the initial demonstration that RT alone can improve brachial artery endothelial function in overweight eumenorrheic women.

To examine the effect of high-intensity interval training (HIIT) on metabolic syndrome (MetS) and body composition in cardiac rehabilitation (CR) patients with myocardial infarction (MI). We retrospectively screened 174 consecutive patients with MetS enrolled in CR following MI between 2015 and 2018. We included 56 patients who completed 36 CR sessions and pre-post dual-energy X-ray absorptiometry. Of these patients, 42 engaged in HIIT and 14 in moderate-intensity continuous training (MICT). HIIT included 4–8 intervals of high-intensity (30–60 s at RPE 15–17 [Borg 6–20]) and low-intensity (1–5 min at RPE < 14), and MICT included 20–45 min of exercise at RPE 12–14. MetS and body composition variables were compared between MICT and HIIT groups. Compared to MICT, HIIT demonstrated greater reductions in MetS (relative risk = 0.5, 95% CI 0.33–0.75, P < .001), MetS z-score (− 3.6 ± 2.9 vs. − 0.8 ± 3.8, P < .001) and improved MetS components: waist circumference (− 3 ± 5 vs. 1 ± 5 cm, P = .01), fasting blood glucose (− 25.8 ± 34.8 vs. − 3.9 ± 25.8 mg/dl, P < .001), triglycerides (− 67.8 ± 86.7 vs. − 10.4 ± 105.3 mg/dl, P < .001), and diastolic blood pressure (− 7 ± 11 vs. 0 ± 13 mmHg, P = .001). HIIT group demonstrated greater reductions in body fat mass (− 2.1 ± 2.1 vs. 0 ± 2.2 kg, P = .002), with increased body lean mass (0.9 ± 1.9 vs. − 0.9 ± 3.2 kg, P = .01) than the MICT. After matching for exercise energy expenditure, HIIT-induced improvements persisted for MetS z-score (P < .001), MetS components (P < .05), body fat mass (P = .002), body fat (P = .01), and lean mass (P = .03). Our data suggest that, compared to MICT, supervised HIIT results in greater improvements in MetS and body composition in MI patients with MetS undergoing CR.