Studies found that cardiovascular responses to exercise are enhanced in individuals with obesity and are associated with a greater cardiac output (CO) response compared to normal weight controls. However, the mechanisms underlying these altered responses during dynamic exercise are not clear. We investigated whether the cardiovascular responses mediated by the muscle metaboreflex (MMR) activation are augmented in obese men during both static and dynamic exercise. Twenty males (10 obese (OG) and 10 non-obese (NOG)) were studied. Changes in CO, mean arterial pressure (MAP), and total vascular conductance (TVC) were compared between the two groups during dynamic handgrip exercise (DHE), post-exercise muscular ischemia (PEMI), and dynamic exercise corresponding to 40%, 60% and 80% workloads. Subjects completed 2 min of DHE at 30% of MVC, followed by 2 min of PEMI. MAP, CO, and TVC responses to DHE and dynamic exercise were significantly higher in OG, whereas there were no differences during PEMI. Increases in CO and MAP during mild to heavy dynamic exercise were seen in both groups, but the changes in these variables were greater in the OG. There were no significant differences in TVC between the two groups. Compared to NOG, the augmented blood pressure response to DHE and dynamic exercise in OG was associated with a greater increase in CO. Thus, the augmented CO and MAP responses were not associated with the activation of the MMR. Consequently, additional factors specific to obesity, such as the mechanoreflex, may have been involved.

While dietary polyphenols supplements can improve endothelial function and blood flow to exercise, the effects of chronic supplementation with grape seed extract (GSE) containing a high dose of polyphenols on endurance performance are not known. Accordingly, in 12 elite athletes, we compared the effects of both GSE and placebo (PL) on submaximal VO₂, time to exhaustion performance, and endothelial function during progressive cycling exercise for 14 days. Endothelial function was evaluated from the brachial artery via flow-mediated dilation (FMD). Compared to PL, GSE decreased submaximal VO₂ at 80% and 120% of VO_2peak and increased the time to exhaustion (p < 0.05). GSE also resulted in FMD-induced increase in brachial artery diameter (14.4 ± 5.2% vs. 17.6 ± 4.5%, p = 0.035). We demonstrated that chronic supplementation with GSE improved endurance performance and these effects may partially be due to vasodilation in active skeletal muscle mediated by enhanced endothelial function. Thus, our results suggest that GSE appears to be an ergogenic nutraceutical that can improve exercise performance in elite athletes.

As the competition among businesses intensifies and customer needs become increasingly diverse and complex, the need for personalized service has emerged. This study examines the effect of technology-based self-service (TBSS) characteristics of a Taekwondo academy on perceived value and intention to use continuously. The study sample consisted of masters managing a Taekwondo academy who had prior experience with TBSS. A total of 188 responses were collected using an online questionnaire. The collected data were analyzed using SPSS 23.0 and AMOS 23.0. The results demonstrated the following: first, among the sub-factors of TBSS characteristics, reliability, usefulness, and enjoyment were found to affect the perceived value positively; second, among the sub-factors of TBSS characteristics, usefulness and ease of use positively affected the intention to use continuously; and finally, the perceived value was found to affect the intention to use continuously positively. This study provides practical implications for more efficient use of the TBSS provided by a Taekwondo academy by discovering the relationship between the TBSS configuration of the Taekwondo academy, perceived value, and intention to use continuously.