ABSTRACT
Purpose@#Moderate-intensity continuous training (MICT) improves exercise capacity with vascular benefits, but time constraints hinder consistent adherence. High-intensity interval training (HIIT) has emerged as a time-efficient alternative, with repeated sprint training (RST) being the shortest format. We hypothesized that RST would be as effective as MICT in improving vascular function and exercise capacity in young adults. @*Methods@#Twenty-three adults (mean age, 26.2±3.8 years) were randomly assigned to either RST or MICT. RST involved 20 sets of 4-second cycling sprints followed by 30-second active recovery, totaling 11 minutes. MICT consisted of 30-minute cycling at 50% to 60% of heart rate reserve. Vascular function evaluated via brachial artery flow-mediated dilation. Exercise capacity (maximum oxygen uptake, total exercise load test time) and anaerobic capacity (maximum power, anaerobic threshold) were measured using maximum exercise tests. These variables were measured befre and after a 6-week training. @*Results@#Both groups showed comparable improvements in flow-mediated dilation (p＜ 0.05). Maximum oxygen intake slightly improved, while total exercise time significantly increased for both (p＜ 0.05). Anaerobic threshold unchanged, while maximum power improved (p＜ 0.05). @*Conclusion@#These findings underscore that RST is a time-efficient exercise strategy, which improves vascular function and exercise capacity as effectively as MICT in young adults.
ABSTRACT
Purpose@#Isometric handgrip exercise (IHE) has a favorable cardiovascular effect and improves hemodynamic responses. Whether IHE attenuates stress-related hemodynamic reactivity assessed during a sympathetic challenge remains unexplored. We tested the hypothesis that an acute bout of IHE would improve carotid arterial function and attenuate cardiovascular vasoreactivity response to sympathetic stress in healthy adults. @*Methods@#In a randomized cross-over design, sixteen healthy adults (aged 21.8±3.1 years) were enrolled. Participants completed two testing sessions, separated by 1 week. Trials were either a control trial or performed IHE for two sets of 2 minutes at 30% of maximal voluntary contraction for each hand. The participant’s hand was immersed in an ice water bath (4 ℃ ) up to the wrist for 2 minutes. Carotid artery diameter, β-stiffness index, and compliance using ultrasound machine and brachial blood pressure (BP), heart rate (HR) were measured as indices of vasoreactivity at baseline, during, and recovery from cold pressor testing (CPT). @*Results@#The BP, HR, carotid artery diameter, and β-stiffness index increased similarly during CPT in both trials (p＜ 0.001), without any interaction effect. Compared with the IHE trial, arterial compliance decreased in the control groups at 120 seconds during recovery with a significant interaction effect (p=0.02). @*Conclusion@#These findings suggest that an acute IHE did not attenuate BP, HR, carotid artery diameter and β-stiffness index vasoreactivity, but improved carotid artery compliance to sympathetic activation in healthy young adults.
ABSTRACT
Purpose@#Numerous studies have reported the effects of interrupting prolonged sitting with aerobic exercise on vascular and postprandial function, but the effects of resistance exercise for interrupting prolonged sitting remain unclear. We tested the hypothesis that intermittent resistance activity breaks would attenuate prolonged sittinginduced vascular and postprandial metabolic dysfunction. @*Methods@#Fourteen healthy adults (age, 24±2 years; body mass index, 22.0±2.4 kg/m2 ) completed two trials in a randomized cross-over design. During a 4-hour sitting after a high-fat meal, the participants underwent either resistance activity (RA) with 10 repetitions of five exercises every hour or uninterrupted sitting as a control trial (SIT). Plasma glucose, triglycerides, and brachial artery blood pressure, along with blood flow and shear rate in the superficial femoral artery and carotid artery were measured at baseline and every hour during the 4-hour sitting period. Brachial artery flow-mediated dilation (FMD) was measured at baseline, 2 hours, and 4 hours after the start of the sitting. @*Results@#Plasma glucose and triglycerides increased after a high-fat meal in both RA and SIT groups without a significant interaction effect. In addition, while SIT group decreased brachial artery FMD (7.2%±2.0% to 6.5%±2.7% to 5.1%±2.6%), RA did not attenuate a decrease in FMD (7.6%±3.4% to 7.3%±3.1% to 6.7%±2.7%, interaction p=0.581). @*Conclusion@#Our findings indicate that interrupting prolonged sitting with intermittent RA did not attenuate the negative effects of sitting on vascular function and postprandial metabolism in young healthy adults.