Comparison of high-intensity interval training and moderate-intensity continuous training on cardiopulmonary function, cardiac autonomic function and vascular function in adolescent boys with obesity: A randomized controlled trial.

Adolescent obesity can impair cardiopulmonary function, vascular elasticity, endothelial function, and vago-sympathetic balance. While moderate-intensity continuous training (MICT) benefits cardiovascular health in obese adolescents, the effects of high-intensity interval training (HIIT) are less understood. We hypothesize that HIIT may be more effective than MICT in improving VO2peak, vascular elasticity, endothelial function, and vago-sympathetic balance in obese adolescent boys. Forty four participants were randomly assigned to the HIIT (10 × 1-min at 85%-95% peak HR, intersperse with 2-min active recovery at 60%-70% peak HR) or MICT (35 min at 65%-75% peak HR) for an 8-week program. The primary outcome measured was the change in VO2peak with secondary outcomes including brachial-ankle pulse wave velocity (baPWV), flow-mediated dilation (FMD), and heart rate variability (HRV). Forty four adolescent boys with obesity (age, 14 ± 1 years old, body mass index, 31.6 ± 1.3 kg/m2) were enrolled and 43 (97.73%) completed the 8-week exercise. No significant difference of VO2peak was found between the HIIT and MICT group (p = 0.243). There was no significant difference of baPWV between the groups (p = 0.789). Change in FMD% was significantly higher in the HIIT group compared to the MICT group (p < 0.001). The Change in HRV-high frequency (HRV-HF; p = 0.009) and HRV-low frequency/high frequency (HRV-LF/HF; p = 0.035) was significantly higher in the HIIT group compared to the MICT group. Among adolescent boys with obesity, 8-week HIIT and MICT had similar effects on improving VO2peak. HIIT may be superior to MICT to improve endothelial function and vago-sympathetic balance.

[Effects of nitrogen deposition and management intensity on stoichiometry of leaf litter in Moso bamboo forest.] / 氮沉降和经营强度对毛竹林凋落叶生态化学计量特征的影响.

In this study, a field experiment was conducted to estimate the effects of simulated nitrogen (N) deposition (low-N: 30 kg N·hm-2·a-1, moderate-N: 60 kg N·hm-2·a-1, high-N: 90 kg N·hm-2·a-1) on ecological stoichiometry of leaf litter in Moso bamboo forest under conventional management (CM) and intensive management (IM) practices. The results showed that compared with CM, IM significantly increased C, N and P concentrations of leaf litter by 9.3%, 32.4% and 22.7%, respectively, but significantly decreased C:N, C:P and N:P ratios by 17.4%, 54.3% and 44.6%, respectively. In CM Moso bamboo plots, low- and moderate-N deposition significantly increased C, N and P concentrations of leaf litter but decreased C:N, C:P and N:P, high-N deposition significantly increased C, N concentrations, C:P and N:P, but decreased P concentration. In IM Moso bamboo plots, low-N deposition significantly increased P concentration but decreased C concentrations, C:P and N:P, moderate-N deposition significantly increased N and P concentrations but decreased C concentration, C:N, C:P and N:P, high-N deposition significantly increased C:N, C:P and N:P but decreased P concentration. The interaction of management intensity and N deposition significantly influenced stoichiometry of leaf litter, except for C:N. The P concentration of leaf litter was significantly correlated with P concentration in soils.