高强度间歇训练减少腹部内脏脂肪的效果、机制及心脏风险性研究

Abdominal obesity is a negative health risk factor that will lead to various metabolic disease and increase the risk of developing cardiovascular disease. Traditionally, the exercise for fat reduction has focused on low-moderate intensity exercise mode. However, this method is time-consuming and less sustainable. High-intensity interval training (HIIT) is time-efficient, nevertheless, if it is effective and safe in achieving abdominal visceral fat reduction needs to be further confirmed. . Our previous studies suggest that HIIT is likely to be more effective in reducing abdominal visceral fat than moderate-intensity continuous training (MICT). We speculate the mechanisms are that high-intensity exercise secretes more lipolytic hormones, increases HSL phosphorylation, and consequently, improves fat mobilization in comparison with moderate-intensity exercise. In addition, more protein expression of PGC-1—FNDC5—Irisin—UCP1 are activated, resulting in the increase of fat oxidation. Also, previous studies including ours imply that the cardiac risk of HIIT is possibly not higher than that of MICT.. This project which includes human and animal studies aims to further confirm that, in case that the minimum exercise volume is met, HIIT is better than MICT in reducing abdominal visceral fat by increasing fat mobilization and oxidation. In addition, it aims to testify that the HIIT on cardiac risk injury is not higher than MICT, providing the evidence for implementing HIIT safely.

腹部内脏脂肪过多是导致现代文明病的重要因素。传统中低强度运动减肥方式时间太长，不易坚持。高强度间歇训练（HIIT）运动时间短，但能否减少腹部内脏脂肪尚不明确。即使有效，其安全性也需得到保证。我们前期研究提示HIIT比中等强度持续训练更有利于减少腹部内脏脂肪，且不会加大心脏的运动风险性。推测其减脂机制是通过更强烈的机体刺激，释放更多的脂解类激素而提高脂肪动员，并显著激活PGC-1α—FNDC5—Irisin—UCP1通路而加速脂肪氧化。本研究拟采用人体和动物实验相结合，证实在满足最低运动量的基础上，运动时间较短的HIIT也可以通过更强烈的机体刺激，提高腹部内脏脂肪动员、加速脂肪氧化，从而比传统长时间耐力训练减少更多的腹部内脏脂肪；另，拟证实高强度运动的心脏风险性不会比传统耐力训练更高，为实践中应用HIIT提供心脏安全性的证据。

传统中强度持续训练（MICT）减肥处方运动时间太长，不易坚持。时间较短的高强度间歇训练（HIIT）是否也可以减肥值得研究。本课题（1）系统研究了三类代表性HIIT减少青年肥胖女性腹部内脏脂肪的效果；（2）初步揭示了HIIT减少腹部内脏脂肪的内在生物学机制；（3）探索了HIIT对青年肥胖女性的心脏风险性。得出以下重要结论：.1. 与相同做功量MICT相比，三种代表性HIIT均具有相似的减少青年肥胖女性全身脂肪量的效果，而HIIT减少腹部内脏脂肪量的效果更明显。.2. 一次急性HIIT和MICT均可促进肥胖人群生长激素和肾上腺素分泌，但HIIT刺激肾上腺素分泌的效果比MICT更明显。.3. HIIT可特异性激活腹部内脏脂肪组织激素敏感性脂肪酶磷酸化。.4. 相比MICT，HIIT更显著地促进内脏白色脂肪组织棕色化，与交感神经对脂肪细胞的调控活动密切相关。.5. 与MICT相比，长期HIIT可更好改善高脂膳食导致的内脏脂肪细胞儿茶酚胺抵抗，使脂肪在受到刺激时更容易被动员。.6. 长期HIIT过程中，急性运动后血清心肌肌钙蛋白T（cTnT）升高发生在训练早期阶段，随着训练次数增加运动后cTnT升高逐渐消失。.7. 在不同月经周期阶段（卵泡期和黄体期），一次急性HIIT或MICT后血清cTnT均显著升高，且升高峰值相似。. 这些发现确认了HIIT的减肥作用，尤其是对内脏脂肪的特殊作用，从理论上突破了“运动减肥只能采用中低强度长时间耐力训练”的限制；初步揭示了HIIT减少腹部内脏脂肪的内在生物学机制与运动后的脂解效应增强有关，也与长期锻炼使脂肪细胞在应激状态下的甘油三酯分解增强和棕色化有关，扩展了对运动减肥内在机制的理解；从心肌损伤及心脏应激的角度，证实了HIIT训练的心脏风险不高于MICT，为实践中安全推广应用HIIT提供了一定的理论依据。