Department of Physical Therapy, Federal University of Sao Carlos, Sao Carlos, Sao Paulo, Brazil.
Laboratory of Pulmonary and Exercise Immunology (LABPEI), Brazilian Institute of Teaching and Research in Pulmonary and Exercise Immunology (IBEPIPE), Nove de Julho University, Sao Paulo, Sao Paulo, Brazil.
Auton Neurosci. 2018 Sep;213:43-50. doi: 10.1016/j.autneu.2018.05.008. Epub 2018 May 18.
Obesity is often associated with increased risk of cardiometabolic morbidities and mortality. However, evidence shows that some obese individuals are more likely to develop such risk factors early in life, including those with Metabolic Syndrome (MetS). Whether the presence of MetS in obese people impairs cardiac autonomic modulation (CAM) remains to be investigated.
Cross-sectional study. Sixty-six subjects were classified as normal-weight (NW, n = 24) or obese (BMI ≥ 30 kg·m): metabolically healthy (MHO, n = 19) vs unhealthy (MUHO, n = 23: NCEP/ATPIII-MetS criteria). Body composition (bioimpedance), metabolic (glucose-insulin/lipid) and inflammatory profiles were determined. Linear and nonlinear heart rate variability (HRV) indices were computed at rest and during the submaximal six-minute step test (6MST). Blood pressure (BP) and metabolic and ventilatory variables were assessed (oxygen uptake, VO; carbon dioxide production, VCO; minute ventilation, V) during the 6MST and the maximal cardiopulmonary exercise testing (CPX).
All groups reached the same 6MST intensity (VO ~ 80% and HR ~ 87% of CPX peak values). Both obese groups, independently of MetS, presented higher BP and lower maximal VO than NW. However, HRV differed between groups according to MetS at rest and during exercise: MUHO had lower meanRRi and SD1 than NW and lower RMSSD and pNN50 than MHO at rest; during exercise, the lowest SDNN, TINN, SD1 and Shannon entropy were observed for MUHO. Significant correlations were found between MetS, insulin resistance and HRV indices; and between insulin resistance and aerobic capacity (VO).
Obesity per se impairs aerobic-hemodynamic responses to exercise. However, MetS in obese young adults negatively impacts overall HRV, parasympathetic activity and HRV complexity.
肥胖常与心血管代谢疾病风险和死亡率增加相关。然而，有证据表明，一些肥胖个体更有可能在生命早期出现这些风险因素，包括患有代谢综合征（MetS）的个体。肥胖人群中 MetS 的存在是否会损害心脏自主神经调节（CAM）仍有待研究。
横断面研究。66 名受试者被分为正常体重（NW，n=24）或肥胖（BMI≥30kg·m）组：代谢健康（MHO，n=19）与代谢不健康（MUHO，n=23：NCEP/ATPIII-MetS 标准）。测定身体成分（生物阻抗）、代谢（血糖-胰岛素/脂质）和炎症谱。在休息和最大六分钟台阶测试（6MST）期间计算线性和非线性心率变异性（HRV）指数。在 6MST 和最大心肺运动测试（CPX）期间评估血压（BP）和代谢及通气变量（摄氧量，VO；二氧化碳产生，VCO；分钟通气量，V）。
所有组均达到相同的 6MST 强度（VOCPX 峰值的 80%，HRCPX 峰值的 87%）。两个肥胖组，不论 MetS 如何，均表现出较高的 BP 和较低的最大 VO 比 NW。然而，HRV 在静息和运动时根据 MetS 而在各组之间不同：MUHO 的平均 RRi 和 SD1 均低于 NW，RMSSD 和 pNN50 均低于 MHO；在运动时，MUHO 的 SDNN、TINN、SD1 和 Shannon 熵最低。发现 MetS、胰岛素抵抗与 HRV 指数之间存在显著相关性；胰岛素抵抗与有氧能力（VO）之间也存在相关性。
肥胖本身会损害运动时的有氧-血液动力学反应。然而，肥胖年轻成人中 MetS 会对整体 HRV、副交感神经活动和 HRV 复杂性产生负面影响。
