Department of Physical Medicine and Rehabilitation, University of Colorado School of Medicine, Aurora, CO, USA.
CU Sports Medicine and Performance Center, 2150 Stadium Drive, 2nd Floor, Boulder, CO, 80309, USA.
Sports Med. 2018 Feb;48(2):467-479. doi: 10.1007/s40279-017-0751-x.
Increased muscle mitochondrial mass is characteristic of elite professional endurance athletes (PAs), whereas increased blood lactate levels (lactatemia) at the same absolute submaximal exercise intensities and decreased mitochondrial oxidative capacity are characteristics of individuals with low aerobic power. In contrast to PAs, patients with metabolic syndrome (MtS) are characterized by a decreased capacity to oxidize lipids and by early transition from fat to carbohydrate oxidation (FATox/CHOox), as well as elevated blood lactate concentration [La] as exercise power output (PO) increases, a condition termed 'metabolic inflexibility'.
The aim of this study was to assess metabolic flexibility across populations with different metabolic characteristics.
We used indirect calorimetry and [La] measurements to study the metabolic responses to exercise in PAs, moderately active individuals (MAs), and MtS individuals.
FATox was significantly higher in PAs than MAs and patients with MtS (p < 0.01), while [La] was significantly lower in PAs compared with MAs and patients with MtS. FATox and [La] were inversely correlated in all three groups (PA: r = -0.97, p < 0.01; MA: r = -0.98, p < 0.01; MtS: r = -0.92, p < 0.01). The correlation between FATox and [La] for all data points corresponding to all populations studied was r = -0.76 (p < 0.01).
Blood lactate accumulation is negatively correlated with FATox and positively correlated with CHOox during exercise across populations with widely ranging metabolic capabilities. Because both lactate and fatty acids are mitochondrial substrates, we believe that measurements of [La] and FATox rate during exercise provide an indirect method to assess metabolic flexibility and oxidative capacity across individuals of widely different metabolic capabilities.
增加肌肉线粒体质量是精英职业耐力运动员（PA）的特征，而在相同的绝对亚最大运动强度下增加血乳酸水平（乳酸血症）和降低线粒体氧化能力是低有氧能力个体的特征。与 PA 不同，代谢综合征（MtS）患者的特点是脂质氧化能力降低，以及从脂肪到碳水化合物氧化的早期转变（FATox/CHOox），以及随着运动功率输出（PO）的增加，血乳酸浓度[La]升高，这种情况称为“代谢灵活性降低”。
本研究旨在评估具有不同代谢特征的人群的代谢灵活性。
我们使用间接测热法和[La]测量来研究 PA、中度活跃个体（MA）和 MtS 个体的运动代谢反应。
PA 中的 FATox 明显高于 MA 和 MtS 患者（p<0.01），而[La]在 PA 中明显低于 MA 和 MtS 患者。FATox 和[La]在所有三组中呈负相关（PA：r=-0.97，p<0.01；MA：r=-0.98，p<0.01；MtS：r=-0.92，p<0.01）。所有研究人群的所有数据点的 FATox 和[La]之间的相关性 r=-0.76（p<0.01）。
在代谢能力范围广泛的人群中，运动期间血乳酸积累与 FATox 呈负相关，与 CHOox 呈正相关。因为乳酸和脂肪酸都是线粒体底物，我们认为在运动过程中测量[La]和 FATox 率提供了一种间接方法来评估代谢灵活性和氧化能力在代谢能力差异很大的个体之间的差异。
