Roy Jane L P, Hunter Gary R, Fernandez Jose R, McCarthy John P, Larson-Meyer D Enette, Blaudeau Tamilane E, Newcomer Bradley R
Department of Human Studies, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA.
Am J Hum Biol. 2006 Jul-Aug;18(4):454-60. doi: 10.1002/ajhb.20509.
The purpose of this study was to further explore factors that may be related to ethnic differences in the maximum rate at which an individual can consume oxygen (VO2max) between 20 African American (AA) and 30 European American (EA) sedentary women who were matched for body weight (kg) and fat-free mass (FFM). VO2max (l/min) was determined during a graded treadmill exercise test. Submaximal steady-state heart rate and submaximal VO2 were determined at a treadmill speed of 1.3 m/sec and a 2.5% grade. Hemoglobin (Hb) was determined by the cyanide method, muscle oxidative capacity by 31P magnetic resonance spectroscopy (ADP time constant), and FFM (kg) by dual-energy x-ray absorptiometry. Genetic classification was self-reported, and in a subset of the sample (N = 32), the determinants of ethnicity were measured by African genetic admixture. AA women had significantly reduced VO2max, Hb levels, and muscle oxidative capacity (longer ADP time constants, P < or = 0.05) than EA women. Submaximal oxygen pulse (O2Psubmax), ADP time constant, Hb, and ethnic background were all significantly related to VO2max (ml/kg/min and ml/kg FFM/min, all P < or = 0.01). By multiple regression modeling, Hb, O2Psubmax, muscle oxidative capacity, and ethnicity were found to explain 61% and 57% of the variance of VO2max in ml/kg/min and ml/kg FFM/min, respectively. Muscle oxidative capacity and O2Psubmax were both significantly and independently related to VO2max in all three models (P < or = 0.05), whereas Hb and ethnicity were not. These results suggest that mitochondrial muscle oxidative capacity and oxygen delivery capabilities, as determined by O2Psubmax, account for most if not all of the ethnic differences in VO2max.
本研究的目的是进一步探究可能与20名非洲裔美国（AA）久坐不动女性和30名欧洲裔美国（EA）久坐不动女性之间最大摄氧量（VO2max）的种族差异相关的因素，这些女性在体重（kg）和去脂体重（FFM）方面进行了匹配。在分级跑步机运动测试期间测定VO2max（升/分钟）。在跑步机速度为1.3米/秒和坡度为2.5%时测定次最大稳态心率和次最大VO2。采用氰化物法测定血红蛋白（Hb），采用31P磁共振波谱法（ADP时间常数）测定肌肉氧化能力，采用双能X线吸收法测定FFM（kg）。种族分类由自我报告得出，在样本的一个子集中（N = 32），通过非洲遗传混合来测量种族的决定因素。与EA女性相比，AA女性的VO2max、Hb水平和肌肉氧化能力显著降低（ADP时间常数更长，P≤0.05）。次最大氧脉搏（O2Psubmax）、ADP时间常数、Hb和种族背景均与VO2max（毫升/千克/分钟和毫升/千克FFM/分钟，所有P≤0.01）显著相关。通过多元回归建模发现，Hb、O2Psubmax、肌肉氧化能力和种族分别解释了VO2max在毫升/千克/分钟和毫升/千克FFM/分钟变异的61%和57%。在所有三个模型中，肌肉氧化能力和O2Psubmax均与VO2max显著且独立相关（P≤0.05），而Hb和种族则不然。这些结果表明，由O2Psubmax所决定的线粒体肌肉氧化能力和氧输送能力，即便不是全部，也占了VO2max中大部分种族差异的原因。
