Cardiovascular factors explain genetic background differences in VO2max

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 ≤ 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 ≤ 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 ≤ 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. Am. J. Hum. Biol. 18:454–460, 2006. © 2006 Wiley‐Liss, Inc.

[1]  G. Hunter,et al.  Physical activity and muscle function but not resting energy expenditure impact on weight gain. , 2005, Journal of strength and conditioning research.

[2]  David R Hillman,et al.  Physiologic responses to incremental and self-paced exercise in COPD: a comparison of three tests. , 2004, Chest.

[3]  G. Hunter,et al.  Aerobic fitness, physiologic difficulty and physical activity in Black and White women , 2004, International Journal of Obesity.

[4]  José R. Fernández,et al.  Using genetic admixture to study the biology of obesity traits and to map genes in admixed populations. , 2004, Nutrition reviews.

[5]  D. Allison,et al.  Association of African genetic admixture with resting metabolic rate and obesity among women. , 2003, Obesity research.

[6]  B. Gower,et al.  Using genetic admixture to explain racial differences in insulin-related phenotypes. , 2003, Diabetes.

[7]  K. Flegal,et al.  Prevalence and trends in obesity among US adults, 1999-2000. , 2002, JAMA.

[8]  G. Hunter,et al.  Free-living activity energy expenditure in women successful and unsuccessful at maintaining a normal body weight. , 2002, The American journal of clinical nutrition.

[9]  G. Hunter,et al.  Relation between in vivo and in vitro measurements of skeletal muscle oxidative metabolism , 2001, Muscle & nerve.

[10]  G. Hunter,et al.  Hemoglobin, muscle oxidative capacity, and VO2max in African-American and Caucasian women. , 2001, Medicine and science in sports and exercise.

[11]  B. Newcomer,et al.  Skeletal muscle metabolism in overweight and post-overweight women: an isometric exercise study using 31P magnetic resonance spectroscopy , 2001, International Journal of Obesity.

[12]  M. Shriver,et al.  Melting curve analysis of SNPs (McSNP): a gel-free and inexpensive approach for SNP genotyping. , 2001, BioTechniques.

[13]  G R Hunter,et al.  Racial differences in energy expenditure and aerobic fitness in premenopausal women. , 2000, The American journal of clinical nutrition.

[14]  G. Hunter,et al.  31P MRS measurement of mitochondrial function in skeletal muscle: reliability, force‐level sensitivity and relation to whole body maximal oxygen uptake , 1995, NMR in biomedicine.

[15]  D R Bassett,et al.  Limiting factors for maximum oxygen uptake and determinants of endurance performance. , 2000, Medicine and science in sports and exercise.

[16]  D. Allison,et al.  Estimating African American admixture proportions by use of population-specific alleles. , 1998, American journal of human genetics.

[17]  W. L. O'Brien,et al.  Effects of exercise training on aerobic fitness in African-American females. , 1998, Ethnicity & disease.

[18]  D A Schoeller,et al.  How much physical activity is needed to minimize weight gain in previously obese women? , 1997, The American journal of clinical nutrition.

[19]  M. Boska,et al.  Adenosine triphosphate production rates, metabolic economy calculations, pH, phosphomonoesters, phosphodiesters, and force output during short‐duration maximal isometric plantar flexion exercises and repeated maximal isometric plantar flexion exercises , 1997, Muscle & nerve.

[20]  D. Arnold,et al.  ADP Recovery After a Brief Ischemic Exercise in Normal and Diseased Human Muscle — a 31P MRS Study , 1996, NMR in biomedicine.

[21]  M. Boska.  ATP production rates as a function of force level in the human gastrocnemius/soleus using 31P MRS , 1994, Magnetic resonance in medicine.

[22]  G. Heath,et al.  Physical Activity Patterns Among Adults in Georgia: Results From the 1990 Behavioral Risk Factor Surveillance System , 1994, Southern medical journal.

[23]  E. Eaker,et al.  Leisure-time physical activity and high-density lipoprotein cholesterol in a biracial community sample. , 1993, Ethnicity & disease.

[24]  D. Lackland,et al.  Leisure time physical activity: are there black/white differences? , 1992, Preventive medicine.

[25]  J. Dempsey,et al.  Effects of incomplete pulmonary gas exchange on VO2 max. , 1989, Journal of applied physiology.

[26]  C. Bouchard,et al.  Skeletal muscle characteristics in sedentary black and Caucasian males. , 1986, Journal of applied physiology.

[27]  W J Schull,et al.  Individual admixture estimates: disease associations and individual risk of diabetes and gallbladder disease among Mexican-Americans in Starr County, Texas. , 1986, American journal of physical anthropology.

[28]  J A Dempsey,et al.  Exercise‐induced arterial hypoxaemia in healthy human subjects at sea level. , 1984, The Journal of physiology.

[29]  R. Veech,et al.  Effects of pH and free Mg2+ on the Keq of the creatine kinase reaction and other phosphate hydrolyses and phosphate transfer reactions. , 1979, The Journal of biological chemistry.

[30]  E. Ravussin,et al.  Substrate utilization using indirect calorimetry during xylitol or sorbitol perfusions. , 1979, The American journal of clinical nutrition.