title: Ethnicity affects aerobic fitness in US adolescent girls.
abstract: The purpose of this investigation was to determine whether aerobic fitness (VO2max) differed between black (N = 40) and white (N = 53) adolescent girls who were similar in age (13.5 yr) and percent body fat (24.6%). Expired gases were collected continuously while each girl performed a standard Bruce protocol to volitional exhaustion on a motorized treadmill (TM). Heart rates (HR) were measured during the exercise testing via telemetry. Fat-free mass (FFM) was estimated with total body electrical conductivity (TOBEC). Average (+/- SD) maximum HR (black = 194 +/- 7; white = 198 +/- 8) and respiratory exchange ratios (black = 1.17 +/- 0.08; white = 1.22 +/- 0.09) did not differ between subject groups. Aerobic fitness was significantly lower (P < 0.01) lower in black versus white girls when VO2max was expressed relative to body weight (31.8 +/- 5.8 vs 38.5 +/- 6.8 ml.kg(-1).min(-1)) and body weight raised to the 0.67 power (120.9 +/- 19.5 vs 138.5 +/- 20.7 ml.kg(-0.67).min-1). Treadmill time to exhaustion was significantly less (P < 0.01) in the black (8.49 +/- 1.30 min) versus white (9.41 +/- 1.60) subjects. Also, black subjects demonstrated less ability to utilize O2 during maximal exercise at a given FFM. This suggests the black girls' FFM contained a smaller percentage of skeletal muscle mass that could be utilized during treadmill exercise. It is possible that lower aerobic fitness values seen in the black girls are related to a combination of anatomical, physiological and/or behavioral factors.
authors.affiliation: Department of Pediatrics, Baylor College of Medicine, Texas Children's Hospital, Houston, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Pivarnik
authors.forename: M S
authors.initials: MS
authors.lastname: Bray
authors.forename: A C
authors.initials: AC
authors.lastname: Hergenroeder
authors.forename: R B
authors.initials: RB
authors.lastname: Hill
authors.forename: W W
authors.initials: WW
authors.lastname: Wong
mesh_terms: D000273:Adipose Tissue; D000293:Adolescent; D000332:Aerobiosis; D001741:Black or African American; D044383:Black People; D001823:Body Composition; D015992:Body Mass Index; D001835:Body Weight; D004553:Electric Conductivity; D005006:Ethnicity; D005080:Exercise Test; D017079:Exercise Tolerance; D005260:Female; D006339:Heart Rate; D006801:Humans; D018482:Muscle, Skeletal / Q000033:anatomy & histology; D010101:Oxygen Consumption; D010809:Physical Fitness; D011659:Pulmonary Gas Exchange; D013997:Time Factors; D044465:White People