CARDIOVASCULAR FITNESS (CVF) IN BLACK AND WHITE TEENS

Abstract

PURPOSE To determine whether: (1) CVF, PA and SED differed among black and white boys and girls, and (2) CVF differed between those who did or did not report vigorous PA (VPA). METHODS CVF was measured via a graded treadmill test. Moderate and VPA were measured using 4 to 7 24-h recalls. SED was the sum of 7 activities from the recalls. RESULTS CVF differed between the race-sex subgroups (p < 0001). White boys (WB) (lsmean±SE: 30.3±0.7 ml/kg/min) and black boys (BB) (29.6±0.8 ml/kg/min) were higher than white girls (WG) (23.1±0.7 ml/kg/min) who were higher than black girls (BG) (20.3±0.6 ml/kg/min). Boys (0.92±0.06 h/d) reported more VPA (p < 0.0001) than girls (0.36±0.05 h/d). BG (4.3±0.1 h/d) reported more SED than WG (3.6±0.2 h/d, p < 0.05). A regression model that included race, sex, age, and their 2-way interactions was used to evaluate PA and SED as predictors of CVF. When PA was entered first into the model, it explained 4% of the variance (p < 0.0001); adding SED explained less than 1% more (p = 0.055). When SED was entered first into the model, it explained 2.5% of the variance (p < 0.001); adding PA explained an additional 2.5% (p < 0.001). A greater proportion of whites reported VPA (77%) compared to blacks (65%, p < 0.05), while a greater proportion of boys (87%) reported VPA compared to girls (60%, p < 0.0001). Boys who reported VPA had higher CVF (31.0±0.6 ml/kg/min) than: (1) boys who reported no VPA (23.3±1.4 ml/kg/min, p < 0.0001), (2) girls who reported VPA (23.0±0.5 ml/kg/min, p < 0.0001), and (3) girls who did not report any VPA (19.7±0.7 ml/kg/min, p < 0.0001). Girls who reported VPA had greater CVF than girls who did not (p < 0.005). CONCLUSIONS (1) Boys were more fit than girls, and reported greater amounts of VPA and less SED, (2) individuals who reported VPA had greater levels of CVF, and (3) PA was an independent predictor of CVF, while SED explained only a small additional proportion of the variance. Supported by NIH (HL64157).