BACKGROUND: It is unclear how moderate and vigorous intensities of physical activity (PA) are associated with cardiovascular fitness (CVF) and percentage of body fat (%BF) in adolescents. OBJECTIVE: We tested the hypothesis that vigorous PA, to a greater degree than moderate PA, would be associated with better CVF and lower %BF. DESIGN: This was a cross-sectional study of 421 black and white high school students (x age: 16 y). PA was measured with 5 d of accelerometry and expressed in min/d of moderate or vigorous PA. CVF was measured with a multistage treadmill test and was expressed as the oxygen consumption at a heart rate of 170 bpm. %BF was measured with dual-energy X-ray absorptiometry. Multiple regressions were used to determine the degree to which variance in CVF and %BF was explained by PA, after control for age, sex, race, and the sex x race interaction. RESULTS: A higher index for CVF was associated with higher amounts of moderate and vigorous PA; more variance was explained by vigorous than by moderate PA. Lower %BF was associated with higher amounts of vigorous PA but not with the amount of moderate PA. CONCLUSION: Black and white adolescents who engaged in relatively large amounts of free-living vigorous exercise were likely to be relatively fit and lean.
BACKGROUND: It is unclear how moderate and vigorous intensities of physical activity (PA) are associated with cardiovascular fitness (CVF) and percentage of body fat (%BF) in adolescents. OBJECTIVE: We tested the hypothesis that vigorous PA, to a greater degree than moderate PA, would be associated with better CVF and lower %BF. DESIGN: This was a cross-sectional study of 421 black and white high school students (x age: 16 y). PA was measured with 5 d of accelerometry and expressed in min/d of moderate or vigorous PA. CVF was measured with a multistage treadmill test and was expressed as the oxygen consumption at a heart rate of 170 bpm. %BF was measured with dual-energy X-ray absorptiometry. Multiple regressions were used to determine the degree to which variance in CVF and %BF was explained by PA, after control for age, sex, race, and the sex x race interaction. RESULTS: A higher index for CVF was associated with higher amounts of moderate and vigorous PA; more variance was explained by vigorous than by moderate PA. Lower %BF was associated with higher amounts of vigorous PA but not with the amount of moderate PA. CONCLUSION: Black and white adolescents who engaged in relatively large amounts of free-living vigorous exercise were likely to be relatively fit and lean.
Authors: V Carson; R L Rinaldi; B Torrance; K Maximova; G D C Ball; S R Majumdar; R C Plotnikoff; P Veugelers; N G Boulé; P Wozny; L McCargar; S Downs; C Daymont; R Lewanczuk; J McGavock Journal: Int J Obes (Lond) Date: 2013-07-26 Impact factor: 5.095
Authors: Daniel R Taber; Charlotte Pratt; Eileen Y Charneco; Marsha Dowda; Jennie A Phillips; Scott B Going Journal: J Phys Act Health Date: 2013-03-14