Influence of cardiac functional capacity on gender differences in maximal oxygen uptake in children.
OBJECTIVE
To examine the role of gender differences in cardiac functional capacity in explaining higher mean values for maximal oxygen uptake (VO(2)max) in boys than in girls.


METHODS
Comparative group exercise testing.


METHODS
Pediatric exercise testing laboratory.


METHODS
Twenty-five prepubertal boys (mean [+/- SD] age, 12 +/- 0.4 years) and 24 premenarcheal girls (mean age, 11.7 +/- 0.5 years).


METHODS
Maximal incremental upright cycle exercise.


RESULTS
Mean values for VO(2)max were the following: boys, 47.2 +/- 6.1 mL/kg/min; and girls, 40.4 +/- 5.8 mL/kg/min (16.8% difference; p < 0.05). The average maximal stroke index with Doppler echocardiography was 62 +/- 9 mL/m(2) for boys and 55 +/- 9 mL/m(2) for girls (12.7% difference; p < 0.05). No significant gender differences were seen in maximal heart rate or arterial venous oxygen difference. When VO(2)max and maximal stroke volume (SV) were expressed relative to lean body mass, gender differences declined but persisted, falling to 6.2% and 5.2%, respectively.


CONCLUSIONS
These findings indicate that differences in SV as well as in body composition contribute to gender-related variations in VO(2)max during childhood. Whether this reflects small gender differences in relative heart size or dynamic factors influencing ventricular preload and contractility during exercise is unknown.
Rowland
T
T
Department of Pediatrics (Dr. Rowland, and Mss. Martel and Ferrone), Baystate Medical Center, Springfield, MA 01199, USA.
Goff
D
D
Martel
L
L
Ferrone
L
L
D001823:Body Composition / Q000502:physiology; D002648:Child; D004734:Energy Metabolism / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D009200:Myocardial Contraction / Q000502:physiology; D010100:Oxygen / Q000502:physiology*; D012727:Sex Characteristics; D013318:Stroke Volume / Q000502:physiology*
D010100:Oxygen