Abstract
BackgroundSex comparisons between girls and boys in response to exercise in trained adolescents are missing and we investigated similarities and differences as a basis for clinical interpretation and guidance.MethodsA total of 24 adolescent females and 27 adolescent males aged 13–19 years underwent a maximal bicycle exercise stress test with measurement of cardiovascular variables, cardiac output, lung volumes, metabolic factors/lactate concentrations and breath-by-breath monitoring of ventilation, and determination of peak VO2.ResultsMaximum heart rate was similar in females (191 ± 9 bpm) and males (194 ± 7 bpm), cardiac index at maximum exercise was lower in females (7.0 ± 1.0 l/min/m2) than in males (8.3 ± 1.4 l/min/m2, P < 0.05). Metabolic responses and RQ at maximum exercise were similar (females: 1.04 ± 0.06 vs. males: 1.05 ± 0.05). Peak VO2 was lower in females (2.37 ± 0.34 l/min) than in males (3.38 ± 0.49 l/min, P < 0.05). When peak VO2 was normalized to leg muscle mass sex differences disappeared (females: 161 ± 21 ml/min/kg vs. males: 170 ± 23 ml/min/kg). The increase in cardiac index during exercise is the key factor responsible for the greater peak VO2 in adolescent boys compared to girls.ConclusionsDifferences in peak VO2 in adolescent boys and girls disappear when peak VO2 is normalized to estimated leg muscle mass and therefore provide a tool to conduct individual and intersex comparisons of fitness when evaluating adolescent athletes in aerobic sports.
Highlights
Sex comparisons between girls and boys in response to exercise in trained adolescents are missing and we investigated similarities and differences as a basis for clinical interpretation and guidance
Age was similar in males and females, the males being taller and heavier but with similar body mass index compared to female athletes (Table 1)
We demonstrate that maximum heart rate, systemic lactate levels, and RQ are similar in adolescent boys and girls, which indicates that maximum performance is associated with the same metabolic adaptation irrespective of sex
Summary
Sex comparisons between girls and boys in response to exercise in trained adolescents are missing and we investigated similarities and differences as a basis for clinical interpretation and guidance. Physical activity and training is important for initiating and sustaining cardiovascular health. Encouragement from childhood and the possibility to participate in sports activity is a major health issue which must be sustained. Reaching adolescence increasing expectations and competitive demands have gradually emerged as an important aspect of recreational sports in the young. Adolescence is the age interval at which the young sport competitor starts building local and national team careers, prompting coaches and physical trainers to interpret test results and understand and take into account possible sex-specific characteristics. Maximal oxygen uptake has been extensively investigated in children [4,5,6,7] and adults [8], but clinical context sex comparisons in the adolescent age-group 13 to 19 years of age in trained subjects are missing
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