Limits...
Sex differences in response to maximal exercise stress test in trained adolescents.

Fomin Å, Ahlstrand M, Schill HG, Lund LH, Ståhlberg M, Manouras A, Gabrielsen A - BMC Pediatr (2012)

Bottom Line: Peak VO(2) was lower in females (2.37 ± 0.34 l/min) than in males (3.38 ± 0.49 l/min, P < 0.05).When peak VO(2) 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 VO(2) in adolescent boys compared to girls.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Cardiology, Karolinska Institutet, Karolinska University Hospital, N1:05, SE-17176, Stockholm, Sweden.

ABSTRACT

Background: 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.

Methods: A 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 VO(2).

Results: Maximum 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/m(2)) than in males (8.3 ± 1.4 l/min/m(2), P < 0.05). Metabolic responses and RQ at maximum exercise were similar (females: 1.04 ± 0.06 vs. males: 1.05 ± 0.05). Peak VO(2) was lower in females (2.37 ± 0.34 l/min) than in males (3.38 ± 0.49 l/min, P < 0.05). When peak VO(2) 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 VO(2) in adolescent boys compared to girls.

Conclusions: Differences in peak VO(2) in adolescent boys and girls disappear when peak VO(2) 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.

Show MeSH

Related in: MedlinePlus

Heart rate, blood pressure, and cardiac index during baseline and at maximum exercise in boys and girls. Recordings of heart rate, blood pressure, and cardiac index during baseline and at maximum exercise in female (♀, N = 24; cardiac index measurements N = 23) and male (♂, N = 27; cardiac index measurements N = 26) subjects. During exercise only systolic blood pressure was recorded. *) denotes statistical significant difference (p < 0.05 by unpaired t-test with correction for multiple comparisons) between female and male subjects with regard to resting heart rate, resting and maximum systolic blood pressure, and maximum cardiac index.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3472286&req=5

Figure 1: Heart rate, blood pressure, and cardiac index during baseline and at maximum exercise in boys and girls. Recordings of heart rate, blood pressure, and cardiac index during baseline and at maximum exercise in female (♀, N = 24; cardiac index measurements N = 23) and male (♂, N = 27; cardiac index measurements N = 26) subjects. During exercise only systolic blood pressure was recorded. *) denotes statistical significant difference (p < 0.05 by unpaired t-test with correction for multiple comparisons) between female and male subjects with regard to resting heart rate, resting and maximum systolic blood pressure, and maximum cardiac index.

Mentions: Female subjects exhibited a lower systolic blood pressure (124 ± 11 mmHg; mean ± SD) and higher resting heart rate (77 ± 8 bpm) compared to male participants (137 ± 13 mmHg and 71 ± 11 bpm, respectively; P < 0.05), whereas diastolic blood pressure (females: 74 ± 8 mmHg vs. males: 72 ± 11 mmHg) and resting cardiac index (females: 3.8 ± 0.8 l/min/m2 vs. males: 4.1 ± 1.0 l/min/m2) did not differ between sexes (Figure 1). Ventilated lung volumes at rest were lower in females than in males (P < 0.05, Table 2). There were no differences in metabolic variables; blood lactate concentration, blood pH, blood base excess, and blood HCO3- at rest (Table 2). At 60 watt (initial step) exercise absolute VCO2 were slightly lower in females (0.55 ± 0.13 l/min) than in males (0.65 ± 0.11 l/min, p < 0.05), whereas VO2 did not differ (females: 0.79 ± 0.12 l/min vs. males: 0.85 ± 0.15 l/min) leading to a minor difference in RQ (females: 0.71 ± 0.12 vs. males: 0.77 ± 0.08, P < 0.05). Ventilation volumes at this initial step of exercise were similar comparing females and males (Table 2).


Sex differences in response to maximal exercise stress test in trained adolescents.

Fomin Å, Ahlstrand M, Schill HG, Lund LH, Ståhlberg M, Manouras A, Gabrielsen A - BMC Pediatr (2012)

Heart rate, blood pressure, and cardiac index during baseline and at maximum exercise in boys and girls. Recordings of heart rate, blood pressure, and cardiac index during baseline and at maximum exercise in female (♀, N = 24; cardiac index measurements N = 23) and male (♂, N = 27; cardiac index measurements N = 26) subjects. During exercise only systolic blood pressure was recorded. *) denotes statistical significant difference (p < 0.05 by unpaired t-test with correction for multiple comparisons) between female and male subjects with regard to resting heart rate, resting and maximum systolic blood pressure, and maximum cardiac index.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3472286&req=5

Figure 1: Heart rate, blood pressure, and cardiac index during baseline and at maximum exercise in boys and girls. Recordings of heart rate, blood pressure, and cardiac index during baseline and at maximum exercise in female (♀, N = 24; cardiac index measurements N = 23) and male (♂, N = 27; cardiac index measurements N = 26) subjects. During exercise only systolic blood pressure was recorded. *) denotes statistical significant difference (p < 0.05 by unpaired t-test with correction for multiple comparisons) between female and male subjects with regard to resting heart rate, resting and maximum systolic blood pressure, and maximum cardiac index.
Mentions: Female subjects exhibited a lower systolic blood pressure (124 ± 11 mmHg; mean ± SD) and higher resting heart rate (77 ± 8 bpm) compared to male participants (137 ± 13 mmHg and 71 ± 11 bpm, respectively; P < 0.05), whereas diastolic blood pressure (females: 74 ± 8 mmHg vs. males: 72 ± 11 mmHg) and resting cardiac index (females: 3.8 ± 0.8 l/min/m2 vs. males: 4.1 ± 1.0 l/min/m2) did not differ between sexes (Figure 1). Ventilated lung volumes at rest were lower in females than in males (P < 0.05, Table 2). There were no differences in metabolic variables; blood lactate concentration, blood pH, blood base excess, and blood HCO3- at rest (Table 2). At 60 watt (initial step) exercise absolute VCO2 were slightly lower in females (0.55 ± 0.13 l/min) than in males (0.65 ± 0.11 l/min, p < 0.05), whereas VO2 did not differ (females: 0.79 ± 0.12 l/min vs. males: 0.85 ± 0.15 l/min) leading to a minor difference in RQ (females: 0.71 ± 0.12 vs. males: 0.77 ± 0.08, P < 0.05). Ventilation volumes at this initial step of exercise were similar comparing females and males (Table 2).

Bottom Line: Peak VO(2) was lower in females (2.37 ± 0.34 l/min) than in males (3.38 ± 0.49 l/min, P < 0.05).When peak VO(2) 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 VO(2) in adolescent boys compared to girls.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Cardiology, Karolinska Institutet, Karolinska University Hospital, N1:05, SE-17176, Stockholm, Sweden.

ABSTRACT

Background: 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.

Methods: A 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 VO(2).

Results: Maximum 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/m(2)) than in males (8.3 ± 1.4 l/min/m(2), P < 0.05). Metabolic responses and RQ at maximum exercise were similar (females: 1.04 ± 0.06 vs. males: 1.05 ± 0.05). Peak VO(2) was lower in females (2.37 ± 0.34 l/min) than in males (3.38 ± 0.49 l/min, P < 0.05). When peak VO(2) 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 VO(2) in adolescent boys compared to girls.

Conclusions: Differences in peak VO(2) in adolescent boys and girls disappear when peak VO(2) 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.

Show MeSH
Related in: MedlinePlus