Modeling the dynamics of BMI changes during adolescence. The Oporto Growth, Health and Performance Study.

OBJECTIVES: The aims of this study were twofold: (i) to model changes in body mass index (BMI) of 10-18-year-old adolescents, and (ii) to investigate the effects of total physical activity (TPA), physical fitness (PF), sleep duration and fruit/vegetable consumption in BMI trajectories across time. METHODS: Data were obtained from the Oporto Growth, Health and Performance Study and comprised 6894 adolescents (3418 girls) divided into four age cohorts (10, 12, 14 and 16 years) measured annually for 3 years. BMI was computed using the standard formula (kg m(-2)); TPA was estimated with the Baecke questionnaire; PF measures included 1-mile run/walk, 50 yard dash (50YD), standing long jump (SLJ), handgrip strength (HGr) and agility shuttle run. Longitudinal changes in BMI were analyzed using the multilevel modeling approach. RESULTS: The average BMI at age of peak of height velocity was 20.7±0.07 kg m(-2) for girls (P<0.001) and 20.58±0.06 kg m(-2) for boys (P<0.001). The annual increment in BMI was 1.36±0.04 kg m(-2), P<0.001 and 1.23±0.03 kg m(-2), P<0.001 for girls and boys, respectively. PF were related to BMI trajectories in both sexes (Girls: ß1mile=0.12±0.02, P<0.001; ßSLJ=-0.01±0.00, P<0.001; ß50YD=0.28±0.05, P<0.001; ßHGr=-8.91±0.54, P<0.001; Boys: ß1mile=0.18±0.02, P<0.001; ßSLJ=-0.01±0.00, P<0.001; ß50YD=0.26±0.04, P<0.001; and ßHGr=-8.15±0.45, P<0.001). TPA only showed significant, but positive, association with girls' BMI trajectories (ß=0.10±0.03, P=0.001). After adjusting for the covariates, sleep duration and fruit/vegetable intake did not show any significant association with BMI trajectories either sex. CONCLUSIONS: BMI increased linearly with age in both gender. PF levels are negatively associated with BMI across time in both boys and girls. Therefore, promotion of PF in the adolescent years seems to be effective in the early prevention of obesity.

Effects of walking and strength training on resting and exercise cardiovascular responses in patients with intermittent claudication.

BACKGROUND: Exercise training is recommended as the first-line therapy for intermittent claudication patients. However, the effects of exercise therapy on cardiovascular function of these patients have been poorly studied. The aim of this study is to compare the effects of walking and strength training on cardiovascular responses assessed at rest and during exercise in patients with intermittent claudication. PATIENTS AND METHODS: Thirty-four patients with stable symptoms of intermittent claudication were randomized into two groups: strength training (ST) consisting of eight exercises, three sets of 10 repetitions, intensity of 11 - 13 on 15-grade Borg scale, 2-min interval between sets; and walking training (WT) consisting of walking on a treadmill, 15 bouts of 2-min, intensity of 11 - 13 on 15-grade Borg scale, with a 2-min interval between bouts. Before and after 12 weeks, blood pressure, heart rate and rate pressure product were measured at rest and during a progressive treadmill test until maximal claudication pain. RESULTS: Fifteen patients in each group completed the training program. After the training programs, resting systolic blood pressure (ST:-6 ± 13 mmHg and WT:-3 ± 18 mmHg, P = .04), heart rate (ST: -6 ± 10 bpm and WT:-2 ± 9 bpm, P = .03), and rate pressure product (ST:-1485 ± 1442 mmHg*bpm and WT:- 605 ± 2145 mmHg*bpm, P = .01) decreased significantly and similarly in both groups. Submaximal systolic blood pressure (ST: -14 ± 23 mmHg and WT:-6 ± 23 mmHg, P = .02), and rate pressure product (ST:-1579 ± 3444 mmHg*bpm and WT: -1264 ± 3005 mmHg*bpm, P = .04) decreased significantly and similarly in both groups. There were no changes in submaximal heart rate after ST and WT. Maximal systolic blood pressure, heart rate, and rate pressure product did not change in either group, although maximal exercise time increased similarly in the ST and WT groups (+31 ± 19 %, and +31 ± 32 %, respectively, P < .01). CONCLUSIONS: Strength and walking trainings promoted similar increases in walking capacity and decreases in resting and submaximal exercise cardiovascular load.

Finger blood pressure during leg resistance exercise.

Blood pressure (BP) assessment during resistance exercise can be useful to avoid high BP, reducing cardiovascular risk, especially in hypertensive individuals. However, non-invasive accurate technique for this purpose is not available. The aim of this study was to compare finger photoplethysmographic (FPP) and intra-arterial BP values and responses during resistance exercise. Eight non-medicated hypertensive subjects (5 males, 30-60 years) were evaluated during pre-exercise resting period and during three sets of the knee extension exercise performed at 80% of 1RM until fatigue. BP was measured simultaneously by FPP and intra-arterial methods. Data are mean+/-SD. Systolic BP was significantly higher with FPP than with intra-arterial: at pre-exercise (157+/-13 vs. 152+/-10 mmHg; p<0.01) and the mean (202+/-29 vs. 198+/-26 mmHg; p<0.01), and the maximal (240+/-26 vs. 234+/-16 mmHg; p<0.05) values achieved during exercise. The increase in systolic BP during resistance exercise was similar between FPP and intra-arterial (+73+/-29 vs. +71+/-18 mmHg; p=0.59). Diastolic BP values and increases were lower with FPP. In conclusion, FPP provides similar values of BP increment during resistance exercise than intra-arterial method. However, it overestimates by 2.6+/-6.1% the maximal systolic BP achieved during this mode of exercise and underestimates by 8.8+/-5.8% the maximal diastolic BP.