Objectively measured physical activity in the 1993 Pelotas (Brazil) birth cohort

The Joint Associations of Physical Activity and Sedentary Behaviors on Adiposity during Adolescence: The 1993 Pelotas (Brazil) Cohort Study

A prior study conducted in high-income countries demonstrated that specific sedentary behavior, such as TV viewing, is prospectively associated with adiposity in both active and inactive adolescents. The aim of this study was to examine the joint associations of sedentary behaviors and moderate- and vigorous-intensity physical activity (MVPA) with adiposity among Brazilian adolescents. This prospective cohort study included 377 participants of the 1993 Pelotas (Brazil) Study who completed an accelerometry assessment at age 13 years and a dual-energy X-ray absorptiometry (DXA) assessment at age 18 years. Accelerometer-measured MVPA was dichotomized into high (≥60 min/day) and low (<60 min/day). Accelerometer-measured sedentary time (SED) was dichotomized into low (<49 min/h) and high (≥49 min/h) based on the median. Self-reported TV viewing time was also dichotomized into low (<3 h/day) and high (≥3 h/day) based on the median. We combined the two MVPA groups (high and low) and two SED groups (low and high) to form the four MVPA&SED groups: high&low, high&high, low&low, and low&high. We also created four MVPA&TV groups in the same manner. Fat mass index (FMI; kg/m2) was calculated using DXA-derived fat mass. Multivariable linear regression analyses compared FMI at 18 years among the four MVPA&SED groups and among the four MVPA&TV groups, adjusting for socioeconomic status, energy intake, and baseline adiposity. The analysis results showed that SED or TV viewing time was not prospectively associated with adiposity in both active and inactive Brazilian adolescents. This study suggests that the association between specific sedentary behaviors, such as TV viewing, and adiposity may differ across societal settings-in this case, high-income vs. middle-income countries.

Impact of Recreational Sports Activities on Metabolic Syndrome Components in Adolescents

We investigated the impact of a sports activities program on metabolic syndrome (MetS) components and pre-MetS among adolescents. Blood samples, blood pressure, weight, height, body mass index, waist circumference, body fat percentage, frequency of food consumption, daily time in moderate-to-vigorous physical activity (MVPA), and sedentary behavior (SB) of 92 male adolescents aged 14-18 years (16.07 ± 0.93) were evaluated. From this initial sample, 36 participants (39.1%) were diagnosed with pre-MetS or MetS and were invited to participate in the intervention program. Twelve individuals diagnosed with pre-MetS or MetS agreed to participate in a recreational sports activities program lasting 14 weeks. The pre- and post-sport program comparison showed a reduction in total cholesterol, low-density lipoprotein, and non-high-density lipoprotein (HDL), and an increase in HDL and MVPA time in the intervention group. Sports activities accounted for 42% of the MVPA daily recommendation, and at the end of the intervention period, only seven subjects maintained a positive diagnosis for pre-MetS or MetS. This study showed that recreational sports activities had a significant impact on the lipid profile.

Níveis insuficientes de atividade física de adolescentes associados a fatores sociodemográficos, ambientais e escolares

Resumo Este estudo investigou as associações entre o nível de atividade física com os fatores sociodemográficos, ambientais e escolares de adolescentes. Participaram 2.545 jovens de 14 a 18 anos dos municípios da Grande Florianópolis. Foi utilizada a versão curta do Questionário Internacional de Atividade Física (IPAQ). A prevalência de jovens inativos foi de 48,6%, sendo maior no sexo feminino (53,9%). Para as moças, a inatividade física esteve associada com a falta de lugares apropriados e gratuitos para a prática de atividade física (OR = 1,30 IC95%1,05-1,82), independente da influência das outras variáveis. Já para os rapazes, aqueles que não possuíam atividade profissional (OR = 1,54 IC95%1,14-2,08), mães de menor instrução (OR = 0,41 IC95% 0,27-0,75) ou mães com ensino superior (OR = 0,35 IC95% 0,17- 0,73), pertencentes a cidades de grande porte (OR = 1,64 IC95%1,17-2,31) e classificação socioeconômica baixa quando comparada à média (OR = 0,69 IC95% 0,49-0,97), apresentaram maior chance de inatividade física. Observou-se que as variáveis sociodemográficas estiveram associadas ao comportamento inativo dos rapazes e às variáveis ambientais se associaram a inatividade física das moças. Já dentre os fatores escolares, apenas a reprovação escolar foi associada com inatividade, e somente para as moças.

Physical Activity Throughout Adolescence and Hba1c in Early Adulthood: Birth Cohort Study

BACKGROUND

Physical inactivity is responsible for 7% of diabetes deaths worldwide, but little is known whether low levels of physical activity (PA) during adolescence increase the risk of diabetes in early adulthood. We evaluated the cross-sectional and longitudinal associations between PA throughout adolescence and HbA1c concentration in early adulthood.

METHODS

HbA1c was measured by high performance liquid chromatography. PA was assessed by self-report at the ages of 11, 15, and 18 years and by accelerometry at the ages of 13 (subsample) and 18 years. The loss percentages of follow up were 12.5% at 11 years, 14.4% at 15 years, and 18.7% at 18 years.

RESULTS

At 18 years, boys showed higher HbA1c than girls. At age 18 years, accelerometrybased PA at 18 years was inversely related to HbA1c levels in boys. Self-reported leisure-time PA at ages 11, 15, and 18 were unrelated to HbA1c in both genders. PA at 13 years of age was unrelated to HbA1c among both genders. In trajectory analysis, PA and accelerometer PA trajectories were not associated with later HbA1c.

CONCLUSIONS

Objectively measured PA at 18 years was cross-sectionally inversely associated with HbA1c in boys only. No prospective associations were identified.

Physical activity levels in three Brazilian birth cohorts as assessed with raw triaxial wrist accelerometry

BACKGROUND

Data on objectively measured physical activity are lacking in low- and middle-income countries. The aim of this study was to describe objectively measured overall physical activity and time spent in moderate-to-vigorous physical activity (MVPA) in individuals from the Pelotas (Brazil) birth cohorts, according to weight status, socioeconomic status (SES) and sex.

METHODS

All children born in 1982, 1993 and 2004 in hospitals in the city of Pelotas, Brazil, constitute the sampling frame; of these 99% agreed to participate. The most recent follow-ups were conducted between 2010 and 2013. In total, 8974 individuals provided valid data derived from raw triaxial wrist accelerometry. The average acceleration is presented in milli-g (1 mg = 0.001g), and time (min/d) spent in MVPA (>100 mg) is presented in 5- and 10-min bouts.

RESULTS

Mean acceleration in the 1982 (mean age 30.2 years), 1993 (mean age 18.4 years) and 2004 (mean age 6.7 years) cohorts was 35 mg, 39 mg and 60 mg, respectively. Time spent in MVPA was 26 [95% confidence interval (CI) 25; 27], 43 (95% CI 42; 44) and 45 (95% CI 43; 46) min/d in the three cohorts, respectively, using 10-min bouts. Mean MVPA was on average 42% higher when using 5-min bouts. Males were more active than females and physical activity was inversely associated with age of the cohort and SES. Normal-weight individuals were more active than underweight, overweight and obese participants.

CONCLUSIONS

Overall physical activity and time spent in MVPA differed by cohort (age), sex, weight status and SES. Higher levels of activity in low SES groups may be explained by incidental physical activity.