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Papers by Sandra Guerra
Fuel and Energy Abstracts , 2011
American Journal of Human Biology , 2002
The aims of this cross-sectional study were 1) to estimate changes in body composition and cardio... more The aims of this cross-sectional study were 1) to estimate changes in body composition and cardiorespiratory fitness across stages of pubertal maturation, and 2) to describe the relationship between maturity status and body fatness, regional fat distribution, and cardiorespiratory fitness. The sample consisted of 494 children (254 males, 240 females), 8–16 years of age. Height and weight were measured with standard anthropometric methods. Percentage of fat (%F) was estimated from two skinfold thicknesses and regional fat distribution was estimated by the ratio of the subscapular to the triceps skinfold (S/T ratio). Biological maturity was based on self-assessment of breast stages in females and pubic hair stages in males. A maximal multistage 20-m shuttle run was used to predict maximal aerobic capacity from maximal aerobic speed. Both VO2max and 20SRT-time were used as indicators of cardiorespiratory fitness. ANCOVA with age as the covariate was used. There were significant differences among girls across pubertal stages. Among boys, only weight and height differed significantly by stage of maturity. When adjusted for maturity status, cardiorespiratory fitness expressed either as VO2/kg body mass or 20SRT-time was inversely associated with %F in both sexes. This suggests that sexual maturity status alone accounts for a small portion of the variance in aerobic fitness. Height, %F and the S/T ratio were also significantly associated with VO2/kg body mass and 20SRT-time. Am. J. Hum. Biol. 14:707–712, 2002. © 2002 Wiley-Liss, Inc.
European Physical Education Review , 2001
This paper analyses literature related to biological risk factors aggregation and the hypothetica... more This paper analyses literature related to biological risk factors aggregation and the hypothetical relationship between physical activity (PA) and aggregation. The regular practice of physical activities has been associated to a healthy lifestyle. When risk factors stemming from cardiovascular diseases (CVD) are present during childhood and adolescence and because the level of habitual PA seem to influence these factors, more intensive PA during this period of life may have an impact in reducing morbidity and mortality of CVD in adult life. Literature does not indicate biological risk factors aggregation for CVD in boys and girls, nevertheless, there is no consensus determining the highest aggregation risk for each one of the sexes. Therefore, results seem to suggest that children or adolescents identified as bearing risk factors should be followed-up to determine whether they possess more aggregated risk factors. Literature is not unanimous in relation to PA and biological risk factors aggregaton for CVD.
Children's Health Care , 2002
ABSTRACT
European Physical Education Review , 2003
Preventive Medicine , 2004
American Journal of Human Biology , 2004
Modifiable cardiovascular risk factors that increase the risk for cardiovascular diseases (CVD) i... more Modifiable cardiovascular risk factors that increase the risk for cardiovascular diseases (CVD) in adult populations have also been observed in pediatric populations. Childhood and adolescence obesity has been strongly implicated in the clustering of risk factors. The aims of the present study were 1) to examine whether clustering of CVD risk factors, either biological risk factors (high blood pressure (HBP), percentage of high fat mass (%HBF), and high total cholesterol (HTC)) and one behavioral/lifestyle risk factor (low physical activity index (LPAI)) exist, and 2) to analyze the relationship between body fatness and the clustering of other risk factors. The cluster of CVD risk factors was determined in 1,533 (8–15 years of age) children, 731 males (age 10.8 ± 2.3 years; weight, 40.6 ± 12.7 kg; height, 143.1 ± 14.1 cm; BMI, 19.4 ± 3.4 kg−2) and 802 females (age, 11.0 ± 2.4; weight, 41.0 ± 12.4; height, 142.8 ± 13.2; BMI, 19.7 ± 3.5). Sex- and age-specific “high risk” quartiles were formed for each of the biological risk factors and the lifestyle factor. Thus, for blood pressure (high blood pressure, HBP), cholesterol (high cholesterol, HTC), and obesity (high percent of body fat, HBF), the sex- and age-adjusted 4th quartile (4Q) was defined as the “high risk” quartile, while for physical activity the 1st quartile (1Q) was defined as the “high risk” quartile. The majority of children (62% of boys and 62% of girls) at risk of obesity are at risk of another risk factor. In our sample, estimated ORs indicated that, compared with 1Q, the “risk of obesity” children and adolescents were two times as likely (P < 0.001) to have two or three risk factors. Our results suggest that children 8–15 years old in the highest quartile of body fatness are an increased risk of having a cluster of other risk factors, namely HBP, HTC, and LPAI. These data provide further evidence that juvenile obesity warrants early intervention because the patterns of unhealthy behavior are formed in adolescence and young adulthood. Am. J. Hum. Biol. 16:556–562, 2004. © 2004 Wiley-Liss, Inc.
American Journal of Human Biology , 2003
The purpose of this study was to examine the weekday patterns of moderate-to-vigorous physical ac... more The purpose of this study was to examine the weekday patterns of moderate-to-vigorous physical activity (MVPA) in school children and adolescents and determine if there are periods of the day that are representative of their typical MVPA. The sample comprised 84 subjects (boys, n = 30; girls, n = 54), age 8–15 years old. Daily totals for the physical activity variables were calculated by summing the values from 13hr of physical activity (PA) measurements (9:00–22:00), with 60-min time blocks comprising each day. The MVPA data values were categorized in four daily periods: morning (9:00–11:59), noon (12:00–14:59), late afternoon (15:00–17.59), and evening (18:00–21.59). Our data show that boys participated significantly more in MVPA than girls. Despite no clear patterns or differences among sex being found, girls showed higher percent of time engaged in MVPA during the morning and early afternoon periods (sum of two periods 51.0%), while boys' percent of time engaged in MVPA is higher at late afternoon and evening periods (sum of two periods 53.8%). The principal components analyses showed four distinct components that accounted for 67% of the variance, as follows: school hours (component 1); lunchtime and outside-school activities (component 2); morning time before school period (component 4); and period before bedtime (component 3) appear as distinct periods of the day. In conclusion, the present study shows that boys engaged more in MVPA than girls. Girls tend to be more active during school periods, while boys are more active after school. Am. J. Hum. Biol. 15:547–553, 2003. © 2003 Wiley-Liss, Inc.
Fuel and Energy Abstracts , 2011
American Journal of Human Biology , 2002
The aims of this cross-sectional study were 1) to estimate changes in body composition and cardio... more The aims of this cross-sectional study were 1) to estimate changes in body composition and cardiorespiratory fitness across stages of pubertal maturation, and 2) to describe the relationship between maturity status and body fatness, regional fat distribution, and cardiorespiratory fitness. The sample consisted of 494 children (254 males, 240 females), 8–16 years of age. Height and weight were measured with standard anthropometric methods. Percentage of fat (%F) was estimated from two skinfold thicknesses and regional fat distribution was estimated by the ratio of the subscapular to the triceps skinfold (S/T ratio). Biological maturity was based on self-assessment of breast stages in females and pubic hair stages in males. A maximal multistage 20-m shuttle run was used to predict maximal aerobic capacity from maximal aerobic speed. Both VO2max and 20SRT-time were used as indicators of cardiorespiratory fitness. ANCOVA with age as the covariate was used. There were significant differences among girls across pubertal stages. Among boys, only weight and height differed significantly by stage of maturity. When adjusted for maturity status, cardiorespiratory fitness expressed either as VO2/kg body mass or 20SRT-time was inversely associated with %F in both sexes. This suggests that sexual maturity status alone accounts for a small portion of the variance in aerobic fitness. Height, %F and the S/T ratio were also significantly associated with VO2/kg body mass and 20SRT-time. Am. J. Hum. Biol. 14:707–712, 2002. © 2002 Wiley-Liss, Inc.
European Physical Education Review , 2001
This paper analyses literature related to biological risk factors aggregation and the hypothetica... more This paper analyses literature related to biological risk factors aggregation and the hypothetical relationship between physical activity (PA) and aggregation. The regular practice of physical activities has been associated to a healthy lifestyle. When risk factors stemming from cardiovascular diseases (CVD) are present during childhood and adolescence and because the level of habitual PA seem to influence these factors, more intensive PA during this period of life may have an impact in reducing morbidity and mortality of CVD in adult life. Literature does not indicate biological risk factors aggregation for CVD in boys and girls, nevertheless, there is no consensus determining the highest aggregation risk for each one of the sexes. Therefore, results seem to suggest that children or adolescents identified as bearing risk factors should be followed-up to determine whether they possess more aggregated risk factors. Literature is not unanimous in relation to PA and biological risk factors aggregaton for CVD.
Children's Health Care , 2002
ABSTRACT
European Physical Education Review , 2003
Preventive Medicine , 2004
American Journal of Human Biology , 2004
Modifiable cardiovascular risk factors that increase the risk for cardiovascular diseases (CVD) i... more Modifiable cardiovascular risk factors that increase the risk for cardiovascular diseases (CVD) in adult populations have also been observed in pediatric populations. Childhood and adolescence obesity has been strongly implicated in the clustering of risk factors. The aims of the present study were 1) to examine whether clustering of CVD risk factors, either biological risk factors (high blood pressure (HBP), percentage of high fat mass (%HBF), and high total cholesterol (HTC)) and one behavioral/lifestyle risk factor (low physical activity index (LPAI)) exist, and 2) to analyze the relationship between body fatness and the clustering of other risk factors. The cluster of CVD risk factors was determined in 1,533 (8–15 years of age) children, 731 males (age 10.8 ± 2.3 years; weight, 40.6 ± 12.7 kg; height, 143.1 ± 14.1 cm; BMI, 19.4 ± 3.4 kg−2) and 802 females (age, 11.0 ± 2.4; weight, 41.0 ± 12.4; height, 142.8 ± 13.2; BMI, 19.7 ± 3.5). Sex- and age-specific “high risk” quartiles were formed for each of the biological risk factors and the lifestyle factor. Thus, for blood pressure (high blood pressure, HBP), cholesterol (high cholesterol, HTC), and obesity (high percent of body fat, HBF), the sex- and age-adjusted 4th quartile (4Q) was defined as the “high risk” quartile, while for physical activity the 1st quartile (1Q) was defined as the “high risk” quartile. The majority of children (62% of boys and 62% of girls) at risk of obesity are at risk of another risk factor. In our sample, estimated ORs indicated that, compared with 1Q, the “risk of obesity” children and adolescents were two times as likely (P < 0.001) to have two or three risk factors. Our results suggest that children 8–15 years old in the highest quartile of body fatness are an increased risk of having a cluster of other risk factors, namely HBP, HTC, and LPAI. These data provide further evidence that juvenile obesity warrants early intervention because the patterns of unhealthy behavior are formed in adolescence and young adulthood. Am. J. Hum. Biol. 16:556–562, 2004. © 2004 Wiley-Liss, Inc.
American Journal of Human Biology , 2003
The purpose of this study was to examine the weekday patterns of moderate-to-vigorous physical ac... more The purpose of this study was to examine the weekday patterns of moderate-to-vigorous physical activity (MVPA) in school children and adolescents and determine if there are periods of the day that are representative of their typical MVPA. The sample comprised 84 subjects (boys, n = 30; girls, n = 54), age 8–15 years old. Daily totals for the physical activity variables were calculated by summing the values from 13hr of physical activity (PA) measurements (9:00–22:00), with 60-min time blocks comprising each day. The MVPA data values were categorized in four daily periods: morning (9:00–11:59), noon (12:00–14:59), late afternoon (15:00–17.59), and evening (18:00–21.59). Our data show that boys participated significantly more in MVPA than girls. Despite no clear patterns or differences among sex being found, girls showed higher percent of time engaged in MVPA during the morning and early afternoon periods (sum of two periods 51.0%), while boys' percent of time engaged in MVPA is higher at late afternoon and evening periods (sum of two periods 53.8%). The principal components analyses showed four distinct components that accounted for 67% of the variance, as follows: school hours (component 1); lunchtime and outside-school activities (component 2); morning time before school period (component 4); and period before bedtime (component 3) appear as distinct periods of the day. In conclusion, the present study shows that boys engaged more in MVPA than girls. Girls tend to be more active during school periods, while boys are more active after school. Am. J. Hum. Biol. 15:547–553, 2003. © 2003 Wiley-Liss, Inc.
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Papers by Sandra Guerra