Maurice Savage

Cardiorespiratory fitness, physical activity, and arterial stiffness: the Northern Ireland Young Hearts Project.

Poor cardiorespiratory fitness and low physical activity have been identified as determinants of greater arterial stiffness, a mechanism that can partially explain the association of both variables with increased cardiovascular disease. However, the nature of these associations are not clear because cardiorespiratory fitness and physical activity can both mediate and confound the associations of one another with arterial stiffness. This issue was therefore examined in a population-based cohort of young adults. Subjects included 405 young men and women participating in an ongoing longitudinal study, the Northern Ireland Young Hearts Project. Pulse wave velocity was used to determine arterial stiffness in 2 arterial segments (aortoiliac and aortodorsalis pedis) using a noninvasive optical method. Cardiovascular fitness was estimated with a submaximal cycle test of physical work capacity and physical activity was estimated using a modified Baecke questionnaire. Associations were investigated with the use of multiple linear regression models with adjustment for potential confounders and/or intermediate variables. Cardiorespiratory fitness and sports-related physical activity (but not leisure- and work-related physical activity) were inversely associated with arterial stiffness in young adults. The associations between sports-related physical activity and arterial stiffness were strongly mediated by cardiorespiratory fitness, whereas physical activity levels did not disturb the associations between cardiopulmonary fitness and arterial stiffness. These findings suggest that arterial stiffness-related benefits of exercise are most likely to accrue if exercise prescription in young adults targets improvements in cardiorespiratory fitness.

Physical activity, sports participation and risk factors in adolescents

The purpose of this study was to analyze the relationships between physical activity (ACT), including sports participation (SP) and antecedent risk factors for coronary heart disease (CHD), in a representative sample of adolescents from Northern Ireland, a region of high coronary mortality. Biological and behavioral risk factors were measured in a random sample of 1015 school children aged 12 and 15 yr. ACT and SP were assessed by self-report questionnaire, and relationships with biological risk factors were analyzed with stepwise multiple linear regression after controlling for potential confounders. Results showed that in 15-yr-old males ACT was beneficially associated with systolic blood pressure (P < 0.05), lipid profile, and cardiorespiratory fitness (both P < 0.01). In 15-yr-old females, SP was associated beneficially with fatness and cardiorespiratory fitness. Odds ratios calculated from logistic regression revealed that for the older children, a relatively small drop (-20%) in ACT (boys) or SP (girls) was significantly related to the probability of exposure to multiple risk factors. Overall, relationships were stronger for males rather than females and for older rather than younger children. This study provides further evidence for beneficial associations between ACT, SP, and CHD risk status in adolescents.

Fitness, fatness, and coronary heart disease risk in adolescents: the Northern Ireland Young Hearts Project

PURPOSE The purpose of this study was to examine the independence and relative strengths of association between coronary heart disease (CHD) risk status and both body fatness and cardiorespiratory (C-R) fitness in 12- and 15-yr-old adolescents. METHODS The study cohort consisted of 1015 schoolchildren aged 12 and 15 yr (251 12-yr-old boys, 258 12-yr-old girls, 252 15-yr-old boys, and 254 15-yr-old girls), representing a 2% random sample of each population group. For each child, height, weight, sexual maturity (pubertal status), skin-fold thicknesses (4 sites), blood pressure (random zero sphygmomanometer), nonfasting serum total, and high density lipoprotein (HDL)-cholesterol and C-R fitness (20-m shuttle run; 20-MST) were determined under standardized conditions. Socioeconomic status and habitual physical activity were also determined from questionnaire information. Multiple regression analyses were carried out to examine relationships between five CHD risk factors, and fitness and fatness and to examine the relative strengths of fitness and fatness on CHD risk status, correcting for potential confounding variables. RESULTS Our main findings were: 1) Relationships between fatness and CHD risk factors are invariably stronger than between fitness and the same risk factors. For example, partially adjusted standardized regression coefficients for 12-yr-old boys revealed significant relationships between all five CHD risk factors and fatness, compared with three of five for fitness. The corresponding figures for 12-yr-old girls were three of five (fatness) and one of five (fitness). Broadly similar results were apparent for 15-yr-olds. 2) Although relationships between fitness and CHD risk factors do not survive further adjustment for fatness, the relationships between fatness and CHD risk are more robust and are unaffected by further adjustment for fitness. CONCLUSION Our results indicate that the observed relationships between C-R fitness and CHD risk status in adolescents are mediated by fatness, whereas the observed relationships with fatness are independent of fitness. Primary prevention of CHD during childhood should therefore concentrate upon preventing or reversing undue weight gain.

Trends in blood pressure over 10 years in adolescents: analyses of cross sectional surveys in the Northern Ireland Young Hearts project

Abstract Objective To examine secular trends in blood pressure over a 10 year period between two representative cohorts of adolescents from Northern Ireland. Design Repeat cross sectional study. Setting Randomly selected post-primary schools from Northern Ireland. Participants 1015 adolescents studied between 1989 and 1990, and 2017 adolescents studied between 1999 and 2001. Participants were aged 12 or 15 years. Main outcome measures Systolic and diastolic blood pressure measured by one observer in each study. Results The four groups for sex and age showed decreases in both systolic blood pressure (mean decrease 7.7 mm Hg to 10.0 mm Hg) and diastolic blood pressure (8.8 mm Hg to 11.0 mm Hg). These decreases were not accounted for by adjustment for potential confounders including age, height, body mass index, smoking, physical activity, aerobic fitness, and stratification of school by education board area and type. The findings were not altered by additional adjustment for social class, pubertal status, birth weight, and infant feeding. No evidence was found of systematic variation between observers. Conclusions Substantial decreases in systolic and diastolic blood pressure over the past decade in adolescents from Northern Ireland are likely to have important benefits to public health and may help offset the increasing risk of cardiovascular disease due to increases in obesity.

Effect of a COL1A1 Sp1 binding site polymorphism on arterial pulse wave velocity: an index of compliance.

Reduced arterial compliance precedes changes in blood pressure, which may be mediated through alterations in vessel wall matrix composition. We investigated the effect of the collagen type I-&agr;1 gene (COL1A1) +2046G>T polymorphism on arterial compliance in healthy individuals. We recruited 489 subjects (251 men and 238 women; mean age, 22.6±1.6 years). COL1A1 genotypes were determined using polymerase chain reaction and digestion by restriction enzyme Bal 1. Arterial pulse wave velocities were measured in 3 segments, aortoiliac (PWVA), aortoradial (PWVB), and aorto-dorsalis-pedis (PWVF), as an index of compliance using a noninvasive optical method. Data were available for 455 subjects. The sample was in Hardy-Weinberg equilibrium with genotype distributions and allele frequencies that were not significantly different from those reported previously. The T allele frequency was 0.22 (95% confidence interval, 0.19 to 0.24). Two hundred eighty-three (62.2%) subjects were genotype GG, 148 (35.5%) subjects were genotype GT, and 24 (5.3%) subjects were genotype TT. A comparison of GG homozygotes with GT and TT individuals demonstrated a statistically significant association with arterial compliance: PWVF 4.92±0.03 versus 5.06±0.05 m/s (ANOVA, P =0.009), PWVB 4.20±0.03 versus 4.32±0.04 m/s (ANOVA, P =0.036), and PWVA 3.07±0.03 versus 3.15±0.03 m/s (ANOVA, P =0.045). The effects of genotype were independent of age, gender, smoking, mean arterial pressure, body mass index, family history of hypertension, and activity scores. We report an association between the COL1A1 gene polymorphism and arterial compliance. Alterations in arterial collagen type 1A deposition may play a role in the regulation of arterial compliance.

What determines drop out in prospective studies of coronary heart disease risk factors between youth and young adulthood: the Young Hearts Study

The growing recognition of the importance of early life factors in the development of coronary heart disease (CHD) may increase prospective research in this period of life. From a methodological point of view, drop out of subjects, particularly when this is selective, is a major threat to the validity of the results. Specific information about determinants of drop out in current studies may therefore yield important information for future studies. We have analysed risk of drop out in the Young Hearts Project, a prospective study in Northern Ireland.1 The Young Hearts Project is a prospective cohort study, which started in two cohorts of 12 year old boys (n=251) and girls (n=258) and 15 year old boys (n=252) and girls (n=254) in Northern Ireland (overall response rate 78%) in 1988. Its aim and design have been described elsewhere in detail.1 In 1992/93 these children were re-examined …

Sex specific difference in the relation between birth weight and arterial compliance in young adults: The Young Hearts Project

Low birth weight and small size at birth have been related to raised blood pressure in both childhood and adult life1and a previous report has demonstrated lower arterial compliance in middle aged adults who were small at birth.2 It has been hypothesised that, in the growth retarded fetus, reduced arterial compliance results from impaired elastin synthesis in the walls of large arteries.3 Elastin synthesis in blood vessels seems to be primarily limited to the fetal and perinatal periods3 with no appreciable synthesis during adulthood. Investigation of the relation between birth weight and arterial compliance in young people, as in this study, presents an opportunity to test this hypothesis and has the advantage that the relation should not obscured by existing atherosclerosis, which is related to both birth weight and arterial compliance. Subjects were recruited from 1015 randomly selected children who participated in a survey of cardiovascular risk factors performed in Northern Ireland in 1989 (the Young Hearts cohort). All subjects were invited to attend further screening between 1997 and 1999, when aged 21 to 25 years (the Young Hearts 3 survey). Altogether 489 (48.2%) of the original subjects attended (251 men, 238 women). …