The Body Fat-Cognition Relationship in Healthy Older Individuals: Does Gynoid vs Android Distribution Matter?

OBJECTIVE: To examine the relationship between regional and whole body fat accumulation and core cognitive executive functions. DESIGN: Cross-sectional study. SETTINGS AND PARTICIPANTS: 78 healthy men and women aged between 65 and 75 years recruited through consumer's database. MEASUREMENTS: DXA measured percentage total body fat, android, gynoid distribution and android/gynoid ratio; inhibition and working memory updating through Random Number Generation test and cognitive flexibility by Trail Making test. First-order partial correlations between regional body fat and cognitive executive function were computed partialling out the effects of whole body fat. Moderation analysis was performed to verify the effect of gender on the body fat-cognition relationship. RESULTS: Results showed a differentiated pattern of fat-cognition relationship depending on fat localization and type of cognitive function. Statistically significant relationships were observed between working memory updating and: android fat (r = -0.232; p = 0.042), gynoid fat (r = 0.333; p = 0.003) and android/gynoid ratio (r = -0.272; p = 0.017). Separating genders, the only significant relationship was observed in females between working memory updating and gynoid fat (r = 0.280; p = 0.045). In spite of gender differences in both working memory updating and gynoid body fat levels, moderation analysis did not show an effect of gender on the relationship between gynoid fat and working memory updating. CONCLUSIONS: Results suggest a protective effect of gynoid body fat and a deleterious effect of android body fat. Although excessive body fat increases the risk of developing CDV, metabolic and cognitive problems, maintaining a certain proportion of gynoid fat may help prevent cognitive decline, particularly in older women. Guidelines for optimal body composition maintenance for the elderly should not target indiscriminate weight loss, but weight maintenance through body fat/lean mass control based on non-pharmacological tools such as physical exercise, known to have protective effects against CVD risk factors and age-related cognitive deterioration.

Vitamin D, Muscle Function, and Cardiorespiratory Fitness in Adolescents From the Young Hearts Study.

CONTEXT: Vitamin D insufficiency is common among the adolescent population and may have implications for health outcomes in later life. Few studies have investigated the role of vitamin D status in muscle function and cardiorespiratory fitness (CRF) during adolescence. OBJECTIVE: The aim of this study was to investigate the association between vitamin D status and fat-free mass (FFM), muscle strength, muscle power, and CRF in a representative sample of adolescents from Northern Ireland. DESIGN, SETTING, AND PARTICIPANTS: This was a cross-sectional study involving 1015 adolescents (age 12 and 15 y), who had 25-hydroxyvitamin D [25(OH)D] data available as part of the Young Hearts Study 2000. MAIN OUTCOME MEASURES: The main outcome measures of this study were FFM (kg) and FFM corrected for height [fat-free mass index; FFM (kg)/height (m(2))], muscle strength (kg), peak muscle power (kW) and VO2 max (CRF; mL/kg/min). RESULTS: Multinomial regression analyses, controlling for environmental and lifestyle factors, demonstrated that boys age 15 years in the highest tertile of standardized serum 25(OH)D concentration (> 51 nmol/L) had significantly higher muscle strength (ß = 3.90; P ≤ .001) compared with those in the lowest tertile (< 32 nmol/L). These results were not evident in any other age-sex group and vitamin D status was not significantly associated with muscle power or CRF in any of the four age-sex groups. CONCLUSION: These results support a role for vitamin D in muscle function in adolescent males and suggest the need for more research in this vulnerable age group.

Fruit and vegetable consumption and muscle strength and power during adolescence: a cross-sectional analysis of the Northern Ireland Young Hearts Project 1999-2001.

OBJECTIVES: To examine the association between fruit and vegetable (FV) consumption and muscle strength and power in an adolescent population. METHODS: We conducted a cross-sectional analysis among 1019 boys and 998 girls, aged 12 and 15 years, who participated in The Young Hearts Project. FV consumption (excluding potatoes) was assessed by 7-d diet history. Grip strength and jump power was assessed with a dynamometer and Jump-MD meter, respectively. Associations between FV consumption and strength and power were assessed by regression modelling. RESULTS: Boys and girls with the highest FV intakes (>237.71 g/d and >267.57 g/d, respectively, based on the highest tertile) had significantly higher jump power than those with the lowest intakes (<135.09 g/d and <147.43 g/d, respectively), after adjustment for confounding factors. Although girls with the highest FV intakes had higher grip strength than those with the lowest intakes, no significant independent associations were evident between FV intake and grip strength in boys or girls. Similar findings were observed when FV were analysed separately. CONCLUSIONS: Higher FV consumption in this group of adolescents was positively associated with muscle power. There was no independent association between higher FV consumption and muscle strength. Intervention studies are required to determine whether muscle strength and power can be improved through increased FV consumption.

Dietary glycemic index and glycemic load in relation to changes in body composition measures during adolescence: Northern Ireland Young Hearts Study.

BACKGROUND: Epidemiologic evidence on the influence of dietary glycemic index (GI) and glycemic load (GL) on the development of obesity is limited. OBJECTIVE: This prospective study examined the associations between dietary GI and GL and changes in body composition measures during adolescence. DESIGN: In a representative sample of Northern Irish adolescents aged 12 years at baseline and 15 years at follow-up (n=426), dietary intake was assessed by a diet history interview. Body composition measures included body mass index (BMI; kg m(-2)), BMI z-score, sum of four skinfold thicknesses, percentage body fat, fat mass index (FMI; kg m(-2)) and fat-free mass index (kg m(-2)). RESULTS: After adjustment for potential confounding factors, baseline GI was associated with increased change in FMI. Mean (95% confidence interval) values of changes in FMI according to tertiles of baseline GI were 0.41 (0.25, 0.57), 0.42 (0.26, 0.58) and 0.67 (0.51, 0.83) kg m(-2), respectively (P for trend=0.03). There was no significant association of baseline GI with changes in other body composition measures (P for trend≥0.054). Conversely, baseline GL showed no association with changes in any of the measures (P for trend≥0.41). Furthermore, changes in GI or GL were not associated with changes in any of the measures (P for trend≥0.16). CONCLUSION: Dietary GI at age 12 years was independently associated with increased change in FMI between ages 12 and 15 years in a representative sample from Northern Ireland, whereas dietary GL showed no association with changes in any of the body composition measures examined.

Adiponectin multimers, body weight and markers of cardiovascular risk in adolescence: Northern Ireland Young Hearts Project.

BACKGROUND: Research examining the relationship between adiponectin (AN) isoforms, body weight and cardiovascular (CV) risk factors is limited, particularly in younger populations. OBJECTIVES: To investigate the inter-relationships between AN isoforms and CV risk factors, and their dependence on body weight status, in adolescents. DESIGN: Blood samples from 92 obese, 92 overweight and 92 normal weight age- and sex-matched adolescents were analysed for traditional cardiovascular disease (CVD) risk biomarkers and also total, high molecular weight (HMW), medium and low molecular weight (LMW) AN. RESULTS: A significant inverse association was observed between total and HMW AN and waist-hip ratio (P=0.015, P=0.006, respectively), triglycerides (P=0.003, P=0.003, respectively) and systolic blood pressure (P=0.012, P=0.024, respectively) and a significant positive association with high-density lipoprotein (P<0.001, P<0.001, respectively) in multi-adjusted analyses. There was no evidence of a relationship between multimeric AN and high-sensitivity C-reactive protein. There was also little evidence of a relationship between LMW AN and CVD risk factors. There was a strong, body mass index (BMI)-independent, association between AN, CVD biomarkers and the hypertriglyceridemic waist phenotype. CONCLUSION: Prominent, BMI-independent associations between total and HMW AN, but not LMW AN, and CVD risk factors were already evident in this young population. This research in adolescents supports the contention that AN subfractions may have different biological actions. These associations in apparently healthy adolescents suggest an important role for AN and its subfractions in the pathogenesis of metabolic syndrome traits and indicate that the potential for total or HMW AN to act as early universal biomarkers of CV risk warrants further study.

Vitamin D status and parathyroid hormone relationship in adolescents and its association with bone health parameters: analysis of the Northern Ireland Young Heart's Project.

UNLABELLED: In girls, a plateau in parathyroid hormone (PTH) was observed at a 25-hydroxyvitamin D (25(OH)D) concentration of approximately 60 nmol/l. In boys, there was no plateau in PTH concentrations as 25(OH)D concentration increased. A 25(OH)D threshold of 60 nmol/l appears to have implications for bone health outcomes in both girls and boys. INTRODUCTION: Our objective was to investigate if there is a threshold 25(OH)D concentration where a plateau in PTH concentration is evident and to examine the impact of this relationship on bone mineral density (BMD) and bone turnover in a representative sample of adolescents. METHODS: We conducted a cross-sectional analysis among 1,015 Northern Irish adolescents aged 12 and 15 years. Serum 25(OH)D, PTH, osteocalcin, type 1 collagen cross-linked C-telopeptide (CTx), and BMD of the nondominant forearm and heel were measured. Nonlinear regression analysis was used to model the association between 25(OH)D and PTH. RESULTS: In girls, a plateau in PTH was observed at a 25(OH)D concentration of approximately 60 nmol/l (PTH = 47.146 + 370.314 x exp((-0.092 x 25(OH)D))) while no plateau in PTH was observed in boys (PTH = 42.144 + 56.366 x exp((-0.022 x 25(OH)D))). Subjects with 25(OH)D levels <60 nmol/l had significantly higher osteocalcin concentrations (P < 0.05) compared with those who had >or=60 nmol/l, while no significant (P > 0.05) differences were noted for CTx concentrations. In girls only, nondominant forearm BMD but not heel BMD was significantly higher (P = 0.046) in those with 25(OH)D concentrations >or= 60 nmol/l. CONCLUSIONS: Serum 25(OH)D levels above 60 nmol/l in Northern Irish adolescent girls prevent an increase in serum PTH levels and maintaining 25(OH)D >60 nmol/l in both girls and boys may lead to improved bone health outcomes.

Tracking of energy and nutrient intakes from adolescence to young adulthood: the experiences of the Young Hearts Project, Northern Ireland.

OBJECTIVE: To assess tracking of energy and nutrient intakes between adolescence and young adulthood. DESIGN: Longitudinal study of a random sample of adolescents (aged 15 years at baseline). The extent of tracking of dietary intakes (assessed by diet history) was investigated using weighted kappa statistics (kappa). SETTING: Northern Ireland population survey. SUBJECTS: Adolescents who participated in the Young Hearts Project, Northern Ireland at age 15 years, and subsequently at young adulthood aged between 20 and 25 years (n=245 males, n=231 females). RESULTS: Despite overall increases in height and weight (both P<0.001), increases in body mass index in males (P<0.001) and body fatness in females (P<0.001), median reported intakes of energy (kJ kg(-1) day(-1)), carbohydrate (g day(-1)) and fat (g day(-1)) decreased (all P<0.001) over time. Expressed as nutrient densities (per MJ), diets at young adulthood were overall richer in thiamin, vitamin B6, total folate (all P<0.001), vitamin C (P<0.01) and vitamin D (P<0.05). Whereas the nutrient density of the males' diets decreased over time for calcium (P<0.05) and vitamin A (P<0.001), iron and riboflavin densities increased in the females' diet (P<0.001). Tracking of energy (MJ day(-1)) and nutrient intakes (expressed per MJ day(-1)) at the individual level was only poor to fair (all kappa<0.25), indicating substantial drift of subjects between the low, medium and high classes of intake with increasing age. CONCLUSIONS: These data suggest that individual dietary patterns exhibited at 15 years of age are unlikely to be predictive of dietary intakes at young adulthood.

Training effects of short bouts of stair climbing on cardiorespiratory fitness, blood lipids, and homocysteine in sedentary young women.

OBJECTIVES: To study the training effects of eight weeks of stair climbing on Vo2max, blood lipids, and homocysteine in sedentary, but otherwise healthy young women. METHODS: Fifteen women (mean (SD) age 18.8 (0.7) years) were randomly assigned to control (n = 7) or stair climbing (n = 8) groups. Stair climbing was progressively increased from one ascent a day in week 1 to five ascents a day in weeks 7 and 8. Training took place five days a week on a public access staircase (199 steps), at a stepping rate of 90 steps a minute. Each ascent took about two minutes to complete. Subjects agreed not to change their diet or lifestyle over the experimental period. RESULTS: Relative to controls, the stair climbing group displayed a 17.1% increase in Vo2max and a 7.7% reduction in low density lipoprotein cholesterol (p < 0.05) over the training period. No change occurred in total cholesterol, high density lipoprotein cholesterol, triglycerides, or homocysteine. CONCLUSIONS: The study confirms that accumulating short bouts of stair climbing activity throughout the day can favourably alter important cardiovascular risk factors in previously sedentary young women. Such exercise may be easily incorporated into the working day and therefore should be promoted by public health guidelines.

Ten-year trends for fatness in Northern Irish adolescents: the Young Hearts Projects--repeat cross-sectional study.

OBJECTIVE: To examine secular trends in measures of fatness over a 10-y period (the 1990s) in Northern Irish schoolchildren. DESIGN: Repeat cross-sectional surveys. SUBJECTS: In total, 12- and 15-y-old children randomly selected from post-primary schools. A total of 1015 children studied between 1989 and 1990, and 2017 studied between 1999 and 2001. MEASUREMENTS: The same study methods were applied in both surveys. Body mass index (BMI) was calculated from height and weight, and percentage body fat (%BF) was derived from skinfold measurements at four sites. Dietary intake was assessed using a diet history method and habitual physical activity (PA) was estimated from a self-report questionnaire. RESULTS: Increases were seen in both height and weight in all age-sex groups. The overall prevalence of overweight/obesity increased from 15.0 to 19.6%, but 12-y-old girls contributed most to this increase (15.9-26.3%), with a modest increase observed also in 15-y-old boys. Increases in mean BMI (19.2-20.3 kg/m2) and mean %BF (25.8-27.1%) were seen in 12-y-old girls, with no significant changes in any of the other subgroups. Mean energy intake increased in girls but not in boys, while mean PA score decreased in 12-y-old girls, but was unchanged in the other three groups. All age-sex groups showed substantial increases in the sugar intake while fat intake increased in girls and decreased in boys. CONCLUSION: Increases in indices of fatness were seen among school-age children in Northern Ireland during the 1990s. Trends differed between age-sex groups with the largest changes seen in 12-y-old girls. It remains to be seen whether the large increase in overweight/obesity in this group tracks into adulthood, with consequences for chronic disease incidence in women.

Total homocysteine is not a determinant of arterial pulse wave velocity in young healthy adults.

AIMS: Hyperhomocysteinaemia has been associated with reduced pulse wave velocity (PWV) in patients with end-stage renal disease and in those with hypertension. The aim of this study was to examine the association between total homocysteine (tHcy) concentrations, the biochemical and genetic determinants of tHcy and PWV in healthy young adults. METHODS AND RESULTS: A total of 489 subjects aged 20-25 years participated. A fasting blood sample was taken and PWV measured using a non-invasive optical method. tHcy did not correlate with PWV, whether assessed at the aorto-iliac segment (P = 0.18), the aorto-radial segment (P = 0.39) or the aorto-dorsalis-pedis segment (P = 0.22). When tHcy was classified into normal (<15) and high (> or =15micromol/l), PWV did not differ between the two groups at any segment. PWV did not differ by MTHFR C677T or NOS3 G894T genotype, even when smoking and folate sub-groups were considered. Considering aortic PWV as a dependent variable, stepwise regression analysis showed that the only parameter entering the model for all segments was systolic blood pressure (aorto-iliac, P < 0.001; aorto-radial, P = 0.01; aorto-dorsalis-pedis, P = 0.001). Age, sex, COL1A1 genotype and triglycerides entered the model significantly for two of three segments. CONCLUSION: This study shows that arterial PWV is not associated with tHcy in a healthy young population.

A longitudinal study through adolescence to adulthood: the Young Hearts Project, Northern Ireland.

The Young Hearts (YH) Project is an ongoing study of biological and behavioural risk factors for cardiovascular disease in a representative sample of young people from Northern Ireland, a region of high coronary mortality. This article describes the cross-sectional clinical, dietary and lifestyle data obtained from individuals (aged 20-25 y) who participated in phase 3 of the project (YH3). A total of 489 individuals (251 males, 238 females) participated in YH3 (48.2% response rate). Some 31.1% of participants at YH3 were overweight (BMI >25 kg/m(2)) with 4.4% of males and 8.0% of females were obese (BMI >30 kg/m(2)). More females than males had a very poor fitness (55.0 vs 22.1%, chi-squared 51.70, d.f. 1, P<0.001) and did not participate in any sporting or exercise activity (38.4 vs 24.9%, chi-squared 10.26, d.f. 1, P=0.001). Over 20% of participants had a raised total serum cholesterol (>5.2 mmol/l). More females had a raised serum LDL-cholesterol (>3.0 mmol/l) than males (44.6 vs 34.6%, chi-squared 4.39, d.f. 1, P<0.05). Over 46% of participants reported energy intakes from fat above recommended levels, and 68.5% of participants had saturated fat intakes above those recommended (Dietary reference values for food energy and nutrients for the United Kingdom. HMSO: London, 1991). Just over half of the study population reported alcohol intakes in excess of recommended sensible limits set by the Royal College of Physicians (A great and growing evil: the medical consequences of alcohol abuse. Tavistock: London, 1987), with 36.7% of males and 13.4% of females reporting intakes over twice these recommended limits. A total of 37% of the study population smoked. During young adulthood, individuals may be less amenable to attend a health-related study and recruitment of participants to the current phase of the study proved a major problem. However, these data constitute a unique developmental record from adolescence to young adulthood in a cohort from Northern Ireland and provide additional information on the impact of early life, childhood and young adulthood on the development of risk for chronic disease.

Relationship between physical activity and bone mineral status in young adults: the Northern Ireland Young Hearts Project.

Physical activity during the first three decades of life may increase peak bone mass and reduce future osteoporosis risk. The aim of this study was to determine the extent to which different components of physical activity may influence bone mineral status within a representative population sample of young men and women. Bone mineral density (BMD) and content (BMC) were determined at the lumbar spine and femoral neck in 242 men and 212 women, aged 20-25 years, by dual-energy X-ray absorptiometry. Physical activity was assessed by a self-report questionnaire designed to measure the frequency and duration of physical activity and its components (i.e., work, non-sports leisure, sports-related activities, and peak strain sports activities). Potential confounding factors such as height, weight, diet, and smoking habits were also assessed. In multivariate linear regression models, sports activity and peak strain sports activity undertaken by men were strongly associated with both lumbar spine BMD (beta = 0.35 [0.21, 0.49] and beta = 0.31 [0.17, 0.44], respectively) and BMC (beta = 0.33 [0.21, 0.45] and beta = 0.26 [0.14, 0.38], respectively) and femoral neck BMD (beta = 0.35 [0.21, 0.48] and beta = 0.27 [0.14, 0.40], respectively) and BMC (beta = 0.32 [0.19, 0.44] and beta = 0.29 [0.17, 0.41], respectively) (all p < 0.01), but work and non-sports leisure activities were not. In women, there were no associations between bone measurements and any component of physical activity. In models involving all subjects the gender/sports activity, but not the gender/peak strain, interaction term was statistically significant. Sports activity explained 10.4% of the observed variance in lumbar spine BMD in men, but <1% in women. These results demonstrate the importance of sports activities, especially those involving high peak strain, in determining peak bone status in young men. Failure to observe this association in women reflects their lower participation in such activities, but they may have the same capacity to benefit from these activities as men. Intervention studies are warranted to determine whether peak bone density in women can be improved by participating, during childhood and adolescence, in sports activities involving high peak strain.

The effect of nutrient intake on bone mineral status in young adults: the Northern Ireland young hearts project.

Optimizing peak bone mass in early life may reduce osteoporosis risk in later life. Such optimization may be partly dependent upon diet. In the present study, nutrient intakes and selected lifestyle parameters were assessed in adolescent subjects (238 males, 205 females; aged 15 y) and again, in the same subjects, on one occasion in young adulthood (aged between 20 and 25 y). The extent of the relationships between these parameters and bone mineral density (BMD), dual energy X-ray absorptiometry (DXA), lumbar spine (L2-L4), and femoral neck measured concurrently with diet in young adulthood only, was assessed. Adjusted linear regression models were constructed. Variables included a measure of pubertal status (at age 15 y), age (at young adulthood), height, weight, physical activity, smoking, and mean daily intakes of energy, calcium, protein, vitamin D, phosphorus, total fat, and alcohol. In both sexes, body weight at adolescence and young adulthood was the only factor consistently positively associated with BMD at both measurement sites. Effects of nutrient intake on BMD were inconsistent. Vitamin D and calcium intakes reported by female adolescents showed significant positive relationships with BMD measured in young adulthood (vitamin D measured at the lumbar spine; calcium measured at the femoral neck). The positive relationship between vitamin D and BMD remained significant at young adulthood, but at the femoral neck rather than at the lumbar spine. Also in females, intakes of phosphorus and the calcium:phosphorus ratio (Ca:P) at adolescence were strongly negatively related to femoral neck BMD measured at young adulthood. In males, however, Ca:P reported at young adulthood had a significant positive relationship with lumbar spine BMD, whereas Ca:protein was negatively associated with BMD at the lumbar spine. Intakes of Ca reported by adolescent males also had a strong negative effect on lumbar spine BMD measured at young adulthood.

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-alpha1 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 Bal1. 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.

Socio-economic position and coronary heart disease risk factors in youth. Findings from the Young Hearts Project in Northern Ireland.

BACKGROUND: This study investigates the existence of socioeconomic differentials in behavioural and biological risk factors for coronary heart disease in young people from Northern Ireland, taking into account differences in biological maturation. METHODS: A school-based prospective study, with measurements in 1989/1990 and 1992/1993. Socio-economic position was based on occupational level of the main family breadwinner. Behavioural risk factors included were physical inactivity, the intake of total energy, dietary fat and a number of micronutrients. Biological risk factors included were blood pressure, body fatness, lipoproteins and cardio-pulmonary fitness. Biological maturation was based on Tanner's stages. PARTICIPANTS: 251 boys and 258 girls who were measured at the age of 12 years and re-examined at the age of 15 years. RESULTS: Cross-sectional analyses showed that socio-economic differences in cholesterol intake (in boys) and physical inactivity and total energy intake (in girls) were present at 12 and 15 years of age, while differences in fat and fruit intake and smoking behaviour (in boys and girls) became established at the age of 15 years, with unfavourable levels in subjects in the manual group. Longitudinal analyses confirmed that differences in behavioural risk factors exist or develop during adolescence. No clear pattern of differences in biological risk factors was found by socio-economic position. Adjustment for biological maturation did not materially alter the results. CONCLUSION: Differences in lifestyle by socio-economic position seem to become established in adolescence. These differences however, are not (yet) reflected in differences in biological risk factors by socio-economic position.

Birthweight and aerobic fitness in adolescents: the Northern Ireland Young Hearts Project.

The purpose of this study was to examine relationships between aerobic fitness and birthweight in adolescents. A representative cohort of 1015 males and females aged 12 and 15 y was studied, at baseline, with 89% of the 12-y-olds being re-examined 3 y later. The main outcome measures were an index of aerobic fitness, measured in laps completed at voluntary exhaustion by a twenty-metre shuttle run test, and recorded birthweight. Multiple linear regression, with and without adjustment for known and potential confounding variables, was performed to examine associations between fitness and birthweight. Birthweight and aerobic fitness were positively related so that for each kg decrease in birthweight, there was a mean (95% confidence interval) decrease in fitness score of 4.84 (0.35 to 9.33) laps and 3.21 (0.32 to 6.10) laps, in 12-y-old boys and girls respectively. This relationship is of a similar order to the strength of association between birthweight and adult blood pressure previously reported. Associations between birthweight and physical fitness at the age of 15 were weaker and were not significant. Our findings suggest that aerobic fitness may be involved in mediating the association between birthweight and cardiovascular disease risk later in life. The weakening of the association between birthweight and fitness between the ages of 12 and 15 y is similar to the weaker associations between birthweight and blood pressure seen among adolescents compared to younger children. We are currently re-examining this cohort to see if, as with blood pressure, the association with fitness re-emerges at an older age.

Tracking of nutrient intakes in adolescence: the experiences of the Young Hearts Project, Northern Ireland.

This study evaluated the tracking of energy and nutrient intakes, assessed by diet history, in a random sample of adolescents (boys n 225, girls n 230) at baseline (age 12 years), and subsequently at age 15 years. Median energy (MJ/d) and macronutrient (g/d) intakes increased significantly (all P < 0.001) with increasing age in the boys. The girls' reported energy intake (MJ/d) remained stable over time, despite significant increases in BMI, weight and % body fat. Age-related changes in the girls' macronutrient intakes were inconsistent. When expressed in terms of nutrient density, the diets of both sexes became significantly richer, over time, in total folate (both sexes, P < 0.01), but poorer in Ca (boys P < 0.01, girls P < 0.001) and riboflavin (both sexes P < 0.001). Vitamin B6 (P < 0.001) and Fe (P < 0.05) densities increased in the boys, while the thiamin density of the girls' diets decreased (P < 0.001). Tracking, defined as maintenance of rank over time, was summarised using weighted kappa statistics (kappa). There were some significant changes in intakes at the group level; however, tracking of energy and nutrients in both sexes was only poor to fair (kappa < 0.40), indicating substantial drift of individuals between classes of intake over time. Particularly poor tracking was evident for % energy from sugars (kappa 0.09) and total fat (kappa 0.09) in the girls' diets. In conclusion, the poor to fair tracking observed in this cohort suggests that individual dietary patterns exhibited at 12 years of age are unlikely to be predictive of energy and nutrient intake at age 15 years.

Training effects of accumulated daily stair-climbing exercise in previously sedentary young women.

BACKGROUND: The health and fitness benefits associated with short, intermittent bouts of exercise accumulated throughout the day have been seldom investigated. Stair climbing provides an ideal model for this purpose. METHODS: Twenty-two healthy female volunteers (18-22 years) were randomly assigned to control (N = 10) or stair-climbing (N = 12) groups. Stair climbers then underwent a 7-week stair-climbing program, progressing from one ascent per day in week 1 to six ascents per day in weeks 6 and 7, using a public access staircase (199 steps). Controls were instructed to maintain their normal lifestyle. Standardized stair-climbing tests were administered to both groups immediately before and after the program. Each paced ascent lasted 135 s, during which oxygen uptake (VO(2)) and heart rate (HR) were monitored continuously. Blood lactate concentration was also measured immediately following each test ascent. Fasting blood samples from before and after the program were analyzed for serum lipids. Data were analyzed using a two-way ANOVA with repeated measures. RESULTS: Relative to the insignificant changes in the control group, the stair-climbing group displayed a rise in HDL cholesterol concentration (P<0.05) and a reduced total:HDL ratio (P<0.01) over the course of the program. VO(2) and HR during the stair-climbing test were also reduced, as was blood lactate (all P<0.01). CONCLUSION: A short-term stair-climbing program can confer considerable cardiovascular health benefits on previously sedentary young women, lending credence to the potential public health benefits of this form of exercise.