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Biomedical subjects

C Boreham

Publications and source records attributed to C Boreham.

At least 19 recordsLinked to original sources
PubMed2003

Carbonated soft drink consumption and bone mineral density in adolescence: the Northern Ireland Young Hearts project.

UNLABELLED: In an observational study of 1335 boys and girls aged 12 and 15 years, higher intakes of carbonated soft drinks (CSDs) were significantly associated with lower bone mineral density at the heel, but only in girls. Owing to the upward trend in CSD intake in adolescence, this finding may be of concern. INTRODUCTION: High consumption of carbonated soft drinks (CSD) during adolescence may reduce bone mineral accrual and increase fracture risk. The aim of this study was to examine the relationship between CSD consumption and bone mineral density (BMD) in a representative sample of adolescents. MATERIALS AND METHODS: This was a cross-sectional observational study in 36 postprimary schools in Northern Ireland. Participants included 591 boys and 744 girls either 12 or 15 years old. BMD was measured by DXA, and usual beverage consumption was assessed by the diet history method. Adjusted regression modeling was used to investigate the influence of CSD on BMD. RESULTS: A significant inverse relationship between total CSD intake and BMD was observed in girls at the dominant heel (beta, -0.099; 95% CI, -0.173 to -0.025). Non-cola consumption was inversely associated with dominant heel BMD in girls (beta, -0.121; 95% CI, -0.194 to -0.048), and diet drinks were also inversely associated with heel BMD in girls (beta, -0.087; 95% CI, -0.158 to -0.016). However, no consistent relationships were observed between CSD intake and BMD in boys. Cola consumption and nondiet drinks were not significantly related to BMD in either sex. CONCLUSION: CSD consumption seems to be inversely related to BMD at the dominant heel in girls. It is possible that the apparent association results from the displacement of more nutritious beverages from the diet. Although the inverse association observed between CSD consumption and BMD is modest and confined to girls, this finding may have important public health implications given the widespread use and current upward trend in CSD consumption in Western populations.

Adolescent↗
PubMed2002

Associations between physical fitness and activity patterns during adolescence and cardiovascular risk factors in young adulthood: the Northern Ireland Young Hearts Project.

The aim of the present study was to examine relationships between cardiovascular disease (CVD) risk factor status in young adulthood (mean age = 22.5 yrs) and antecedent physical fitness and physical activity at ages 12 and 15 years. The data were obtained from the Young Hearts Project, a longitudinal observational study of CVD risk factors in a representative sample of young people from Northern Ireland. Physical fitness was measured by the 20-metre endurance shuttle run, and physical activity and sports participation by a self-report recall questionnaire. CVD risk factors examined included serum total cholesterol (TC) and HDL cholesterol concentrations, the TC:HDL ratio, systolic and diastolic blood pressure and body fatness (sum of four skinfolds). Linear regression analyses showed modest relationships between physical fitness in adolescence and both TC:HDL ratio and body fatness in young adulthood. No such relationships were apparent for adolescent physical activity. The promotion of physical fitness during adolescence may reduce exposure to other risk factors lasting into early adulthood.

Adolescent↗
PubMed2001

The physical activity, fitness and health of children.

It is clear that, despite their natural tendencies, children have become less physically active in recent decades, with children today expending approximately 600 kcal days' less than their counterparts 50 years ago. Although the health consequences of a reduced energy expenditure in adults is well documented, there is little direct evidence linking sedentariness with health in children. However, three main benefits arising from adequate childhood physical activity have been postulated. The first is direct improvements in childhood health status; evidence is accumulating that more active children generally display healthier cardiovascular profiles, are leaner and develop higher peak bone masses than their less active counterparts. Secondly, there is a biological carry-over effect into adulthood, whereby improved adult health status results from childhood physical activity. In particular, childhood obesity may be a precursor for a range of adverse health effects in adulthood, while higher bone masses in young people reduce the risk of osteoporosis in old age. Finally, there may be a behavioural carry-over into adulthood, whereby active children are more likely to become more active (healthy) adults. However, supporting evidence for this assertion is weak. Given this background, recent health guidelines suggesting that children should accumulate 60 min of moderate-intensity physical activity every day--supplemented by regular activities that promote strength flexibility and bone strength--appear to be justified. Future developments should include the implementation of large-scale, longitudinal studies spanning childhood and young adulthood, the further refinement of tools for measuring physical activity accurately in young people, and research into the relative strength of association between fitness--as well as activity--and health in children.

Energy Metabolism↗
PubMed2001

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.

Adipose Tissue↗
PubMed2000

Parental recall of birthweight: a good proxy for recorded birthweight?

Recent evidence suggests potential associations between birthweight and disease in later life. For resource or other reasons recorded birthweight may be unavailable to researchers who have access to uniquely relevant outcome data. The present study examined the validity of parental recall of birthweight. Parents of 1015 males and females aged 12 and 15 years participating in the Young Hearts Study (a cluster random sample of 1015 males and females aged 12 and 15 years from post-primary schools in Northern Ireland) completed a questionnaire which included a question about their child's birthweight. The answer provided was compared with recorded birthweight obtained from archived computerised child health records with a cut-off point for inaccurate reporting set at +/- 227 g (1/2 lb). The influence of social class and weight at birth on accuracy of recall was also determined. A total of 84.8% of parents accurately recalled their child's birthweight to within 227 g. Parents from non-manual occupation social classes recalled birthweight more accurately than those from manual occupation social classes (88.0 vs. 82.6% accurate: chi2 = 4.81, p = 0.03). Parents of low birthweight infants tended to recall their birthweight less accurately than parents of normal weight infants: 76.1% accurate compared to 86.1% accurate: chi2 = 3.54, p = 0.06. Parents of high birthweight infants recalled their birthweight less accurately than parents of normal weight infants: 78.5% accurate: chi2 = 3.94, p = 0.05. In conclusion, parentally recalled birthweight may be a suitable proxy for recorded birthweight for population based research into disease in childhood and adolescence.

Adolescent↗
PubMed1999

Relationships between the development of biological risk factors for coronary heart disease and lifestyle parameters during adolescence: The Northern Ireland Young Hearts Project.

The purpose of this study was to examine relationships between the longitudinal development of biological risk factors for coronary heart disease (CHD) (namely, serum lipids, body fatness, blood pressure and cardiorespiratory fitness) and the development of lifestyles considered to be atherogenic. The study was conducted in a representative sample of adolescents from Northern Ireland, a region of high coronary mortality, and atherogenic aspects of lifestyle such as cigarette smoking, physical inactivity and selected aspects of diet were examined. Repeated measurements were made at 12 and 15 y of age on 229 boys and 230 girls. Longitudinal relations were analysed with generalised estimating equations, and the following longitudinal relations were found: for boys diastolic blood pressure was positively associated with vitamin C intake (P = 0.014), and inversely with energy intake (P = 0.006), and smoking (P = 0.048). Systolic blood pressure was inversely related to physical activity (P = 0.012), and smoking (P = 0.000). Body fatness was also inversely related to smoking (P = 0.006). Total cholesterol (TC) was positively related to physical activity (P = 0.044) and the TC:HDL cholesterol ratio positively to vitamin C intake (P = 0.008). Cardiorespiratory fitness was positively related to physical activity (P = 0.000) and inversely to smoking (P = 0.031). For girls, systolic blood pressure was positively related to vitamin C intake (P = 0.042); HDL cholesterol inversely to carbohydrate intake (P = 0.014), fat intake (P = 0.031), cholesterol intake (P = 0.042) and smoking (P = 0.035) and positively to energy intake (P = 0.035). The TC:HDL cholesterol ratio was inversely related to energy intake (P = 0.038) and finally, cardiorespiratory fitness positively to physical activity (P = 0.001). These results offer additional evidence that changes in lifestyle are associated with changes in biological risk factors in adolescents. Education and intervention at this stage, particularly in relation to cigarette smoking, physical activity and certain aspects of diet appear justified as part of a preventative strategy for CHD.

Adolescent↗
PubMed1999

Clustering of biological risk factors for cardiovascular disease and the longitudinal relationship with lifestyle of an adolescent population: the Northern Ireland Young Hearts Project.

OBJECTIVE: To determine whether clustering of biological cardiovascular disease (CVD) risk factors exists and to investigate the longitudinal relationship between lifestyle parameters (dietary intake, physical activity and smoking behaviour) and clustering of biological CVD risk factors, which was defined as belonging to one or more sex-specific 'high-risk' quartiles for the ratio between levels of total serum cholesterol and high-density lipoprotein cholesterol, diastolic blood pressure, body fatness (sum of four skinfolds) and cardiopulmonary fitness (number of laps accomplished on a 20 m shuttle-run test). METHODS: The study was part of the Northern Ireland Young Hearts Project, a 3-year observational longitudinal study concerning adolescent boys (n=229) and girls (n=230) who were initially aged 12 years. The longitudinal relationships were analysed with generalized estimating equations. RESULTS: Significant clustering of biological CVD risk factors was observed both for boys and for girls, but the stability over time was rather low. Smoking was the only lifestyle parameter related to this clustering and was observed only among girls (rate ratio 1.5, P < 0.01); furthermore, none of the lifestyle parameters was significantly related to this clustering. CONCLUSIONS: Because biological CVD risk factors tend to cluster, it is important to investigate these risk factors together. However, for subjects in this age group, according to our analysis, lifestyle parameters were hardly related to this clustering.

Adolescent↗
PubMed1996

Nutrient intakes and impact of fortified breakfast cereals in schoolchildren.

OBJECTIVE: To report micronutrient intakes in Northern Ireland schoolchildren, and to establish the contribution of fortified breakfast cereal to overall nutrient intakes and achievement of current dietary recommendations. DESIGN: Analysis of dietary intakes and physical characteristics of participants in a randomly selected 2% population sample of 1015 schoolchildren aged 12 and 15 years in Northern Ireland during the 1990/1 school year. MAIN OUTCOME MEASURES: Dietary intakes, physical characteristics, and their association with consumption of fortified breakfast cereal. RESULTS: Mean micronutrient intakes were generally adequate with the exception of low intakes of folate (boys and girls) and iron (girls). Fortified breakfast cereals, consumed by a high proportion (94% boys; 83% girls) of the sample, were associated with higher daily intakes of most micronutrients and fibre and with a macronutrient profile consistent with current nutritional recommendations. Appreciable proportions of subjects who did not consume fortified breakfast cereals had daily intakes that fell below the lower reference nutrient intake for riboflavin, niacin, folate, vitamin B-12, and iron (girls). CONCLUSIONS: The results demonstrate the potential of fortification in contributing to micronutrient intakes of schoolchildren, particularly where requirements are high, or for those on marginal diets of low nutritional quality.

Adolescent↗
PubMed1995

Circulating gastrointestinal hormone changes in marathon running.

The purpose of this study was to observe the effect of marathon running on the release of gastrointestinal hormones and whether these might be related to gastrointestinal disturbances in marathon runners. Vasoactive intestinal polypeptide, gastrin, secretin, pancreatic polypeptide, neurokinin A, pancreastatin, insulin and glucagon-like peptide 1 were measured before, immediately upon finishing and 30 min after the race. Twenty-six competitors of the 1992 Belfast Marathon volunteered for this study. They had a mean age of 37 years and a mean finishing time of 239 min. Eight of the subjects complained of gastrointestinal distress during the race. The circulating concentration of all the GI hormones measured, except insulin were significantly elevated after the race. There was no significant change in glucose levels at the finish of the race. Statistical analysis revealed no direct relationship between the large increases in hormone levels and the occurrence of GI symptoms. These results show that GI hormone concentrations are affected by marathon running. Mechanisms of release and possible roles are discussed.

Adult↗
PubMed1995

Assessment of aerobic and anaerobic demands of dinghy sailing at different wind velocities.

The aim of this study was to assess the oxygen uptake (VO2), heart rate (HR) and blood lactate concentration ([Lab]) during actual dinghy sailing at different wind velocities. Eight top class Laser sailors volunteered to participate in the study. In the laboratory, each subject performed an incremental exercise test on a cycle ergometer to the point of exhaustion. Maximum oxygen uptake (VO2max) and maximum heart rate (HR max) were assessed by means of a Cosmed K2 (K2) portable oxygen analyser while the accuracy of the K2 was simultaneously examined by comparing it with the Douglas bag method. On water each subject underwent a 10 minute continuous upwind sailing test. The average percentages of VO2max and HR max during sailing and the post-test [La(b)] were 39 +/- 6%, 74 +/- 11% and 2.3 +/- 0.8 mM, respectively. Values of the three measured variables for each subject were significantly correlated to wind velocity (r = 0.73, 0.87 and 0.88, respectively). The results of the study suggest that the metabolic and cardiorespiratory demands of dinghy sailing predominantly depend on the wind conditions. Aerobic capacity is only moderately taxed in dinghy sailing and should not be emphasized in training, whereas anaerobic metabolism plays an increasing role in stronger winds.

Adult↗
PubMed1994

The effects of two different periods of weight-reduction on selected performance parameters in elite lightweight oarswomen.

Six successful members of the British Women's Lightweight Rowing Team were assessed before and after two-month (1990) and four-month (1991) periods of weight-reduction controlled by reduced caloric intake, while engaged in their normal physical training. Fat free mass (FFM) was calculated from body weight (BW) by utilising total body potassium measurements. Maximal oxygen intake (VO2max), respiratory anaerobic threshold (Tvent), upper body anaerobic peak power (PP) and mean power (MP) outputs, and knee flexor (KF) and extensor (KE) isokinetic peak torques were among the physiological parameters assessed. No statistical differences were noted between the data obtained prior to the two weight-reduction periods, and both periods resulted in lower BW (p < 0.001) and FFM (p < 0.05); approximately 50% of the lost BW was FFM. At the end of the two-month weight-reduction period Tvent (p < 0.02) and KF (p < 0.02) decreased. In contrast, a similar BW loss during the four-month period was associated with higher VO2max (p < 0.01) and PP (p < 0.05) compared with values prior to weight reduction. Comparisons between the percentage changes pre to post BW loss showed that the longer weight-reduction period was associated with significantly improved VO2max (p < 0.01), Tvent (p < 0.005), PP (p < 0.05) and KF (p < 0.05). We conclude: a) the proportion (50%) of weight lost as FFM in the present elite rowers is higher than the suggested optimal figure of 22%, and b) compared to four months, 6-7% of BW loss over two months may adversely influence fitness-related parameters in international lightweight oarswomen.

Adipose Tissue↗
PubMed1993

Coronary risk factors in schoolchildren.

Death rates from coronary heart disease (CHD) in Northern Ireland are among the highest in the world. However, no data have been available to test the hypothesis that the high prevalence of CHD is reflected by the risk status of the childhood population. A randomly selected 2% population sample of 1015 children aged 12 and 15 years was studied to obtain baseline information on blood pressure, lipid profile, cigarette smoking, family history, physical activity, cardiorespiratory fitness, and dietary fat intake. Using available criteria thresholds, 15-23% displayed increased blood pressure, 12-25% had unfavourable lipid profiles, and 18-34% were overfat. In 15 year old children, 16-21% admitted being regular smokers, 26-34% displayed poor cardiorespiratory fitness, and 24-29% reported little physical activity in the previous week. Dietary analysis revealed relatively low polyunsaturated to saturated fatty acid ratios and high mean fat intakes, accounting for approximately 40% total daily energy. Despite the exclusion of family history from the analysis, 16% of the older children exhibited three or more risk factors. These results justify major concern about the level of potential coronary risk in Northern Ireland schoolchildren. Broadly based primary prevention strategies aimed at children are essential if future adult CHD mortality is to be reduced.

Adolescent↗
PubMed1993

Seasonal variation of selected performance parameters in épée fencers.

In this study, anthropometric measurements were carried out on seven British international male épée fencers, using a maximal treadmill running test, a 20-s Wingate-type test, and isokinetic dynamometry. Testing was conducted on two occasions, 5 to 6 months apart, during mid-off-season (preparation) and mid-in-season (competition) periods. Maximal oxygen intake (VO2max) and maximal respiratory exchange ratio (Rmax) were among the parameters obtained from the treadmill test, while peak and mean anaerobic power outputs were measured during a 20-s maximal effort. Knee extensor and flexor muscle forces from both dominant (leading) and non-dominant (trailing) legs were assessed at 1.04, 3.14 and 4.19 rad sec-1. Statistical analyses revealed lower mean VO2max (P < 0.05) and mean Rmax values (P < 0.02) at the in-season assessments compared with off-season. In-season testing also demonstrated significantly lower peak torques for both dominant and non-dominant knee extensors compared with off-season assessments at all velocities (P < 0.05 to P < 0.004). Furthermore, in-season peak torque for the non-dominant leg flexors was lower (P < 0.03) at 4.19 rad sec-1 than off-season. We conclude that current training practices may account for the observed seasonal variations in performance related physiological parameters in fencers.

Adult↗
PubMed1992

Seasonal deterioration of selected physiological variables in elite male skiers.

The purpose of this study was to determine whether seasonal deterioration in physiological variables could be observed in skiers. Eighteen international male British downhill, free-style, and speed skiers were subjected to a maximal treadmill running test, a 30-s Wingate test, and isokinetic dynamometry at the beginning, middle, and end of the 1989-90 competition season. Maximal oxygen intake (VO2max) and respiratory anaerobic threshold (T vent) were among the parameters measured on the treadmill test, while peak and mean power outputs were measured during the Wingate test. During dynamometry, knee flexors and extensors were bilaterally assessed at 1.04 and 3.14 rad.s-1. Mean VO2max (p < 0.01) and mean T vent (p < 0.05) were lower at the end compared to the beginning, but not compared to the middle of the competition season. The isokinetic test demonstrated lower mean peak torques at 1.04 rad.s-1, for the knee extensors measured at the end of the season, compared with both the start (p < 0.01) and the middle (p < 0.05). Also at 1.04 rad.s-1, knee flexors produced lower torques at the end than the start of the season (p < 0.05). No further statistical differences were found. It was concluded that seasonal deterioration in key physiological variables such as aerobic endurance and muscle strength, can be observed in elite alpine skiers, and that in-season fitness training programmes should take account of this.

Anaerobic Threshold↗
PubMed1992

Growth hormone treatment of adults with growth hormone deficiency: results of a 13-month placebo controlled cross-over study.

OBJECTIVE: We aimed to study the effect of biosynthetic growth hormone (GH) replacement in growth hormone deficient adults. DESIGN: We performed a double-blind placebo-controlled cross-over study of 6 months biosynthetic GH, replacement and 6 months placebo separated by a 1-month's washout period. PATIENTS: Fourteen growth hormone deficient adults were studied. MEASUREMENTS: We measured total body weight, percentage fat mass, lean body mass, muscle volume, exercise capacity, maximum oxygen consumption, muscle strength, bone mineral content, a number of biochemical parameters, IGF-I, GH antibodies and psychological well-being. RESULTS: Total body weight remained unchanged, but lean body mass increased (before GH mean +/- SEM 49.8 +/- 5.5, after 53.4 +/- 5.6 kg; placebo before 51.2 +/- 5.4, after 50.4 +/- 5.1 kg; P less than 0.05 and fat mass decreased (before GH 21.5 +/- 4.1, after 19.3 +/- 4.3; placebo before 19.3 +/- 4.0, after 22.5 +/- 4.5 kg; P less than 0.05). Thigh muscle volume increased: (before GH 94.1 +/- 7.7, after 99.5 +/- 8.4 ml; placebo before 99.3 +/- 8.6, after 95.4 +/- 7.8 ml/0.8 mm computerized tomographic slice; P less than 0.05). Exercise capacity increased (before GH 174 +/- 15, after 199 +/- 18.9 watts; placebo before 162.5 +/- 2.3, after 154 +/- 19.8 watts; P less than 0.05), as did maximum oxygen consumption (before GH 1.93 +/- 0.2, after 2.17 +/- 0.2 l/m; placebo before 1.92 +/- 0.3, after 1.98 +/- 0.2 l/m; P less than 0.05). There was no change in quadriceps muscle strength. Alkaline phosphatase increased (before GH 87.5 (32-158), after 106.0 (49-179) U/I, placebo 99.5 (50-145), after 72.0 (40-111) U/I; P less than 0.05) without a change in the spinal bone density. IGF-I increased (before GH 62 (36-97), after 216 (62-362) micrograms/l; placebo before 59 (52-112), after 60.5 (38-94) micrograms/l; P less than 0.05). Carbohydrate tolerance remained unchanged as did fasting lipids, serum sodium, potassium, urea, calcium, phosphate and liver transaminases. Psychological well-being remained unchanged. No growth hormone antibodies were detected before or after GH treatment. CONCLUSIONS: GH alters the body composition of growth hormone deficient adults and leads to improved exercise capacity; alkaline phosphatase activity increases but without a change in spinal bone density, and carbohydrate tolerance remains unaltered.

Adult↗
PubMed1992

Insulin, glibenclamide or metformin treatment for non insulin dependent diabetes: heterogenous responses of standard measures of insulin action and insulin secretion before and after differing hypoglycaemic therapy.

Using carefully selected relatively non-obese non insulin dependent diabetic patients, we were not able to show differences in standard measures of insulin production or insulin action between patients treated with a long acting crystalline zinc insulin, with glibenclamide, or with metformin for a six week period. All three drugs were hypoglycaemic, but a fall in basal hepatic glucose output measured by the 3H3 glucose technique was only seen in those patients who had an initial fasting plasma glucose above 12.0 mmol/l, irrespective of treatment.

Blood Glucose↗
PubMed1992

Benefits of an exercise class for elderly women following hip surgery.

A prospective cohort study of a twice weekly exercise programme for six months was undertaken to determine the benefits of an exercise class for 28 elderly women following hip surgery. The effects of the exercise programme were monitored using cycle ergometry. Walking speed was measured on entry and at 3, 6 and 12 months. Twenty-six subjects completed the programme with an overall attendance rate of 88%. Measures of fitness, calculated from cycle ergometry, did not improve significantly apart from test duration. In contrast there was a significant improvement in mean walking speed, with a 50% increase between 0 and 3 months and a further 21% increase between 3 and 6 months. This improvement was maintained at 12 months.

Aged↗