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.

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.

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.

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.

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.

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.

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.

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.

Total radical trapping antioxidant potential (TRAP) and exercise.

The relationship between physical activity, physical fitness and total radical trapping antioxidant potential (TRAP) was examined in the Northern Ireland Health and Activity Survey. This was a cross-sectional population study (n = 1600) using a two-stage probability sample of the population. TRAP was calculated using the sum of the individual serum antioxidant concentrations (urate, protein thiols, ascorbate, alpha tocopherol and bilirubin) multiplied by their respective stoichiometric values. Physical fitness was determined by estimation of VO2max by extrapolation from submaximal oxygen uptake, and physical activity was recorded by computer-assisted interview. Mean serum TRAP concentrations were significantly higher in males (653 +/- 8.2 mumol/l, mean +/- SEM) compared to females (564 +/- 8.0 mumol/l) (p < 0.0001). Both male and female smokers had significantly lower TRAP values than non-smokers (males p < 0.0001, females p = 0.02). In females, there was a positive relationship of TRAP with age (p < 0.001) and body mass index (p < 0.001) but a negative relationship with physical fitness (p < 0.05). The known beneficial effects of exercise and activity do not appear to be directly mediated through increased antioxidant status.

Physical activity, physical fitness, blood pressure, and fibrinogen in the Northern Ireland health and activity survey.

STUDY OBJECTIVE: To investigate the relationship between physical activity, physical fitness, blood pressure, and fibrinogen. DESIGN: This was a cross sectional population study using a two stage probability sample. SETTING: Northern Ireland. PARTICIPANTS: A sample of 1600 subjects aged 16-74 years from the population of Northern Ireland. MAIN OUTCOME MEASURES: Physical activity profile from computer assisted interview using the Allied Dunbar national fitness survey scales. Physical fitness using estimation of VO2 max by extrapolation from submaximal oxygen uptake while walking on a motor driven treadmill. Systolic and diastolic blood pressure measured with a Hawksley random zero sphygmomanometer. Measurement of fibrinogen using the Clauss method. MAIN RESULTS: There were significant relationships between both current and past activity and blood pressure. These were of a magnitude that would have been clinically significant, but for the fact that, with the exception of the relationship between habitual activity and diastolic pressure (p = 0.03) and past activity and systolic pressure (p = 0.03) in men, they were not sustained after adjustment for the effect of age using analysis of variance. After adjustment for other potentially confounding factors using multiple regression, there was an inverse relationship between systolic blood pressure and past activity in men, so that those with a life-time of participation compared with a life-time of inactivity had a lower systolic blood pressure of 6 mmHg (p < 0.05). There was a highly significant (p < 0.001) inverse association between both systolic and diastolic blood pressure and physical fitness (VO2 max) which was not sustained after adjustment for possible confounding factors. There were relationships between fibrinogen and highest recorded activity (p < 0.001), habitual activity (p < 0.01), and past activity (p < 0.01) in men but no significant relationship in women. The relationship between fibrinogen and activity was no longer sustained after adjustment for possible confounding factors. There was a highly significant (p < 0.001) inverse relationship with physical fitness using VO2 max. This relationship was sustained after adjustment for possible confounding factors in both men (p < 0.05) and women (p < 0.001). CONCLUSIONS: There was a relationship between physical activity, physical fitness, and blood pressure but the relationship was greatly influenced by age. A reduction of 6 mmHg in systolic blood pressure associated with past activity is of clinical significance and supports the hypothesis that physical activity is of benefit in reducing cardiovascular risk. There was a lower level of fibrinogen in those who were most active but this relationship was not significant after adjustment for possible confounding factors. There was also a lower level of fibrinogen those who were most fit (VO2 max) and this relationship persisted even after adjustment for possible confounding factors.

The health-related physical activity of children.

The fitness and physical activity levels of children and youth are commonly questioned, but the evidence cited is both equivocal and methodologically diverse. The amount and type of physical activity undertaken during childhood that is appropriate for optimal health is unknown, although it has been suggested that, in the absence of such criteria, activity levels known to confer health benefits in adults are also appropriate for children. The measurement of activity in children is problematical, and there is currently no valid method of assessing activity levels that is feasible for use in large studies. Therefore, studies may lack either internal validity or wider applicability. Studies using self-report methods indicate relatively high levels of activity with 60 to 70% of children taking sufficient 'appropriate' physical activity. However, a variety of activity thresholds have been used. Studies that use more objective methods report much lower levels of activity, especially when cardiovascular fitness criteria are applied. The use of less stringent health-related thresholds results in higher levels of 'appropriate' activity. Nearly all studies of teenagers report a decline in activity with age during this period. Data from the large population studies indicate that activity levels peak in children at around 13 to 14 years of age, and then markedly decline. Boys are normally reported to be more active than girls, but this difference is greatly reduced when moderate activity alone is compared, indicating that boys participate in more vigorous exercise than girls. The health effects of low levels of vigorous activity in children are unclear.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

Physical fitness, lipids, and apolipoproteins in the Northern Ireland Health and Activity Survey.

The objective of this study was to investigate the relationship between physical fitness, lipids, and apolipoproteins in a cross-sectional study using a two-stage probability sample of the population of Northern Ireland. The main outcome measures were physical fitness using VO2max estimated by extrapolation from submaximal oxygen uptake while walking on a motor driven treadmill, and total cholesterol, HDL cholesterol, LDL cholesterol, triglycerides, HDL2 and HDL3, and Lp(a). There were no significant relationships with fitness, after adjustment for possible confounders, with the exception of a positive relationship with HDL2 in males (P < or = 0.01) and Lp(a) in females (P < or = 0.05). There was also a relationship between physical fitness and HDL:apo AI ratio in males and females after adjustment for possible confounders (P < or = 0.05). We concluded that there were few relationships between lipid parameters and physical fitness after adjustment for possible confounders. The relationship between physical fitness and Lp(a) in females suggests a benefit associated with physical fitness and the relationship between physical fitness and HDL:apo AI ratio was in keeping with improved HDL cholesterol transport.

Physical activity, lipids, apolipoproteins, and Lp(a) in the Northern Ireland Health and Activity Survey.

In a cross-sectional study using a two-stage probability sample (N = 1,600) of the population of Northern Ireland, there was an inverse association between the highest recorded recent activity and total cholesterol (P < or = 0.01), LDL (P < or = 0.01), triglyceride (P < or = 0.05) and Chol:HDL ratio (P < or = 0.001) in males, and total cholesterol (P < or = 0.001), LDL (P < or = 0.001), and triglyceride (P < or = 0.01) in females; between habitual activity and HDL (P < or = 0.05) in males and total cholesterol (P < or = 0.05) and triglyceride (P < or = 0.01) in females. There was a relationship between the highest recorded activity and apoAI (P < or = 0.01) and apoB (P < or = 0.01) in males and with apoB (P < or = 0.001) in females; between habitual activity and apoAI (P < or = 0.01) and apoAII (P < or = 0.05) in males and apoB (P < or = 0.01) in females; between past activity and Lp(a) in females (P < or = 0.05). After adjustment for possible confounding factors, total cholesterol (P < or = 0.05) and LDL (P < or = 0.05) were unexpectedly higher in males who were active throughout life. Total cholesterol (P < or = 0.05) and LDL (P < or = 0.001) were higher in females with highest recorded activity and triglycerides lower (P < or = 0.05) in those habitually active. An association between highest recorded activity and apoAI (P < or = 0.01), and past activity and apoAI:apoB ratio (P < or = 0.05) was shown in males and in females, after adjustment, and between apoB (P < or = 0.05) and highest recorded activity.

Vitamin E and exercise in the Northern Ireland population.

Serum vitamin E, vitamin E/cholesterol and physical activity and fitness were examined in a representative cross section (n = 1600) of the Northern Ireland population as part of the Northern Ireland health and activity survey. Serum vitamin E levels were measured by high-performance liquid chromatography, cholesterol by an enzymatic method, physical activity profile was recorded by computer assisted interview and physical fitness was determined by estimation of VO2 max. The levels of serum vitamin E and vitamin E/cholesterol ratio in the Northern Irish population were similar or higher than in other populations with lower incidences of coronary heart disease. The assessment of activity showed that 75% of the population fell below recommended activity levels likely to confer a cardioprotective effect. A significant relationship (P = 0.01) was found in males between serum vitamin E levels and lifetime participation in physical activity. Otherwise no relationship was found between serum vitamin E or vitamin E/cholesterol ratio and physical activity or fitness in the population.

Ascorbate and exercise in the Northern Ireland population.

The relationship between physical activity, physical fitness and serum ascorbate was examined in the Northern Ireland Health and Activity Survey. This was a cross sectional population study (n = 1600), using a two stage probability sample, of the population of N. Ireland. Physical activity profile was recorded by computer assisted interview and physical fitness was determined by estimation of VO2 max by extrapolation from submaximal oxygen uptake. Serum ascorbate was measured using a colorimetric reaction of 2,4 dinitrophenylhydrazine with dehydroascorbate. Mean serum ascorbate was greater in females than males (p < 0.001), and was lower in smokers than non-smokers in both males (p = 0.01) and females (p < 0.001). There was no statistically significant relationship between serum ascorbate and age, social class, body mass index, physical activity or physical fitness in males but there was a relationship with age (p < 0.01) and physical fitness (p < 0.05) in females.

A comparison of the PWC170 and 20-MST tests of aerobic fitness in adolescent schoolchildren.

The aim of this study was to compare the validity of two field tests of aerobic fitness for predicting maximal oxygen uptake (VO2max) in a group of adolescent schoolchildren. Twenty four schoolboys (means age = 15.6 +/- 0.6 yr) and twenty four schoolgirls (means age = 15.4 +/- 0.7 yr) underwent three different tests of aerobic capacity, with one week separating each assessment. The test were: (a) VO2max, using a continuous, progressive treadmill protocol, (b) a physical work capacity test at a heart rate of 170 beats per minute (PWC170), and (c) a 20-metre endurance shuttle run (20-MST), using a modified lapscoring protocol. Heart rates were monitored continuously in all tests. Results (means +/- SD) for boys n = 23) and girls (n = 18) respectively were: VO2max, 53.3 +/- 5.9 and 42.6 +/- 5.8 ml.kg-1.min-1; PWC170, 2.84 +/- 0.47 and 1.86 +/- 0.39 w.kg-1; 20-MST, 81.7 +/- 15.9 and 50.4 +/- 12.5 laps. Linear regression of PWC170 and 20-MST on VO2max scores (n = 41), revealed similarly high powers of prediction for both field tests (PWC170 vs VO2max, r = 0.84; 20-MST vs VO2max, r = 0.87), with an indication that the shuttle run test may be preferable for use with girls. In conclusion, the PWC170 and 20-MST field tests both appear to be valid predictors of VO2max in adolescent schoolchildren. However constraints of time and tester expertise favour the 20-MST for the assessment of aerobic capacity in the field.

Coronary risk factors in Belfast schoolchildren.

Although Northern Ireland leads the world in terms of coronary heart disease mortality, the prevalence of coronary risk factors in the childhood population is largely unknown. The aims of the present study were to assess the feasibility of collecting this data and to undertake a preliminary investigation of risk factor status. One hundred and three out of 154 first year pupils (67%), mean age 12.3 years from a Belfast secondary school had their height, weight, pubertal status and blood pressure estimated. Blood samples were analysed for serum cholesterol and thiocyanate in 99 children. 31% had elevated cholesterol, 13% had raised blood pressure, 13% were overweight and 5% were identified as smokers. There appeared to be relatively high risk factor levels with at least one risk factor present in 45% of children. No difficulties arose in compliance with the test protocol suggesting that coronary profiling in children on a large-scale is feasible. On the basis of these results, we feel that coronary risk factor status in Northern Irish children needs further evaluation.

The effect of minimal exercise on fitness in elderly women after hip surgery.

To determine the effect of minimal exercise on functional fitness following total hip replacement in elderly women, 20 women (13 exercisers, 7 controls) who had undergone unilateral or bilateral hip replacement surgery for primary osteoarthritis were studied. An exercise treadmill test with respiratory gas and blood lactate analyses, and a field test of walking speed on a measured course, were administered before and after a twice weekly exercise programme of three months' duration. Markers of cardiorespiratory fitness, including peak achieved oxygen uptake (VO2) and ventilatory and lactate thresholds were measured. Maximum self-selected walking speed was also measured over a flat course. Peak VO2 increased in the exercise group when compared to baseline (P < 0.05) but did not differ from the control group. The exercise group significantly improved their walking speed by 10.1% compared with non-exercising controls (1.41 vs 1.20 m/sec, P < 0.05), and increased VO2 at lactate threshold. The improvements occurred despite the twice weekly exercise sessions being below the recommended frequency of exercise for improving cardiorespiratory fitness. Minimal exercise in elderly women after hip surgery can substantially improve submaximal exercise capacity, as well as walking speed.