Waist circumference cut-off values for the prediction of cardiovascular risk factors clustering in Chinese school-aged children: a cross-sectional study

BACKGROUND

Waist circumference has been identified as a valuable predictor of cardiovascular risk in children. The development of waist circumference percentiles and cut-offs for various ethnic groups are necessary because of differences in body composition. The purpose of this study was to develop waist circumference percentiles for Chinese children and to explore optimal waist circumference cut-off values for predicting cardiovascular risk factors clustering in this population.

METHODS

Height, weight, and waist circumference were measured in 5529 children (2830 boys and 2699 girls) aged 6-12 years randomly selected from southern and northern China. Blood pressure, fasting triglycerides, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and glucose were obtained in a subsample (n = 1845). Smoothed percentile curves were produced using the LMS method. Receiver-operating characteristic analysis was used to derive the optimal age- and gender-specific waist circumference thresholds for predicting the clustering of cardiovascular risk factors.

RESULTS

Gender-specific waist circumference percentiles were constructed. The waist circumference thresholds were at the 90th and 84th percentiles for Chinese boys and girls respectively, with sensitivity and specificity ranging from 67% to 83%. The odds ratio of a clustering of cardiovascular risk factors among boys and girls with a higher value than cut-off points was 10.349 (95% confidence interval 4.466 to 23.979) and 8.084 (95% confidence interval 3.147 to 20.767) compared with their counterparts.

CONCLUSIONS

Percentile curves for waist circumference of Chinese children are provided. The cut-off point for waist circumference to predict cardiovascular risk factors clustering is at the 90th and 84th percentiles for Chinese boys and girls, respectively.

Associations among body size dissatisfaction, perceived dietary control, and diet history in African American and European American women

European American (EA) women report greater body dissatisfaction and less dietary control than do African American (AA) women. This study investigated whether ethnic differences in dieting history contributed to differences in body dissatisfaction and dietary control, or to differential changes that may occur during weight loss and regain. Eighty-nine EA and AA women underwent dual-energy X-ray absorptiometry to measure body composition and completed questionnaires to assess body dissatisfaction and dietary control before, after, and one year following, a controlled weight-loss intervention. While EA women reported a more extensive dieting history than AA women, this difference did not contribute to ethnic differences in body dissatisfaction and perceived dietary control. During weight loss, body satisfaction improved more for AA women, and during weight regain, dietary self-efficacy worsened to a greater degree for EA women. Ethnic differences in dieting history did not contribute significantly to these differential changes. Although ethnic differences in body image and dietary control are evident prior to weight loss, and some change differentially by ethnic group during weight loss and regain, differences in dieting history do not contribute significantly to ethnic differences in body image and dietary control.

Low-fat oxidation may be a factor in obesity among men with schizophrenia

OBJECTIVE

Obesity associated with atypical antipsychotic medications is an important clinical issue for people with schizophrenia. The purpose of this project was to determine whether there were any differences in resting energy expenditure (REE) and respiratory quotient (RQ) between men with schizophrenia and controls.

METHOD

Thirty-one men with schizophrenia were individually matched for age and relative body weight with healthy, sedentary controls. Deuterium dilution was used to determine total body water and subsequently fat-free mass (FFM). Indirect calorimetry using a Deltatrac metabolic cart was used to determine REE and RQ.

RESULTS

When corrected for FFM, there was no significant difference in REE between the groups. However, fasting RQ was significantly higher in the men with schizophrenia than the controls.

CONCLUSION

Men with schizophrenia oxidised proportionally less fat and more carbohydrate under resting conditions than healthy controls. These differences in substrate utilisation at rest may be an important consideration in obesity in this clinical group.

Increased strength and decreased flexibility are related to reduced oxygen cost of walking

Purpose was to determine effects resistance training/weight loss induced changes in muscular strength and flexibility have on net walking oxygen uptake (netVO(2)). Sixty-seven premenopausal women lost 12 kg. Before weight loss subjects were assigned to diet (WL) or diet/3 days per week resistance training (WLRT). Resting energy expenditure, oxygen uptake while walking at 4.84 km h(-1) on the flat and up 2.5% grade, isometric knee extension strength, and flexibility of the knee extensors and plantar flexors were measured. Strength increased in WLRT (+36 N) but not in WL (-24 N). NetVO(2) decreased significantly while flat walking (7.3%) and 2.5% grade walking (5.7%) in WLRT, but not in WL. Delta strength was negatively while delta knee extensor and plantar flexor flexibility were positively related to delta netVO(2). Decreases in walking and grade netVO(2) were independently and positively related to increased knee extension strength and decreased knee extensor and plantar flexor flexibility.

Are Japanese criteria for obesity useful for screening at risk Japanese? Consideration from anthropometric indices-percentage body fat relationships

Both childhood and adult obesity are of serious public health concern in Japan. While Japan has diagnostic criteria for both childhood and adult obesity and metabolic syndrome, the appropriateness of the proposed criteria has been questioned. The present study aimed to determine screening ability of anthropometric indices relative to estimated percentage body fat (% BF) and to propose gender- and maturation-specific cut-off points using 1,393 Japanese (552 males and 841 females; 7.6-66.3 years old). Between 20%-50% of individuals with high fat deposits were misclassified using body mass index (BMI), abdominal circumference (AC), abdominal to height ratio (AHtR), and sum of two skinfolds (Sigma2SF). Using the WHO public action point of 23 kg/m2, AC of 80 cm, AHtR of 0.5 for all groups and Sigma2SF of 25 mm for males and 40 mm for females were estimated to be potentially useful cut-off points. The results may indicate a need for further research for appropriate screening cut-off points for Japanese.

Bioelectric impedance is a better indicator of obesity in men with schizophrenia than body mass index

Body mass index (BMI) is commonly used as an indicator of obesity, although in both clinical and research settings the use of bioelectric impedance analysis (BIA) is commonplace. The purpose of this study was to examine the relationship between BMI, BIA and percentage body fat to determine whether either is a superior indicator of obesity in men with schizophrenia. The reference method of deuterium dilution was used to measure total body water and, subsequently, percentage body fat in 31 men with schizophrenia. Comparisons with the classification of body fat using BMI and BIA were made. The correlation between percentage body fat and BMI was 0.64 whereas the correlation between percentage body fat and BIA was 0.90. The sensitivity and specificity in distinguishing between obese and overweight participants was 0.55 and 0.80 for BMI and 0.86 and 0.75 for BIA. BIA proved to be a better indicator of obesity than BMI. BMI misclassified a large proportion of men with schizophrenia as overweight when they had excess adiposity of sufficient magnitude to be considered as obese. Because of the widespread use of BMI as an indicator of obesity among people with schizophrenia, the level of obesity among men with schizophrenia may be in excess of that previously indicated.

Resistance training conserves fat-free mass and resting energy expenditure following weight loss

OBJECTIVE

To determine what effect diet-induced approximately 12 kg weight loss in combination with exercise training has on body composition and resting energy expenditure (REE) in premenopausal African-American (AA) and European-American (EA) women.

METHODS AND PROCEDURES

This study was a longitudinal, randomized weight loss clinical intervention, with either aerobic (AT), resistance (RT), or no exercise training (NT). Forty-eight AA and forty-six EA premenopausal overweight (BMI between 27 and 30) women underwent weight loss to a BMI<25. Body composition (densitometry), REE (indirect calorimetry), maximal oxygen uptake (VO2max), and muscular strength (isometric elbow flexion) were evaluated when subjects were in energy balance.

RESULTS

AA women lost less fat-free mass (FFM, P<or=0.05) (47.0+/-4.6 to 46.9+/-5.0 kg) than EA women (46.4+/-4.9 to 45.2+/-4.6 kg). Regardless of race, RT maintained FFM (P<or=0.05) following weight loss (46.9+/-5.2 to 47.2+/-5.0 kg) whereas AT (45.4+/-4.2 to 44.4+/-4.1 kg) and NT (47.9+/-4.7 to 46.4+/-5.1 kg) decreased FFM (P<or=0.05). Both AT and NT decreased in REE with weight loss but RT did not. Significant time by group interactions (all P<or=0.05) for strength indicated that RT maintained strength and AT did not.

DISCUSSION

AA women lost less FFM than EA women during equivalent weight losses. However, following weight loss in both AA and EA, RT conserved FFM, REE, and strength fitness when compared to women who AT or did not train.

Combined effect of body position, apparatus and distraction on children's resting metabolic rate

OBJECTIVE

To verify the combined effect of body position, apparatus and distraction on children's resting metabolic rate (RMR).

METHODS

Experiments were carried out on 14 children aged 8-12 (mean age = 10.1 years +/- 1.4). Each participant underwent two test sessions, one week apart under three different situations: a) using mouthpiece and nose-clip (MN) or facemask (FM); b) sitting (SEAT) or lying (LY); and c) TV viewing (TV) or no TV viewing. In the first session, following 20 min rest and watching TV, the protocol was: LY: 20 min stabilization; 10 min using MN and 10 min using FM. Body position was then changed to seated: 20 min stabilization; 10 min using FM; 10 min using MN. In the second session, FM and MN order was changed and participants did not watch TV. Data were analysed according to the eight combinations among the three studied parameters.

RESULTS

Repeated measures ANOVA indicated statistically significant differences for VO2 (p =0.01) and RMR (p =0.02), with TVMNSEAT showing higher values than TVFMLY. Bland-Altman analysis showed a bias for VO2, VCO2, respiratory quotient (RQ) and RMR between TVFMLY and TVMNSEAT, respectively, of -17.8+/-14.5 (ml min), -8.8+/-14.5 (ml min), 0.03+/-0.05 and -115.2+/-101.9 (kcal/day).

CONCLUSION

There were no differences in RMR measurements due to body position and apparatus when each variable was isolated. Analyses of distraction in three of four combinations indicated no difference between TV and no TV. Different parameter combinations can result in increased bias and variability, and thereby the reported differences among children's RMR measurement.

Variability in adherence to an unsupervised exercise prescription in obese women

OBJECTIVE

To measure adherence to a specific exercise prescription (1500 kcal week(-1)) by objectively quantifying unsupervised exercise energy expenditure (ExEE) in obese women.

DESIGN

The 16-week lifestyle intervention consisted of weekly meetings with research staff and promotion of increased ExEE (1500 kcal week(-1)) and a decreased dietary intake (-500 kcal day(-1)).

PARTICIPANTS

Twenty-nine obese females (body mass index=36.8+/-5.0 kg m(-2), body fat=49.6+/-3.7%) from a hospital-based lifestyle intervention were included in the analysis.

MEASUREMENTS

ExEE was estimated and monitored weekly using heart rate monitoring, and body composition was measured before and after the intervention by dual-energy X-ray absorptiometry.

RESULTS

Free-living adherence to the exercise prescription was variable and, on average, modest such that 14% achieved 1500 kcal week(-1), and the average weekly ExEE (768 kcal week(-1)) represented 51.2% of the total amount prescribed. ExEE was correlated with changes in body weight (r=0.65, P<0.001) and fat mass (r=0.65, P<0.001). Achievement of a 5% weight loss target was dependent on the achievement of an ExEE level of 1000 kcal week(-1) (P<0.001). Exercise 'adherers' (>1000 kcal week(-1)) lost more weight (-9.9 vs -4.1 kg), more fat mass (-6.8 vs -3.0 kg) and more waist circumference (-9.8 vs -5.6 cm) when compared to 'non-adherers' (<1000 kcal week(-1)).

DISCUSSION

Exercise is an integral component of lifestyle interventions aimed at reducing obesity and its complications. However, without accurate and objective measures of ExEE, it is difficult for relationships between exercise and health outcomes to be elucidated. The present study suggests an alternative to self-report to increase the confidence with which conclusions are drawn regarding the role of exercise within lifestyle interventions.

Comparison of clinical body composition methods in people taking weight-inducing atypical antipsychotic medications

The purpose of this study was to compare the accuracy of clinical methods to estimate body fat (%BF) in people who take weight-inducing atypical antipsychotic medications. Forty-seven people (35 males, 12 females) with previously diagnosed psychotic illness who had been taking atypical antipsychotic medications for more than 6 months took part in this study. Percentage body fat was estimated using bioelectrical impedance analysis (BIA) and anthropometry from previously published prediction equations and compared with that measured using the deuterium dilution technique which served as the criterion measure. Bland-Altman analyses were used to assess the agreement between measures. In the males, %BF determined using BIA with the Lukaski equation was the only clinical method with mean differences that were not significant from criterion values. While in the females, %BF determined from BMI was the only method that was significantly different from the criterion values. All of the methods of estimating %BF except Watson equations provided consistent estimates across the weight range. Therefore, this study suggests that in a group of people who predominantly had schizophrenia and were taking atypical antipsychotic medications, BIA using the equation of Lukaski was the best indicator of %BF, although on an individual basis the accuracy was poor. BMI underestimated %BF to a greater significant extent than BIA. The use of BIA rather than BMI may provide a better indicator of adiposity in people who take weight inducing antipsychotic medications.

Effect of stage duration on physiological variables commonly used to determine maximum aerobic performance during cycle ergometry

In this study, we examined the effect of stage duration on physiological variables commonly used to determine maximum aerobic performance during cycle ergometry. Ten recreationally trained males (mean age 27.8 +/- 7.1 years; BMI 24.3 +/- 2.5 kg x m(-2); VO2max 52.5 +/- 5.9 ml x kg(-1) x min(-1)) performed three different stage duration protocols on two separate occasions. Each short stage (SS; 1-min stages), long stage (LS; 3-min stages), and constant load + short stage (CL + SS; 4-min constant load followed by 1-min stages) protocol started at 50 W with increments of 30 W. The physiological variables measured included: time to maximum, maximum workload, maximum oxygen consumption (VO2max), maximum heart rate, maximum rating of perceived exertion, maximum blood lactate concentration, and maximum respiratory exchange ratio. The ventilatory threshold was calculated for every trial of the three protocols. There was no difference in VO2max, but maximum heart rate was higher in the LS protocol (P<0.05). Maximum respiratory exchange ratio varied between the protocols (P<0.05), while maximum workload differed between the SS and LS protocols, and the LS and CL + SS protocols (P<0.0001). The physiological variables were comparable between trials for the SS and CL + SS protocols, but maximum workload and VO2max differed for the LS protocol (P<0.05). Workload at the ventilatory threshold was lower for the LS protocol (P<0.05). Heart rate at the ventilatory threshold was different between the LS and CL + SS protocols (P<0.05). Performing a test involving 1- or 3-min stage durations on a single occasion was appropriate for the determination of VO2max and the ventilatory threshold. However, the disparity in heart rate and workload could result in differences in mechanical and physiological work being undertaken. Consistent use of a protocol may alleviate errors during exercise prescription.

Validation of a three-frequency bioimpedance spectroscopic method for body composition analysis

OBJECTIVE

We assessed whether whole-body multiple frequency impedance (MFBIA) data obtained at a few discrete frequencies could be used to estimate accurately resistance at 0 (R(0)) and infinite (R(infinity)) frequencies required for prediction of body composition by mixture theory.

METHODS

Fat-free mass (FFM) was measured in 157 subjects (77 males, 80 females; body mass index [BMI] 17.8-41.7 kg/m(2)) by dual X-ray absorptiometry (DXA). Whole-body impedance was measured and R(0) and R(infinity) were calculated by three different methods. FFM predicted using the different values of R(0) and R(infinity) were compared with each other and with the reference DXA values for all subjects stratified according to BMI band (BMI <24.9 kg/m(2), normal weight; BMI 25-29.9 kg/m(2), overweight; BMI >30 kg/m(2), obese).

RESULTS

All BIA procedures predicted an FFM that was slightly but significantly different from DXA-derived values, underestimating by 0.24 to 1.4 kg in the normal-weight subjects and overestimating by 5.3 to 7.1 kg in the obese subjects. Although statistically significant, the different impedance procedures were highly correlated (r > 0.98), with small limits of agreement (approximately +/-2%) when used to predict FFM. Predictive power was associated with BMI, worsening as BMI increased.

CONCLUSION

MFBIA can be used to estimate impedance parameters required for mixture theory prediction of body composition, but this approach requires adjustment for BMI to be accurate.

Metabolic and behavioral compensatory responses to exercise interventions: barriers to weight loss

An activity-induced increase in energy expenditure theoretically disturbs energy balance (EB) by creating an acute energy deficit. Compensatory responses could influence the weight loss associated with the energy deficit. Individual variability in compensation for perturbations in EB could partly explain why some individuals fail to lose weight with exercise. It is accepted that the regulatory system will readily defend impositions that promote a negative EB. Therefore, a criticism of exercise interventions is that they will be ineffective and futile methods of weight control because the acute energy deficit is counteracted. Compensation for exercise-induced energy deficits can be categorized into behavioral or metabolic responses and automatic or volitional. An automatic compensatory response is a biological inevitability and considered to be obligatory. An automatic compensatory response is typically a metabolic consequence (e.g., reduced resting metabolic rate) of a negative EB. In contrast, a volitional compensatory response tends to be deliberate and behavioral, which the individual intentionally performs (e.g., increased snack intake). The purpose of this review is to highlight the various metabolic and behavioral compensatory responses that could reduce the effectiveness of exercise and explain why some individuals experience a lower than expected weight loss. We propose that the extent and degree of compensation will vary between individuals. That is, some individuals will be predisposed to compensatory responses that render them resistant to the weight loss benefits theoretically associated with an exercise-induced increase in energy expenditure. Therefore, given the inter-individual variability in behavioral and metabolic compensatory responses, exercise prescriptions might be more effective if tailored to suit individuals.

Resistance training improves metabolic economy during functional tasks in older adults

The purpose of this study was to determine the effect resistance training has on metabolic economy during typical activities of daily living in a geriatric population. Twenty-nine men and women (age: 66.7 +/- 4.4 years, body mass: 72.3 +/- 11.9 kg) participated in a 26-week heavy-resistance training program. Before and after training, heart rate and expiratory gases were measured for subjects performing 3 tasks that would mimic common everyday activities encountered by this population: (a) walking (WLK) at 3 miles per hour (4.8 km x h(-1)), (b) carrying a box (CAR) to simulate holding a bag of groceries with 1 hand (30% of maximal isometric strength) while walking at 2 miles per hour (3.2 km x h(-1)), and (c) climbing stairs (STR). No time by gender interaction was observed for the WLK, CAR, and STR activities; consequently, the values for men and women were pooled. Both strength and fat-free mass increased significantly (p < or = 0.001) after the training protocol, whereas body mass remained constant. Oxygen cost decreased significantly by 6% (p < or = 0.05) only for CAR, whereas the respiratory exchange ratio decreased significantly (p < or = 0.05) for both WLK (0.84-0.81) and STR (0.87-0.83), and heart rate decreased significantly (p < or = 0.05) only for CAR. After the resistance training program, subjects also reported a significant decrease (p < or = 0.05) in perceived exertion during performance of all functional task test conditions. These results suggest that a heavy-resistance training program might affect exercise economy during daily tasks and improve ease of physical activity, thereby providing a possible mechanism for increasing quality of life in an older and geriatric population.

Minimizing random error in dietary intakes assessed by 24-h recall, in overweight and obese adults

OBJECTIVE

To determine the minimum number of days of dietary intake interviews required to reduce the effects of random error (day-to-day variability in dietary intake) when using the multiple-pass, multiple-day, 24-h recall method.

DESIGN

Cross-sectional study.

SETTING

University research department.

SUBJECTS

A total of 50 healthy non-smoking overweight and obese (body mass index=26-40 kg/m2) adult men and women aged 39-45 years completed the study. Participants were randomly selected from volunteers for a larger unrelated study.

INTERVENTIONS

Each participant completed 10, multiple-pass, 24-h recall interviews on randomly chosen days over 4 weeks. The minimum number of record days was determined for each macronutrient (carbohydrate, fat, protein) and energy, for each gender, to obtain a 'true' (unobservable) representative intake from reported (observed) dietary intakes.

RESULTS

The greatest number of days required to obtain a 'true' representative intake was 8 days. Carbohydrate intakes required the greatest number of days of dietary record among males (7 days), whereas protein required the greatest number of days among females (8 days) in this cohort. Sunday was the day of the week that showed greatest variability in macronutrient intakes. Protein (P<0.05) and fat (P<0.001) intakes were significantly more variable than carbohydrate on Sundays compared with weekdays, for both men and women.

CONCLUSION

A logistically achievable 8 days of dietary intake interviews was sufficient to minimize the effect of random error when using the multiple-pass, 24-h recall dietary intake method. Sunday should be included among the dietary interview days to ensure a 'true' representation of macronutrient intakes. This method can be confidently applied to small cohort studies in which dietary intakes from different groups are to be compared or to investigations of associations between nutrient intakes and disease.

Implications of the variability in time to isotopic equilibrium in the deuterium dilution technique

OBJECTIVE

To investigate the variability in isotopic equilibrium time under field conditions, and the impact of this variability on estimates of total body water (TBW) and body composition.

DESIGN AND SETTING

Following collection of a fasting baseline urine sample, 10 women and 10 men were dosed with deuterium oxide (0.05 g/kg body weight). Urine samples were collected every hour for 8 h. The samples were analysed using isotope ratio mass spectrometry. Time to equilibration was determined using three commonly employed data analysis approaches.

RESULTS

Isotopic equilibrium was reached by 50, 80 and 100% of participants at 4, 6 and 8 h, respectively. The mean group equilibration determined using the three different plateau determination methods were 4.8+/-1.5, 3.8+/-0.8 and 4.9+/-1.4 h. Isotopic enrichment, TBW, and percent body fat estimates differed between early (3-5 h), but not later sampling times (5-8 h).

CONCLUSION

Although the three different plateau determination approaches resulted in differences in equilibration time, all suggest that sampling at 6 h or later will decrease the likelihood of error in body composition estimates resultant from incomplete isotopic equilibration in a small proportion of individuals.

Day-to-day variance in measurement of resting metabolic rate using ventilated-hood and mouthpiece & nose-clip indirect calorimetry systems

BACKGROUND

To know if the magnitude of change in resting metabolic rate (RMR) observed during an intervention is meaningful, it is imperative to first identify the variability that occurs within individuals from day to day under normal conditions. The 2 most common systems used to measure RMR involve a ventilated hood or a mouthpiece & nose clip to collect expired gases. The variation in measurement using these 2 approaches has not been systematically compared.

METHODS

RMR was measured in 10 healthy adults during 5 separate testing sessions within a 2-week period where usual diet and physical activity were maintained. Each testing session consisted of one measurement of RMR using a ventilated hood system, followed by another using a mouthpiece & nose-clip system.

RESULTS

No significant difference in RMR was evident between measurement sessions using either indirect calorimeter. Oxygen consumption and RMR were significantly higher using the mouthpiece & nose-clip system. Average within-individual coefficient of variation for RMR was significantly lower for the ventilated-hood system. RMR measures were consistently lower using the ventilated-hood system by an average of 94.5 +/- 63.3 kcal. Day-to-day variance was between 2% and 4% for both systems.

CONCLUSIONS

The use of either system is appropriate for assessing RMR in clinical and research settings, but alternating between systems should be undertaken with caution. A change in RMR must be greater than approximately 6% (96 kcal/d; 1.2 kcal/kg/d) or approximately 8% (135 kcal/d; 1.7 kcal/kg/d) when using a ventilated-hood system or a mouthpiece & nose-clip system, respectively, to observe any meaningful intervention-related differences within individuals.

Effect of weight loss due to lifestyle intervention on subclinical cardiovascular dysfunction in obesity (body mass index >30 kg/m2)

Subclinical myocardial and vascular dysfunctions occur in subjects with obesity. We investigated whether these changes were reversible with weight loss due to lifestyle intervention. Quantitative assessment of myocardial and vascular functions was performed at baseline and after a minimum of 8 weeks of a lifestyle intervention program in 106 subjects with significant risk factors but no history of cardiovascular disease and normal ejection fractions. Myocardial function was assessed using strain rate, strain, regional myocardial systolic velocity, and diastolic velocity (e(m)). Myocardial reflectivity was assessed by calibrated integrated backscatter. Vascular function was assessed using brachial arterial reactivity and arterial compliance. Exercise capacity was measured by peak oxygen consumption per unit time (VO(2)). Weight loss (-4.5 +/- 2.0%) was achieved by 48 subjects, and 58 maintained or increased weight (+1 +/- 1.5%, p <0.001). Compared with the stable weight group, the weight loss group showed significant improvement in brachial arterial reactivity (8.6 +/- 4.9% vs 6.7 +/- 4.9%, p <0.05), e(m) (6.4 +/- 1.9 vs 5.5 +/- 1.9 cm/s, p <0.01), and reflectivity (calibrated integrated backscatter, 18.3 +/- 4.9 vs 16.2 +/- 5.2 dB, p <0.01). The magnitude of weight change correlated with changes in e(m) (r = 0.36) and calibrated integrated backscatter (r = 0.33). The change in e(m) correlated with peak VO(2) (r = 0.38, p <0.001) and was an independent predictor for peak VO(2) even after adjustment for age and body mass index in a multivariate model (R(2) = 0.45, p <0.001). Weight loss was not associated with a significant change in systolic parameters (regional myocardial systolic velocity, global strain, and strain rate) or arterial compliance.

Increased resting energy expenditure after 40 minutes of aerobic but not resistance exercise

OBJECTIVE

Resting energy expenditure (REE) is increased 24 hours after high-intensity aerobic exercise lasting 60 minutes, whereas results have been inconsistent after resistance training and aerobic exercise of shorter duration. The objective of the study was to compare the effects of 40 minutes of high-intensity aerobic vs. resistance exercise on REE 19 to 67 hours after exercise.

RESEARCH METHODS AND PROCEDURES

REE was compared 19, 43, and 67 hours after 40 minutes of aerobic training (AT; 80% maximum heart rate) or resistance training (RT; 10 repetitions at 80% maximum strength, two sets and eight exercises). Twenty-three black and 22 white women were randomly assigned to AT, RT, or no training (controls). Exercisers trained 25 weeks. REE was measured after a 12-hour fast.

RESULTS

There was a significant time x group interaction for REE when adjusted for fat-free mass and fat mass, with post hoc tests revealing that the 50-kcal difference between 19 and 43 hours (1310 +/- 196 to 1260 +/- 161 kcal) and the 34-kcal difference between 19 and 67 hours (1310 +/- 196 to 1276 +/- 168 kcal) were significant for AT. No other differences were found, including RT (19 hours, 1256 +/- 160; 43 hours, 1251 +/- 160; 67 hours, 1268 +/- 188 kcal). Urine norepinephrine increased with training only in AT. After adjusting for fat-free mass, REE Delta between 19 and both 43 and 67 hours was significantly related to urine norepinephrine (r = 0.76, p < 0.01 and 0.68, p < 0.03, respectively).

DISCUSSION

Consistent with findings on longer duration AT, these results show that 40 minutes of AT elevates REE for 19 hours in trained black and white women. This elevation did not occur with 40 minutes of RT. Results suggest that differences are, in part, due to increased sympathetic tone.

Weight loss strategies for obese adults: personalized weight management program vs. standard care

OBJECTIVE

The objective of this study was to evaluate the effect of a 32-week personalized Polar weight management program (PWMP) compared with standard care (SC) on body weight, body composition, waist circumference, and cardiorespiratory fitness in overweight or obese adults.

RESEARCH METHODS AND PROCEDURES

Overweight or obese (29 +/- 2 kg/m(2)) men and women (n = 74) 38 +/- 5 years of age were randomly assigned into either PWMP (men = 20, women = 21) or SC (men = 15, women = 18). Both groups managed their own diet and exercise program after receiving the same standardized nutrition and physical activity advice. PWMP also received a weight management system with literature to enable the design of a personalized diet and exercise weight loss program. Body weight and body composition, waist circumference, and cardiorespiratory fitness were measured at weeks 0, 16, and 32.

RESULTS

Eighty percent of participants completed the 32-week intervention, with a greater proportion of the dropouts being women (PWMP: 2 men vs. 7 women; SC: 2 men vs. 4 women). At 32 weeks, PWMP completers had significantly (p < 0.001) greater losses in body weight [6.2 +/- 3.4 vs. 2.6 +/- 3.6 (standard deviation) kg], fat mass (5.9 +/- 3.4 vs. 2.2 +/- 3.6 kg), and waist circumference (4.4 +/- 4.5 vs. 1.0 +/- 3.6 cm). Weight loss and fat loss were explained by the exercise energy expenditure completed and not by weekly exercise duration.

DISCUSSION

More effective weight loss was achieved after treatment with the PWMP compared with SC. The results suggest that the PWMP enables effective weight loss through tools that support self-monitoring without the requirement of more costly approaches to program supervision.

Energy expenditure and physical activity in clozapine use: implications for weight management

OBJECTIVE

The management of atypical antipsychotic-induced weight gain is a significant challenge for people with mental illness. Fundamental research into energy metabolism in people taking atypical antipsychotic medication has been neglected. The current study of men with schizophrenia taking clozapine aimed to measure total energy expenditure (TEE) and energy expended on physical activity--activity energy expenditure (AEE) and to consider the clinical implications of the findings.

METHOD

The well-established reference method of doubly labelled water (DLW) was used to measure TEE and AEE in men with schizophrenia who had been taking clozapine for more than 6 months. Resting energy expenditure was determined using indirect calorimetry.

RESULTS

The TEE was 2511+/-606 kcal day-1 which was significantly different to World Health Organization recommendations (more than 20% lower). The Physical activity level (PAL) was 1.39+/-0.27 confirming the sedentary nature of people with schizophrenia who take clozapine.

CONCLUSIONS

The findings support the need for weight management strategies for people with schizophrenia who take clozapine to focus on the enhancement of energy expenditure by increasing physical activity and reducing inactivity or sedentary behaviours, rather than relying primarily on strategies to reduce energy intake.

Musculoskeletal disorders associated with obesity: a biomechanical perspective

Despite the multifactorial nature of musculoskeletal disease, obesity consistently emerges as a key and potentially modifiable risk factor in the onset and progression of musculoskeletal conditions of the hip, knee, ankle, foot and shoulder. To date, the majority of research has focused on the impact of obesity on bone and joint disorders, such as the risk of fracture and osteoarthritis. However, emerging evidence indicates that obesity may also have a profound effect on soft-tissue structures, such as tendon, fascia and cartilage. Although the mechanism remains unclear, the functional and structural limitations imposed by the additional loading of the locomotor system in obesity have been almost universally accepted to produce aberrant mechanics during locomotor tasks, thereby unduly raising stress within connective-tissue structures and the potential for musculoskeletal injury. While such mechanical theories abound, there is surprisingly little scientific evidence directly linking musculoskeletal injury to altered biomechanics in the obese. For the most part, even the biomechanical effects of obesity on the locomotor system remain unknown. Given the global increase in obesity and the rapid rise in musculoskeletal disorders, there is a need to determine the physical consequences of continued repetitive loading of major structures of the locomotor system in the obese and to establish how obesity may interact with other factors to potentially increase the risk of musculoskeletal disease.

The impact of childhood obesity on musculoskeletal form

Despite the greater prevalence of musculoskeletal disorders in obese adults, the consequences of childhood obesity on the development and function of the musculoskeletal system have received comparatively little attention within the literature. Of the limited number of studies performed to date, the majority have focused on the impact of childhood obesity on skeletal structure and alignment, and to a lesser extent its influence on clinical tests of motor performance including muscular strength, balance and locomotion. Although collectively these studies imply that the functional and structural limitations imposed by obesity may result in aberrant lower limb mechanics and the potential for musculoskeletal injury, empirical verification is currently lacking. The delineation of the effects of childhood obesity on musculoskeletal structure in terms of mass, adiposity, anthropometry, metabolic effects and physical inactivity, or their combination, has not been established. More specifically, there is a lack of research regarding the effect of childhood obesity on the properties of connective tissue structures, such as tendons and ligaments. Given the global increase in childhood obesity, there is a need to ascertain the consequences of persistent obesity on musculoskeletal structure and function. A better understanding of the implications of childhood obesity on the development and function of the musculoskeletal system would assist in the provision of more meaningful support in the prevention, treatment and management of the musculoskeletal consequences of the condition.

The biomechanics of restricted movement in adult obesity

In spite of significant advances in the knowledge and understanding of the multi-factorial nature of obesity, many questions regarding the specific consequences of the disease remain unanswered. In particular, there is a relative dearth of information pertaining to the functional limitations imposed by overweight and obesity. The limited number of studies to date have mainly focused on the effect of obesity on the temporospatial characteristics of walking, plantar foot pressures, muscular strength and, to a lesser extent, postural balance. Collectively, these studies have implied that the functional limitations imposed by the additional loading of the locomotor system in obesity result in aberrant mechanics and the potential for musculoskeletal injury. Despite the greater prevalence of musculoskeletal disorders in the obese, there has been surprisingly little empirical investigation pertaining to the biomechanics of activities of daily living or into the mechanical and neuromuscular factors that may predispose the obese to injury. A better appreciation of the implications of increased levels of body adiposity on the movement capabilities of the obese would afford a greater opportunity to provide meaningful support in preventing, treating and managing the condition and its sequelae. Moreover, there is an urgent need to establish the physical consequences of continued repetitive loading of major structures of the body, particularly of the lower limbs in the obese, during the diverse range of activities of daily living.

Quantification of lean bodyweight

BACKGROUND

Lean bodyweight (LBW) has been recommended for scaling drug doses. However, the current methods for predicting LBW are inconsistent at extremes of size and could be misleading with respect to interpreting weight-based regimens.

OBJECTIVE

The objective of the present study was to develop a semi-mechanistic model to predict fat-free mass (FFM) from subject characteristics in a population that includes extremes of size. FFM is considered to closely approximate LBW. There are several reference methods for assessing FFM, whereas there are no reference standards for LBW.

PATIENTS AND METHODS

A total of 373 patients (168 male, 205 female) were included in the study. These data arose from two populations. Population A (index dataset) contained anthropometric characteristics, FFM estimated by dual-energy x-ray absorptiometry (DXA - a reference method) and bioelectrical impedance analysis (BIA) data. Population B (test dataset) contained the same anthropometric measures and FFM data as population A, but excluded BIA data. The patients in population A had a wide range of age (18-82 years), bodyweight (40.7-216.5 kg) and BMI values (17.1-69.9 kg/m2). Patients in population B had BMI values of 18.7-38.4 kg/m2. A two-stage semi-mechanistic model to predict FFM was developed from the demographics from population A. For stage 1 a model was developed to predict impedance and for stage 2 a model that incorporated predicted impedance was used to predict FFM. These two models were combined to provide an overall model to predict FFM from patient characteristics. The developed model for FFM was externally evaluated by predicting into population B.

RESULTS

The semi-mechanistic model to predict impedance incorporated sex, height and bodyweight. The developed model provides a good predictor of impedance for both males and females (r2 = 0.78, mean error [ME] = 2.30 x 10(-3), root mean square error [RMSE] = 51.56 [approximately 10% of mean]). The final model for FFM incorporated sex, height and bodyweight. The developed model for FFM provided good predictive performance for both males and females (r2 = 0.93, ME = -0.77, RMSE = 3.33 [approximately 6% of mean]). In addition, the model accurately predicted the FFM of subjects in population B (r2 = 0.85, ME = -0.04, RMSE = 4.39 [approximately 7% of mean]).

CONCLUSIONS

A semi-mechanistic model has been developed to predict FFM (and therefore LBW) from easily accessible patient characteristics. This model has been prospectively evaluated and shown to have good predictive performance.

State of the science: a focus on physical activity

Diet, exercise, behavioural support and for some obese individuals, pharmacotherapy, represent the set of lifestyle factors necessary for effective management of obesity. An on-going challenge in the prevention, treatment and management of obesity is to arm health professionals in particular, with the necessary knowledge and understanding and time to engage in meaningful weight management counseling. Despite the many barriers to effective management such as lack of relevant education in nutrition and physical activity, perceived patient non-compliance, perceived inability to change patient behaviours, and the cost of specialist behavioural support, there is increasing evidence of the value of behaviour modification techniques to both dietary and exercise counseling, particularly when focusing on current behaviour. Behavioural counseling addresses the barriers to compliance with diet and physical activity goals and also equips the individual with practical strategies and motivation to be more self-responsible. Commonly employed behavioural interventions include stimulus control, reinforcement techniques, self-monitoring, behavioural contracting, and social support programs. This paper addresses one of the key behavioural components in the treatment and management of obesity - physical activity. Higher levels of energy expenditure through increased physical activity are central to successful weight loss and long-term weight maintenance. The specific value derived from physical activity in the context of weight management for the overweight and obese is in large part associated with an appreciation of the role of both physical activity promotion and exercise prescription.

Validation of the intensity of walking for pleasure in obese adults

BACKGROUND

Despite evidence that 'walking for pleasure' represents the most common leisure-time physical activity, the exercise intensity associated with 'walking for pleasure' in the obese has not been established.

METHODS

Heart rate (HR), perceived exertion (RPE) and walking speed were assessed for 30 obese and 20 non-obese adults as they completed two 2 km-walk tests on alternate days and were compared with a third 2 km walk with subjects walking 'as fast as possible'.

RESULTS

Despite both obese (O) and non-obese (NO) groups rating the intensity of 'walking for pleasure' as 'light', HR and RPE data for only the NO group complied with definitions of 'light' intensity effort. 'Walking for pleasure' was characterised by a higher absolute (15 bpm, P < 0.05) and relative (70% of predicted maximum, P < 0.01) HR in the O group, which was representative of the transition between 'moderate' and 'hard' intensity exercise. The findings in the third, maximal trial were comparable across groups for all variables.

CONCLUSION

Adiposity exerts a relative elevation-of-intensity effect on the cardiovascular system at walking speeds consistent with 'walking for pleasure'. 'Walking for pleasure' is sufficient to improve cardiovascular fitness in obese, but not normal-weight, individuals.

Physical activity and nutritional status of children of low socioeconomic status. Two interrelated problems: undernutrition and overweight

The aim of this study was to analyse the level of habitual physical activity (HPA) and nutritional status of children attending selected public schools in Brazil. The sample comprised 1719 participants who ranged in age from 11 to 14 yrs with 861 females (F) aged 12.7+/-1.0 yr and 858 males (M) aged 12.7+/-1.0 yr. The short form of the International Physical Activity Questionnaire (IPAQ) was used to measure HPA. Nutritional status was assessed using the body mass index (BMI). Statistical analyses included ANOVA followed by the post-hoc Tukey-test (P<0.05) which showed a statistically significant difference between M and F in time spent in moderate intensity physical activity. F completed more moderate intensity physical activity than M whereas time in vigorous physical activities was higher in M than F. Analyses of BMI and IPAQ categorical score using Pearson product moment correlations with subsequent Fisher Z transformation showed values of Z = 0.49 for females and Z = 0.44 for males, indicating a low relationship between these variables. HPA levels showed 93.7% of the M and 91.1% of the F were at least minimally active. According to BMI values, 7.3% of the cohort was underweight; 83.0% normal weight; 8.3% overweight and 1.3% obese. These results demand attention, particularly for children at the lower end of nutritional status and HPA levels due to the potential negative impact on their growth and development. At the other end of the nutritional spectrum, one needs to be concerned regarding the levels of excess body weight, mainly considering the poor region in which the children live.

Metabolic equivalent: one size does not fit all

The metabolic equivalent (MET) is a widely used physiological concept that represents a simple procedure for expressing energy cost of physical activities as multiples of resting metabolic rate (RMR). The value equating 1 MET (3.5 ml O2·kg−1·min−1 or 1 kcal·kg−1·h−1) was first derived from the resting O2 consumption (V̇o2) of one person, a 70-kg, 40-yr-old man. Given the extensive use of MET levels to quantify physical activity level or work output, we investigated the adequacy of this scientific convention. Subjects consisted of 642 women and 127 men, 18–74 yr of age, 35–186 kg in weight, who were weight stable and healthy, albeit obese in some cases. RMR was measured by indirect calorimetry using a ventilated hood system, and the energy cost of walking on a treadmill at 5.6 km/h was measured in a subsample of 49 men and 49 women (26–45 kg/m2; 29–47 yr). Average V̇o2 and energy cost corresponding with rest (2.6 ± 0.4 ml O2·kg−1·min−1 and 0.84 ± 0.16 kcal·kg−1·h−1, respectively) were significantly lower than the commonly accepted 1-MET values of 3.5 ml O2·kg−1·min−1 and 1 kcal·kg−1·h−1, respectively. Body composition (fat mass and fat-free mass) accounted for 62% of the variance in resting V̇o2 compared with age, which accounted for only 14%. For a large heterogeneous sample, the 1-MET value of 3.5 ml O2·kg−1·min−1 overestimates the actual resting V̇o2 value on average by 35%, and the 1-MET of 1 kcal/h overestimates resting energy expenditure by 20%. Using measured or predicted RMR (ml O2·kg−1·min−1 or kcal·kg−1·h−1) as a correction factor can appropriately adjust for individual differences when estimating the energy cost of moderate intensity walking (5.6 km/h).

Community physiotherapy for children with cystic fibrosis: A family satisfaction survey

BACKGROUND AND PURPOSE

Input of a specialist physiotherapist is integral to the management of children with cystic fibrosis (CF). In recent years, many regional centres have developed specialist physiotherapy posts based in the community. The aim of this study was to ascertain the effectiveness of the community physiotherapy service in Newcastle upon Tyne, from the families' point of view.

METHODS

The current service was reviewed and a questionnaire was developed and sent to all families with a child/children attending the regional paediatric centre for full care. It was adapted from a standardised patient satisfaction survey and included both open and closed questions.

RESULTS

One hundred and six questionnaires were sent with a response rate of 50%. Eighty-nine percent of respondents had been reviewed by the community physiotherapist. Ninety-one percent were satisfied with the overall service provided. They felt involved in the treatment plan (94%) and understood the reasons for follow up visits (92%). Eighty-five percent of respondents had a contact number for the community physiotherapist. Comments from parents were generally positive. Many families requested increased input in the home as they found it more beneficial than review in the clinic setting.

CONCLUSIONS

There was a high rate of satisfaction with specialist physiotherapy support in the community for children with CF among families who responded to the patient satisfaction survey.

Resting energy expenditure is lower than predicted in people taking atypical antipsychotic medication

Resting energy expenditure (REE) is lower than predicted in persons taking atypical antipsychotic medication, and weight management is a significant clinical challenge for some of them. However, to date there have been no published guidelines to assist clinicians in choosing appropriate prediction equations to estimate energy expenditure in persons taking atypical antipsychotic medications. The objectives of this study were to measure REE in a group of men taking the atypical antipsychotic clozapine and to determine whether REE can be accurately predicted for this population using previously published regression equations. REE was measured using indirect calorimetry via a ventilated hood on eight men who had completed at least 6 months of treatment with clozapine. Comparisons between measured REE and predicted REE using five different equations were undertaken. The commonly-used Harris-Benedict and Schofield equations systematically overestimated REE. Predictions of REE from other equations were too variable for clinical use. When estimating energy requirements as part of a weight-management program in men who have been taking clozapine for 6 months, predictions of REE from the equations of Harris-Benedict and Schofield should be reduced by 280 kcal/day.

Use of [14C]-sodium bicarbonate/urea to measure physical activity induced increases in total energy expenditure in free-living healthy males

The aim of this study was to evaluate the utility of the [(14)C]-sodium bicarbonate/urea technique to detect physical activity-induced increases in total energy expenditure in free-living healthy men. Thirteen healthy males aged 34.1 +/- 11.7 yrs with body mass index 24.1 +/- 3.1 kg/m(2) were studied on three separate occasions, during which [(14)C]-bicarbonate was infused over 48-hours and urine was collected during the second 24-hours. On three separate occasions and in random order, subjects either remained sedentary, or performed a bout of physical activity on an electro-magnetically braked cycle ergometer sufficient to increase energy expenditure by 7% or 11% above predicted sedentary total energy expenditure. Urine samples were analyzed to evaluate the amount of [(14)C]-bicarbonate incorporated into urinary urea, thereby reflecting the amount of CO(2) produced per day, and upon conversion, the number of kilojoules of energy expended in 24-hours. All 13 subjects successfully completed the two physical activity treatments and there were no adverse events. As measured by the [(14)C]-urea assay, mean total energy expenditure values were not significantly different between sedentary activity (17902 +/- 905 kJ/day), the physical activity treatment designed to increase TEE by 7% (17701 +/- 594 kJ/day) and the physical activity treatment designed to increase TEE by 11% (18538 +/- 485 kJ/day) (P=0.668). In conclusion, although the [(14)C]-sodium bicarbonate/urea technique was well tolerated and did not interfere with normal daily activities, it was not able to accurately measure physical activity-induced increases in EE in the range of 7-11% above predicted sedentary total energy expenditure.

Influences of ethnicity and socioeconomic status on the body dissatisfaction and eating behaviour of Australian children and adolescents

The present study examined the association between socioeconomic status (SES), ethnicity, body dissatisfaction, and eating behaviours of 10- to 18-year-old children and adolescents. The study participants (N = 768) were categorised as Caucasian (74.7%), Chinese or Vietnamese (18.2%), and Italian or Greek (7.0%), and high (82%), middle (8.6%), and low SES (9.4%) according to parents' occupations. The chi(2), Mann-Whitney U test and Kruskal-Wallis test and logistic regression model were used to determine the interaction between variables. Females and older participants were more likely to desire a body figure that was thinner than their perceived current figure. Furthermore, the same groups were also more likely to be preoccupied with eating problems (females 7.1% vs. males 1.4%; for participants aged 15-18 years, 7.8% vs. participants aged 10-14 years, 3.9%). The body dissatisfaction gender difference was females 42.8% vs. males 11.8%, and participants aged 15-18 years 41.7% vs. those aged 10-14 years, 28.3%. Participants whose parents were managers/professionals were more likely to desire a body figure that was thinner than their perceived current figure than those from white-collar and blue-collar families. This was also the case for Caucasian Australians compared to those from Chinese or Vietnamese backgrounds. In conclusion, age and gender differences in body image and problems in eating behaviour were evident among children and adolescents. However, there was no significant SES and ethnic difference in the proportion of participants with eating problems and body dissatisfaction.

Physical Activity and Muscle Function but Not Resting Energy Expenditure Impact on Weight Gain

Understanding whether metabolic factors are predictive of weight gain is important for developing strategies for prevention of weight gain. Recent research has shown that sleeping and resting energy expenditure are not predictive of weight gain. However, exercise endurance, muscular strength, (31)P MRS muscle metabolic economy, and maximum oxygen uptake are independently related to weight gain. Activity-related energy expenditure and the time spent in physical activity are also related to weight gain, with low physical activity explaining approximately 77% of weight gain at 1 year. In addition, weight maintainers spend 80 minutes per day, whereas weight gainers spend less than 20 minutes per day in physical activity equivalent to an intensity of about 4 METS. It is proposed that strength, aerobic fitness, and physical activity are important factors for reducing the rate of weight gain. Although further research is required, these results are suggestive that weight maintenance programs will be more successful if some relatively high-intensity training is included to complement large amounts of low to moderate intense physical activity.

The arch index: a measure of flat or fat feet?

BACKGROUND

Studies using footprint-based estimates of arch height have indicated that obesity results in a lowered medial longitudinal arch in children. However, the potentially confounding effect of body composition on indirect measures of arch height, such as the arch index, has not been investigated.

METHODS

This study assessed the body composition of 12 male and 12 female adults (mean age: 39.9 +/- 8.1 years, height: 1.724 +/- 0.101 m; weight: 95.1 +/- 13.7 kg, and BMI: 31.9 +/- 3.0 kg/m(2)) using bioelectrical impedance analysis to produce a two-component model of fat mass (FM) and fat-free mass (FFM). The dynamic arch index also was determined from electronic footprints captured during gait using a capacitive pressure distribution platform with a resolution of 4 sensors/cm(2).

RESULTS

While significant correlations were noted between FFM and the area of both the hindfoot (r =.75, p <.05) and forefoot (r =.72, p <. 05), the midfoot area was correlated only with FM (r =.54, p <.05). Similarly, the arch index was significantly correlated with the FM percentage (r =.67, p <.05).

CONCLUSIONS

The findings of this pilot study suggest that body composition influences arch index values in overweight and obese subjects. Consequently, body composition may be a confounding factor in interpreting footprint based estimates of arch height and, as such, these estimates would best be used with supplementary measures of body composition.

Physical activity in the management of obesity

Physical activity is any movement of skeletal muscles that results in energy expenditure. Long-term success in weight management depends on both physical activity and dietary modification. Exercise has a pivotal role in weight management, optimising body composition by minimising fat-free mass losses and maximising fat mass loss; and, enhancing metabolic fitness. The amount and type of exercise needed to obtain health-related benefits may differ from that recommended for fitness benefits. Public health messages about exercise have focused on improvements in general health and fitness rather than on weight loss, prevention of weight gain or weight regain. About 2.5 times more exercise than the US Surgeon General's recommendation is needed to maintain energy balance and thus maintain a certain weight. The challenge is to get the exercise prescription right at an individual level.

Comparison of lung deposition of colomycin using the HaloLite and the Pari LC Plus nebulisers in patients with cystic fibrosis

AIM

To examine the effectiveness of delivery of nebulised colistin by the HaloLite nebuliser compared to the Pari LC Plus in patients with cystic fibrosis.

METHODS

Randomised crossover trial of 15 patients aged >6 years. Inhalation of one mega unit of colistin in 3 ml diluent, labelled with technetium-99m DTPA, was used to assess lung deposition. The Pari was nebulised to dryness and one button press of the HaloLite was completed. Following a seven day washout period, patients inhaled colistin twice daily for seven days through the first device. Sputum specimens were analysed for colistin levels and pseudomonas load. This procedure was repeated with the alternative device.

RESULTS

Lung uptake of radiolabelled colistin was significantly higher with the Pari. However, lung uptake calculated as a percentage of the amount of drug used was significantly higher for the HaloLite. Time to nebulise was significantly shorter with the HaloLite. Sputum levels of colistin were higher following use of the Pari; this was close to significance.

CONCLUSION

The manufacturer's recommended dosages for nebulising antibiotics with a HaloLite result in a lower delivery than patients receive when using a Pari nebuliser. The concept of adaptive aerosol delivery has several theoretical advantages but the recommended doses for the HaloLite need to be modified in order to improve effectiveness.

Influence of distribution of lean body mass on resting metabolic rate after weight loss and weight regain: comparison of responses in white and black women

BACKGROUND

Little is known about the effect of weight change on regional lean body mass (LBM) distribution or on racial differences in resting metabolic rate (RMR).

OBJECTIVE

The study compared total and regional LBM patterns in white and black women after weight loss and regain and assessed the influence of regional LBM on variances in RMR.

DESIGN

Eighteen white and 22 black women who did not differ in age, weight, and height were studied 3 times: in the overweight state, after weight reduction to the normal-weight state, and after 1 y without intervention. Total and regional lean and fat masses were assessed by dual-energy X-ray absorptiometry.

RESULTS

White and black women did not differ significantly in mean (+/- SD) weight loss (13.4 +/- 3.6 and 12.7 +/- 3.2 kg, respectively) and regain (6.1 +/- 5.5 and 6.4 +/- 5.4 kg, respectively). Black subjects had significantly less trunk LBM and significantly more limb LBM at each time point (P < 0.05). In both races, weight regain was associated with significant increases in limb LBM (P < 0.05) but not in trunk LBM (P = 0.21). RMR, adjusted for total LBM and fat mass, was significantly higher in white women after weight loss (P < 0.01) and regain (P < 0.01). However, no racial difference was found when RMR was adjusted for LBM distribution.

CONCLUSIONS

In both races, trunk LBM decreased with weight loss and remained lower, despite significant weight regain, which potentially reflected decreased organ mass. Regional LBM distribution explained the racial difference in RMR.

Relationships between HR and (.)VO(2) in the obese

PURPOSE

To enable more targeted exercise prescription for the obese, the purpose of this study was to consider relationships between relative indices of (.)VO(2peak), (.)VO(2)R, HR(peak), and HRR in a sample of obese adults. In particular, the study aimed to determine whether %HRR was equivalent to %(.)VO(2peak) or %(.)VO(2)R. A further aim was to evaluate whether the %(.)VO(2peak)-%HR(peak) relationship defined by the ACSM holds in the obese population, or whether there is a deviation in this relationship as is noted in individuals with low functional capacity. Finally, the study aimed to determine the degree of variability in relative workload relating to lactate threshold (LT).

METHODS

Thirty-two sedentary obese adults, 17 women and 15 men (42.1 +/- 9.6 yr; 37.4 +/- 5.7 kg.m) attended a testing session each week for 3 wk. The three sessions involved 1) familiarization with testing protocols; 2) graded treadmill tests to evaluate submaximal and peak cardiorespiratory capacity; and 3) assessment of body composition via deuterium dilution, and resting HR (HR(rest)) and oxygen consumption ((.)VO(2rest)) collected during assessment of resting metabolic rate (RMR) via a ventilated hood system.

RESULTS

The primary findings were that in the obese: 1) the %HR(peak)-%(.)VO(2peak) relationship was significantly greater than the ACSM recommendations, 2) the %HRR was equivalent with (.)VO(2)R not %(.)VO(2peak), and 3) exercise prescription at fixed percentages of (.)VO(2peak) or HR(peak) corresponded with wide ranges of exercise intensities in relation to LT.

CONCLUSIONS

The relationships between cardiorespiratory parameters defined in normal weight populations differ to some degree in the obese, and this has implications both for optimizing exercise intensity for weight loss and exercise adherence in obese adults.

Free-living activity energy expenditure in women successful and unsuccessful at maintaining a normal body weight

BACKGROUND

Although physical inactivity is believed to contribute to the rising prevalence of obesity, the role and magnitude of its contribution to weight gain are unknown.

OBJECTIVE

We compared total free-living activity energy expenditure (AEE) and physical activity level in women successful and unsuccessful at maintaining a normal body weight.

DESIGN

Premenopausal, generally sedentary women were studied at their normal weight and 1 y later after no intervention. Two groups were identified on the basis of extreme weight changes: maintainers (n = 27) had a weight gain of less-than-or-equal 3% of their initial body weight ( less-than-or-equal 2 kg/y) and gainers (n = 20) had a weight gain of >10% (>6 kg/y). At baseline and follow-up, evaluations were conducted during 4 wk of diet-controlled, energy-balance conditions. Free-living AEE and physical activity were assessed with the use of doubly labeled water, exercise energy economy and muscle strength with the use of standardized exercise tests, and sleeping EE and substrate utilization with the use of chamber calorimetry.

RESULTS

Maintainers lost a mean (plus minusSD) of 0.5 plus minus 2.2 kg/y and gainers gained 9.5 plus minus 2.1 kg/y. Gainers had a lower AEE (P < 0.02), a lower physical activity level (P < 0.01), and less muscle strength (P < 0.001); these differences between groups remained significant from baseline to follow-up. Sleeping EE, exercise economy, and sleeping or 24-h substrate utilization were not significantly different between the 2 groups. A lower AEE in the gainers explained approximately 77% of their greater weight gain after 1 y.

CONCLUSION

The general US population should increase their daily physical activity levels to decrease the rising prevalence of obesity.

The biomechanics of adiposity--structural and functional limitations of obesity and implications for movement

Obesity is a significant health problem and the incidence of the condition is increasing at an alarming rate worldwide. Despite significant advances in the knowledge and understanding of the multifactorial nature of the condition, many questions regarding the specific consequences of the disease remain unanswered. For example, there is a dearth of information pertaining to the structural and functional limitations imposed by overweight and obesity. A limited number of studies to date have considered plantar pressures under the feet of obese vs. non-obese, the influence of foot structure on performance, gait characteristics of obese children and adults, and relationships between obesity and osteoarthritis. A better appreciation of the implications of increased levels of body weight and/or body fat on movement capabilities of the obese would provide an enhanced opportunity to offer more meaningful support in the prevention, treatment and management of the condition.

Exercise prescription for weight management

The debate surrounding the level of intensity of exercise that is best for health improvement has potentially clouded the issue of optimal exercise prescription for weight management. Low-intensity activity is potentially superior to moderate to high intensity for improving metabolic risk factors, and accumulated small bouts of physical activity are as effective to this end as single longer bouts, as long as the overall volume of energy expenditure is equivalent. What should not be forgotten however, is that for weight-loss it is the total volume of energy expended that will dictate the size of the energy deficit imposed, not the composition of the exercise per se. Exercise prescription for weight management is a conundrum. Whilst it is the total volume of energy expended that will dictate the magnitude of weight lost, not the composition of the exercise per se, it is the nature of the exercise prescription that will dictate the long-term success of an exercise programme. It is how well the exercise prescription is individualized that influences tolerance of and interest in the programme and, thus, the adherence to it in the long term.

Correlations of body composition and body-image assessments of adolescents

Body composition status influenced the strength of correlations between indices of body dissatisfaction assessed using a perceptual size-estimation method and two subjective measures of body image for 217 male ( n = 122) and female ( n = 95) adolescents.

Should body-image scales designed for adults be used with adolescents?

For many people, there is a discrepancy between perceived and desired physical appearance. Attempts have been made to quantify this discrepancy as a measure of body-image disturbance: however, the use of measurement scales which are not population-specific may bias the assessment. To investigate whether ratings of body-images were affected by the scale employed, 57 male and 40 female adolescents were tested using both adult and adolescent body-figure silhouette scales. Significant between-scale differences were found, with adolescents displaying consistently lower body-image ratings when viewing adult as opposed to adolescent scales. In addition, between-sex differences in discrepancy scores and correlations between discrepancy scores and another measure of body satisfaction were significantly influenced by the scale employed. The results confirm the need for population-specific measurement scales and the implementation of standardised assessment procedures.