Clinically, gross obesity is associated with disturbances of ventilatory function, but less severe obesity is not generally thought to have a significant effect on ventilatory function. The purpose of this report was to examine cross-sectional data to determine the effects of body composition and fat distribution on ventilatory function in 1235 adults (621 men and 614 women). Forced vital capacity (FVC) was used as a measure of ventilatory function and was adjusted for age, height, smoking, and bronchial symptoms in separate models for men and women. Body fat and fat-free mass were estimated from skinfold-thickness measurements. Adjusted FVC was not significantly associated with body mass or body mass index, but was negatively associated with percentage body fat in men (P = 0.0003) and women (P = 0.043) and positively associated with fat-free mass in men (P = 0.018) and women (P = 0.0001). Handgrip strength was positively associated with adjusted FVC in both sexes (P < 0.02), suggesting that the effect of fat-free mass may be mediated by muscular strength. Adjusted FVC was negatively associated with subscapular-skinfold thickness in both sexes (P < 0.0003) and with waist circumference (P = 0.01) and waist-to-hip ratio (P = 0.03) in men. Previous reports that considered only body mass index or body mass failed to distinguish the opposing effects of fat-free mass and fat mass on FVC.

OBJECTIVE: Increasing physical activity is strongly advocated as a key public health strategy for weight gain prevention. We investigated associations of leisure-time physical activity (LTPA) and occupationaladomestic physical activity with body mass index (BMI) and a skinfold-derived index of body fat (sum of six skinfolds), among normal-weight and overweight men and women. DESIGN: Analyses of cross-sectional self-report and measured anthropometric data. SUBJECTS: A total of 1302 men and women, aged 18 ± 78 y, who were part of a randomly selected sample and who agreed to participate in a physical health assessment. MEASUREMENTS: Self-report measures of physical activity, measured height and weight, and a skinfold-derived index of body fatness. RESULTS: Higher levels of LTPA were positively associated with the likelihood of being in the normal BMI and lower body fat range for women, but few or no associations were found for men. No associations were found between measures of occupationaladomestic activity and BMI or body fat for men or women. CONCLUSION: By using a skinfold sum as a more direct measure of adiposity, this study extends and con®rms the previous research that has shown an association between BMI and LTPA. Our results suggest gender differences in the relationship of leisure-time physical activity with body fatness. These ®ndings, in conjunction with a better understanding of the causes of such differences, will have important public health implications for the development and targeting of weight gain prevention strategies. International Journal of Obesity (2001) 25, 914 ± 919

OBJECTIVE: Body mass index (BMI) based on self-reported height and weight is a systematically biased, but acceptable measure of adiposity and is commonly used in population surveys. Recent studies indicate that abdominal obesity is more strongly associated with obesity-related health problems than is adiposity measured by BMI. The purpose of this study was to determine the relationships of both measured and self-reported BMI with measured waist circumference in a randomly selected sample of Australian adults. DESIGN: Cross-sectional survey with self-reported and laboratory-based measures of adiposity. SUBJECTS: 1140 randomly-selected Australian adults aged 18 ± 78 y resident in the city of Adelaide, South Australia. MEASUREMENTS: Data on self-reported and measured height and weight as well as measured waist circumference were drawn from the Pilot Survey of the Fitness of Australians database. The proportion of men and women with acceptable BMI (BMI 25 kgam 2 ) and with excess abdominal adiposity ( ! 94 cm for men and ! 80 cm for women) was determined. Differences in the prevalence of overweight based on BMI alone or BMI and waist circumference were also determined. RESULTS: Compared with the prevalence based on self-reported BMI alone, the prevalence of overweight among men based on self-reported BMI and waist circumference combined was 2.4%, 5.3%, 19.1% and 7.5% greater for men aged 18 ± 39 y, 40 ± 59 y, 60 ± 78 y and for all men, respectively. Among women, compared with the prevalence based on selfreported BMI alone, the prevalence of overweight based on the combined measures was 9.9%, 24.0%, 33.3% and 20.6% greater for women aged 18 ± 39 y, 40 ± 59 y, 60 ± 78 y and for all women, respectively. CONCLUSIONS: If waist circumference is used as the criterion, then the prevalence of overweight among Australian adults, and probably other Caucasian populations, may be signi®cantly greater than indicated by surveys relying on self-reported height and weight. The development of valid self-reported measures of waist circumference for use in population surveys may allow more accurate epidemiological monitoring of overweight and obesity.

Physical inactivity contributes to premature mortality and morbidity and increasing prevalences of overweight and obesity in industrialized countries. Computer use is an increasingly common sedentary behaviour, potentially displacing physical activity. Physical activity and computer use were examined in 697 young adults (18-30 years). Energy expenditure estimates were derived from self-reported walking, moderate, and vigorous activity; participants were classified as sedentary, low, moderate, or high in their level of activity. For multivariate analyses, two categories of physical activity were used: inactive (sedentary/low activity; < 800 kcal.week-1) or active (moderate/high activity; > or = 800 kcal.week-1). Time spent in computer-related activities was summed, and computer use tertiles calculated (< 3 hours.week-1; 3-8 hours.week-1; > 8 hours.week-1). Those in the highest tertile of computer use were most likely to be inactive (p = 0.003) and most likely to report computer use as a barrier to physical activity (p < 0.001). The majority of those in the top two tertiles of computer use, and of the inactive, preferred obtaining information from computers than from conventional print media. These findings suggest that computer use plays a significant role in the discretionary time of young adults and is negatively associated with physical activity. Computer-mediated communication has potential in disseminating interventions to increase physical activity in young adults.

The aim of this study was to develop suitable spirometric prediction equations for asymptomatic Caucasian adults in the Australian population. These equations were compared with those of previous studies and constants were presented which, when associated with the prediction equations, permitted the calculation of 5% tolerance intervals for lung function. The 1,302 subjects (aged 18-78 yrs) who underwent pneumotachograph spirometry, using techniques recommended by the American Thoracic Society, were a sample from metropolitan Adelaide, South Australia. The variables recorded were sex, age, height, mass, forced expiratory volume in one second (FEV1), forced vital capacity (FVC), peak expiratory flow rate (PEFR), forced mid-expiratory flow (FEF25-75%) and FEV1/FVC ratio. Complete data were obtained for 614 females and 621 males, but the sample was reduced to 249 females and 165 males when only lifetime nonsmokers with no adverse bronchial symptoms were selected. Prediction equations of normal lung function were obtained from the reduced sample by multiple regression, with age, height and functions of both age and height as predictors. The derived equations did not differ significantly from the majority of previously reported equations and were generally superior in their ability to predict the lung function of the asymptomatic ex-smokers who were part of the original sample. Analysis of the sensitivity, specificity and predictive power of 5% tolerance limits for the presence of symptoms revealed the important roles of FEV1, FEV1/FVC and FEF25-75% in diagnostic testing. The present prediction equations are recommended for use on the Australian population and on populations with similar Caucasian characteristics.