Comparison of estimates of population levels of physical activity using two measures.
OBJECTIVE
To compare estimates of population levels of 'adequate activity' for health benefit in different age and sex groups using two different measures--kilocalories (kcals) and Mets.mins.


METHODS
10,464 mid-age women (47-52 years) from the second survey of the Australian Longitudinal Study on Women's Health (ALSWH, 1998) and 2,500 men and women (18-75 years) from the 1997 Active Australia national survey, answered questions about physical activity. Kcals and Mets.mins were calculated from self-reported time spent in walking, moderate and vigorous activity, and self-reported body weight. 'Adequate activity' was defined as a minimum of 800 kcals or 600 Mets.mins.


RESULTS
There were differences in the estimates of 'adequate activity' using the two methods among women participants in both surveys, but not among the male participants in the Active Australia survey. A significant proportion of the women in both surveys (6.4% of the ALSWH women and 8.5% of the Active Australia women, mean weight 60 kg) were classified as 'inactive' when the kcals method was used despite reporting levels of activity commensurate with good health. Fewer than 1% (mean weight 105 kg) were classified as 'active' using kcals when reporting lower than recommended levels of activity. Agreement between the two methods was better among men; only 3% were misclassified because of low or very high weight.


CONCLUSIONS
The Mets.mins method of estimating 'adequate' activity assesses physical activity independently of body weight and is recommended for use in future population surveys, as it is less likely to under-estimate the prevalence of physical activity in women.


CONCLUSIONS
Women and men aged 45-59 and women aged > 60 should be the target of specific health promotion strategies to increase population levels of physical activity.
Brown
W J
WJ
School of Human Movement Studies, University of Queensland. wbrown@hms.uq.edu.au
Bauman
A E
AE
D000293:Adolescent; D000328:Adult; D000368:Aged; D001315:Australia / Q000453:epidemiology; D003625:Data Collection; D015444:Exercise / Q000502:physiology*; D005260:Female; D015438:Health Behavior; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D016387:Women's Health