A variety of studies has a need to estimate the amount and pattern of daily energy expenditure. To this end, a 3-day activity record was developed and is described. Every 15-min period over 3 days, including a weekend day, was qualified in terms of energy cost on a 1 to 9 scale corresponding to a range of 1.0 MET to 7.8 METs and higher. A reliability study of 61 subjects indicated a highly reproducible procedure as shown by an intraclass correlation of 0.96 for mean kcal of energy expenditure over 3 days. Repeatability was unchanged whether or not the hours of sleep were included in the record. Samples of 150 children and 150 adults were also drawn to investigate the relationship between energy expenditure, physical working capacity, and body fatness. Results support the hypothesis that mean energy expenditure per kg of body weight is significantly correlated with physical working capacity expressed per kg of body weight (r = 0.31; p less than 0.01). Mean energy expenditure per kg of body weight is negatively related to body fat (-0.08 less than or equal to r less than or equal to -0.13). It is concluded that the 3-day activity record is a procedure suitable to estimate energy expenditure in population studies.

In order to quantify genetic and environmental determinants of physical activity level, 1,610 subjects from 375 families who lived in the greater Québec city area completed a three-day activity record in 1978-1981. Level of habitual physical activity, which includes all the usual activities of life, and exercise participation, which includes activities requiring at least five times the resting oxygen consumption and more, were derived from this record. Familial correlations were computed in several pairs of biologic relatives and relatives by adoption after adjustment for the effects of age, sex, physical fitness, body mass index, and socioeconomic status, and analyzed with a model of path analysis that allows the separation of the transmissible effect between generations (t2) into genetic (h2) and cultural (b2) components of inheritance. The transmission was found to be statistically significant, but was accounted for by genetic factors for level of habitual physical activity (t2 = h2 = 29%), and by cultural factors for exercise participation (t2 = b2 = 12%). Although non-transmissible environmental factors remain the major determinants of these two physical activity indicators in this population, the results suggest that children can acquire from their parents certain customs regarding exercise behavior and that the propensity toward being spontaneously active could be partly influenced by the genotype.

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These results show that changes in the consumption of some specific food groups are associated with body-weight changes. Such specific eating patterns could help to improve obesity treatment and prevention.