The relative contribution of sex, ethnicity, social class, parental exercise and heart health knowledge to the variability of sporting activities reported by Texas 7th and 8th grade students in 1980 was examined to study the cultural patterns of exercise that might relate to future risk for heart disease. Girls were more likely than boys to participate in activities with high aerobic potential. Relative to Mexican-Americans and Blacks, Anglos were more likely to engage in individual, non-competitive, aerobic-type activities. Multivariate analysis showed heart knowledge, parental exercise, sex, father's occupation and ethnicity to be significantly related to the overall frequency of exercise. Parental exercise had a stronger influence on the frequency of exercise among girls than boys. These findings suggest possible cultural mechanisms in the epidemiology of heart disease.