Background: Physical activity is thought to play an important role in the maintenance and promotion of health, and practical questionnaires assessing levels of physical activity are currently a widely used method in epidemiological research.
Methods: As a part of the Japan Collaborative Cohort Study (JACC Study) for Evaluation of Cancer Risk sponsored by the Ministry of Education, Science, Sports and Culture of Japan (Monbusho), we investigated the status of physical activity of cohort participants aged 40-79. A total of 110,792 participants (46,465 men and 64,327 women) completed the baseline survey from 1988-1990. Questionnaires concerning physical activity contained the following questions: 1) How much time per week on average do you spend engaging in sports or physical exercise? (at least 5 hours, 3-4 hours, 1-2 hours, little); 2) How much time per day on average do you spend walking either indoors or outdoors? (longer than 1 hour, 30 min-1 hour, about 30 min, little).
Results: In total, 68.7% of men and 76.2% of women responded with "little" to the amount of time spent engaged in sports or physical exercise. The proportion of time spent on habitual physical exercise (sports and physical exercise of one hour or more per week) was lowest in the 50-59 years age group and increased with age among participants aged 50-79. In addition, 49.4% of men and 50.7% of women responded with "more than 1 hour per day" to the amount of time spent walking.
Conclusion: These results show that the proportion of habitual physical exercise was relatively low in the JACC Study and increased with age among participants aged 50-79, whereas almost half walked for more than one hour a day.