Weather and Sex-Specific Daily Step Counts in Japanese Adults: A Quadratic Analysis

Background: Our study examined the sex differences in the relationship between meteorological conditions and objectively measured daily step counts among Japanese individuals living in the community. Objectives: In this study, we explored the correlations between meteorological conditions [including maximum, minimum, and mean temperatures, and the Temperature-Humidity Index (THI)] and objectively measured daily step counts. Methods: The data collected throughout the year included a sample of 2,076 sedentary individuals in good health (631 men and 1,445 women). Furthermore, we collected additional information such as the healthy lifestyle scores of the participants and medication data. Using receiver operating characteristic (ROC) curve analyses, we identified the weather conditions that correlated with optimal daily step counts and stratified them with respect to the sex of the participants. Results: The mean daily step count values for men and women were 9,516 and 7,450 steps, respectively. For men, the identified cut-off values [area under the curve (AUC)] of various weather parameters for achieving 10,000 daily step counts were as follows: Maximum temperature of 17.4°C (0.732), mean temperature of 15.7°C (0.713), minimum temperature of 12.4°C (0.691), THI of 59.7 (0.711), and a maximum THI of 63.1 (0.724). In contrast, for women, the corresponding cut-off values (AUC) of various weather parameters for achieving 8,000 daily step counts were as follows: Maximum temperature of 20.2°C (0.645), mean temperature of 15.7°C (0.630), minimum temperature of 12.6°C (0.613), THI of 59.7 (0.626), and a maximum THI of 66.1 (0.637). Conclusions: Our findings demonstrated the impact of meteorological data, including maximum temperature and THI, on the daily step count. Such information is deemed invaluable in providing exercise guidance to mitigate the risk of lifestyle-related diseases, such as diabetes.