Caffeine consumption appears to be associated with higher levels of physical activity in Japanese women. - GreenMedInfo Summary

Caffeine has been described as a sports performance-enhancing substance. However, it is unclear whether it can increase the level of physical activity in non-athletic individuals. This study investigates the relationship between daily caffeine consumption and (1) daily physical activity/fitness or (2) intervention-induced changes in physical activity in women and men. On the basis of responses to a dietary habit questionnaire, which included items on caffeinated beverages, 1032 Japanese adults, were categorized into lower- or higher-caffeine-consumption groups (relative to the median caffeine consumption). In each group, daily step-count, sedentary time, and light, moderate, and vigorous physical activity outcomes were objectively measured. Physical fitness, including peak oxygen consumption, was also evaluated. The relationship between daily caffeine consumption and the change in the levels of physical activity was investigated in a subgroup of 202 subjects who participated in a one-year physical activity counselling intervention. Women in the higher-caffeine-consumption group presented higher moderate-to-vigorous physical activity and step-count compared with their counterparts in the lower-consumption group (4.0±2.1 vs. 3.3±2.1 MET-h.day-1, p<0.001, 10335±3499 vs. 9375±3527 steps/day, p<0.001). A significant positive correlation was noted between caffeine consumption and peak oxygen consumption among women (r=0.15, p<0.001). No caffeine-related effects were noted in men. The lower- and higher-caffeine-consumption groups showed no significant differences in their levels of physical activity at the end of the one-year intervention. Caffeine consumption, therefore, appears to be associated with higher levels of physical activity in Japanese women. Further studies are needed to clarify this association.