Physical activity (PA) is an independent predictor of mortality and frailty in middle-aged women, but fatigue remains a major barrier in this group. While caffeine intake has been associated with reduced exertion and perceived fatigue, it is not well understood whether consumption of naturally caffeinated drinks is associated with physical activity. The aim of this study was to determine whether habitual consumption of coffee and tea is associated with participation in physical activity. Women (n = 7580) from the Australian Longitudinal Study on Women's Health were included in this investigation. Participants reported average tea and coffee intake over the last 12 months and usual PA. Logistic regression models were adjusted for relevant health and lifestyle confounders, and Sobel test was used for mediation analysis. Participants who consumed 1⁻2 cups of coffee/day were 17% more likely to meet the recommended 500 metabolic equivalent (MET).min/week than women who had <1 cup/day (odds ratio (OR) 1.17, 95% confidence interval (CI) 1.04⁻1.32). Participants who reported drinking either 1⁻2 cups or >3 cups/day of tea were 13⁻26% more likely to meet 500 MET.min/week than those who had <1 cup/day (OR 1.26, 95% CI 1.08⁻1.46 and OR 1.13, 95% CI 1.01⁻1.26, respectively). Tiredness and energy mediated associations between intake of coffee (fully) and tea (partially) and PA. Middle-aged women who drink 1⁻2 cups of coffee or >1 cup of tea/day are more likely to meet the moderate-to-vigorous PA guidelines than those who drink <1 cup/day. Future research is warranted to investigate causality and effects of specific coffee and tea amounts.
Keywords: caffeine; fatigue; mediation analysis; middle-age; physical activity.