Physical Activity, Aging, Waist Circumference, and Medication Use in Relation to Metabolic Health and Mortality Risk

Research that investigates effective assessment or treatment of conditions associated with physical inactivity and obesity is warranted, as these factors pose a large public health challenge. The first study in this thesis demonstrated that participating in physical activity (PA) even once a week was associated with lower all-cause mortality risk compared to no PA (P<0.05). However, only in very old adults was participating in PA more than once per week associated with an even lower mortality risk (P<0.05). The second and third studies determined that adults with type 2 diabetes (T2D) or hypertension who were physically active, treated and controlled had a significantly lower mortality risk as those who were physically inactive, regardless of treatment or control (P<0.05), a similar mortality risk as adults without T2D (P>0.05), and a higher mortality risk compared to physically active adults without hypertension (P<0.05). These studies demonstrate the importance of a higher frequency of PA in very old adults, and the benefits of PA on mortality risk in adults with hypertension or T2D.
The fourth study demonstrated that adults with overweight and not attempting weight loss had the greatest error in estimating vigorous energy expenditure, and calories in food. However, among all participants, there was a large individual error in calorie estimation. The overall poor understanding of energy expended through exercise and calories in food may have important implications for weight management. The fifth study determined that adults consider the clinically recommended waist circumference (WC) measurement sites (iliac crest and midpoint) the most difficult sites to self-measure (P<0.05). However, there were no differences in the accuracy of self-measurement, or the association between WC and blood pressure between measurement sites, but there were large variations in the prevalence of abdominal obesity between sites (0-18% for normal weight; 21-78% for overweight). Therefore, there may be no clear advantages of measuring one WC site over another. In summary, even modest amounts of PA are effective for reducing mortality risk, and may be particularly beneficial in very old adults, and among adults with T2D or hypertension. In addition, effective methods for long term weight management are needed.