Associations of Physical Activity Behaviors and Cardiovascular Fitness with Carotid Atherosclerosis: Cooper Center Longitudinal Study
Presence of carotid atherosclerosis is an important risk factor for stroke events. In the 2008 Physical Activity Guidelines for Americans, it was concluded that there is strong evidence to support that physical activity and cardiorespiratory fitness (CRF) reduces risk of stroke in adults. However, very few studies examining the association between physical activity or CRF and carotid atherosclerosis have been conducted to date. Of these limited studies, most have examined these associations in midlife populations, although cardiovascular diseases (CVD), including ischemic stroke event, are more common later in life. Therefore, the overall objective of this dissertation study was to examine the associations of physical activity behaviors, including aerobic physical activity, muscle strengthening activities (MSA), and CRF with risk of carotid atherosclerosis in a well-characterized sample of older adults aged 65 years and older. ^ This study was a secondary data analysis of data from the Cooper Center Longitudinal Study (CCLS) from 1970 to 2017. CCLS is an ongoing prospective cohort study established in 1970 in Dallas, TX, USA that aims primarily to understand the effect of lifestyle behaviors on morbidity and mortality risk. In addition, beginning in 2011, a carotid ultrasound scan was included as an optional component to the preventive medical examination and offered to participants aged ≥ 65 years. Aerobic physical activity and MSA were measured by medical history questionnaire and expressed both continuously and categorically based on 2008 Physical Activity Guidelines for Americans. CRF was estimated objectively with a maximal treadmill test and expressed categorically (high, moderate, and low) based on the quintiles of maximal time on the treadmill. Comon carotid artery (CCA) intima media thickness (IMT), plaque and stenosis condition on the CCA, carotid bulb, internal carotid artery (ICA), and external carotid artery (ECA) were measured by carotid ultrasound scan. ^ Findings from Paper 1 and 2 supported the null association shown in previous studies between aerobic physical activity or MSA and carotid atherosclerosis measures in an older adult sample. In addition, findings from Paper 3 demonstrated an independent, inverse association between midlife CRF and carotid IMT within the first 300 months of follow-up. Further, midlife BMI was also independently associated with carotid IMT in later life. Finally, when compared to those with low CRF and obesity in midlife (reference group), participants with low CRF and normal BMI, moderate CRF and overweight, high CRF and overweight or normal BMI had a 70.0%, 48.5%, 77.2%, and 64.3% reduction in risk of carotid IMT in older adulthood (all p<0.05). ^ The results of these analyses suggest that physical activity behaviors, including aerobic physical activity and MSA, in older adulthood are not related to markers of carotid atherosclerosis, assessed at the same point in time. However, based on the findings of Paper 3, behavior modification (e.g., habitual physical activity) to optimize CRF and BMI during midlife may have long lasting vascular benefits.^
Lee, Joowon, "Associations of Physical Activity Behaviors and Cardiovascular Fitness with Carotid Atherosclerosis: Cooper Center Longitudinal Study" (2017). Texas Medical Center Dissertations (via ProQuest). AAI10682254.