The modulatory effects of sedentary behaviour and physical activity on older adults' cardiovascular/metabolic profiles

• Main Author: Ryan, Declan John
• Published: Manchester Metropolitan University 2018
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.765179

Cardiovascular disease (CVD) is the greatest cause of mortality, after cancer, in older adults (>60 years). CVD risk can be modulated by sedentary behaviour (SB) and physical activity (PA) however, research examining the effect of SB and PA on older adults' cardiovascular/metabolic profile is lacking. This thesis aimed to address this gap in the literature. Ninety-three independently living older adults wore a thigh-mounted triaxial accelerometer for 7 consecutive days to assess habitual SB and PA engagement and patterns. Fasting blood samples to assess seven cardiometabolic marker concentrations and ultrasound to assess vascular structure and function were conducted. Engagement in light intensity PA (LIPA) decreased popliteal intima-media thickness (IMT) and further ageing of popliteal IMT. Replacing one hour of SB with LIPA decreased carotid artery diameter. Replacing an hour of any SB or PA with moderate to vigorous PA (MVPA, ≥10 mins bouts) reduced triglyceride concentration. Those with a 'low' triglyceride and 'high' lipoprotein lipase concentration engaged in 48% and 11% more MVPA (≥10 mins bouts) than the entire sample population, respectively. Patterns of SB, specifically W50% was associated with an increase in popliteal IMT and resting heart rate. Furthermore, participants with a 'high' procollagen 3 N-terminal peptide concentration had a larger W50% than the 'low' group. For SB, patterns of engagement appeared to be better predictors of older adults' cardiovascular/metabolic status than total engagement time. LIPA is suggested to be a useful replacer of SB time due to their high co-dependence. MVPA (≥10 min bouts) engagement, which is already recommended in government PA policies, was a strong mediator of cardiometabolic markers. Overall, this thesis suggested that government PA policies should also include objective recommendations for SB and LIPA, as the entire intensity spectrum of SB and PA affected older adults' cardiovascular/metabolic profile.