September 17, 2018

Myles W. O’Brien1, Susan A. Robinson1, Ryan J. Frayne1, Said Mekary2, Jonathon R. Fowles2, Derek S. Kimmerly1

1 Division of Kinesiology, School of Health and High Performance, Faculty of Health, Dalhousie University, Halifax, Nova Scotia, Canada
2 School of Kinesiology, Acadia University, Wolfville, Nova Scotia, Canada

The Canadian Society for Exercise Physiology (CSEP) recommends that older adults (≥65 years) accumulate 150 minutes of moderate- to vigorous-intensity aerobic physical activity per week. Unfortunately, only ~12% of older adults in Canada achieve this recommendation and most spend ~70-80% of their waking hours engaged in sedentary behaviours like sitting. Combined, this contributes to an elevated risk of developing heart and blood vessels diseases. An early marker associated with many blood vessel diseases is poor function of the inner cell lining called the endothelium. The endothelium produces a chemical called nitric oxide, which relaxes blood vessels and makes them bigger. Although we know that aerobic exercise training can improve vascular health in older adults, the relationship between habitual physical activity and sedentary behaviours on endothelial function are less clear. This is especially true in the lower limb blood vessels of older adults which are most likely to develop disease.

The paper entitled, “Achieving Canadian Physical Activity Guidelines is Associated with Better Vascular Function Independent of Aerobic Fitness and Sedentary Time in Older Adults” by O’Brien et al. (2018) attempted to uncover the relationships between aerobic fitness levels, sedentary activity, and physical activity patterns on endothelial blood vessel health in both upper- and lower-limb arteries. Endothelial function was assessed using high-resolution ultrasound imaging during a flow-mediated dilation test. Briefly, this test involves 5-minutes of distal blood flow stoppage followed by another 5-minute period when blood flow is restored. When the blood flow stoppage is removed, a very large increase in blood flow occurs through the artery being imaged that results in an elevated production of nitric oxide from the endothelium causing the artery to get bigger. The larger it gets indicates a healthier endothelium. Aerobic fitness (VO2peak) was determined using a graded, maximal cycle ergometry test via indirect calorimetry. Activity monitors were used to determine weekly time spent engaged in moderate- to vigorous-intensity physical activity (i.e., PiezoRx®) or sedentary behaviours (i.e., activPAL®). Older adults were then divided into those who did, versus did not, meet the CSEP Physical Activity Guidelines.

The main findings by O’Brien et al. (2018) were that older adults who achieved the CSEP Physical Activity Guidelines had larger increases in artery size in response to the flow-mediated dilation test in both the upper- and lower-limb arteries than those who did not achieve these recommendations. Somewhat surprisingly, these beneficial blood vessel responses occurred despite the two groups having similar levels of aerobic fitness and time spent engaged in sedentary behaviours. Furthermore, when considering both groups together, there was a strong association between weekly moderate- to vigorous aerobic physical activity and lower-limb endothelial health. These findings highlight the need for population-focused interventions aimed at increasing the number of older adults who achieve the CSEP Physical Activity Guidelines to promote healthy aging and reduce their risk of cardiovascular diseases.

Original Article:

Myles O’Brien, Susan Robinson, Ryan Frayne, Said Mekary, Jonathon Fowles and Derek Kimmerly. Achieving Canadian physical activity guidelines is associated with better vascular function independent of aerobic fitness and sedentary time in older adults. Appl Physiol Nutr Metab. 2018 April 19.

This article is a summary of an article published in Applied Physiology, Nutrition & Metabolism. If you intend to cite any information in this article, please consult the original article and cite that source. This summary was written for the Canadian Society for Exercise Physiology and it has been reviewed by the CSEP Knowledge Translation Committee.