Can 2 Weeks of High Intensity Interval Training in Healthy 65-85 Year-olds Improve Cardiorespiratory Fitness?

Overview

The incidence of conditions requiring surgical intervention increases with age, however there is a reported decline in the rates of elective surgical procedures in those over 65. This is associated with older patients being described as "less fit" and more at risk of postoperative complications, leading to decreased provision of surgical care to those at need. Exercise interventions have the potential to reverse some of the decline in cardiovascular fitness associated with aging and improve the elderly's' "fitness for surgery" and potentially allow increased access to surgical care for those most in need of it.

The percentage of people aged \>65 y in the United Kingdom increased from 15% in 1985 to 17% in 2010, an increase of 1.7 million people. One age-associated physiological change is the reduction in vascular function that is observed, both at the levels of the large arteries and the muscle microvasculature. In itself this vascular dysfunction is associated with reduced aerobic performance. Cardiorespiratory fitness (marked by aerobic performance) has been shown to be an independent predictor of postoperative mortality, which provides more accurate prognostic information than age alone. In contrast, physical activity can reverse elements of pathophysiology associated with these conditions, including vascular dysfunction. Nonetheless, major roadblocks to exercise as a strategy to combat age-associated vascular dysfunction and associated conditions exist, such as poor exercise tolerance and "lack of time". The aim of this study is to investigate whether if novel low-volume, time-efficient training strategies can improve indices of vascular health and cardiorespiratory performance in older individuals with a view towards improving their fitness for surgery. Numerous studies have demonstrated that periods of supervised exercise training effectively improve indices of cardiorespiratory (blood pressure, aerobic capacity and blood lipids and vascular function. However, the majority of these studies were conducted using high-volume continuous submaximal aerobic training (e.g. 50-65% VO2max for 30-60 min) or moderate to high volume progressive weight training. This research group have recently shown the efficacy of a time-efficient exercise strategy known as HIIT - High Intensity Interval Training, for improving VO2 max and muscle mass in young individuals with heightened metabolic disease risk and also demonstrated significant improvements in VO2 max comparable to classic aerobic exercise training using several different time-efficient HIIT protocols in as little as 4 weeks. This study aims to quantify the benefits of 2 weeks of HIIT.