Improving brain health in at risk populations with aerobic exercise

Aerobic exercise The objective of this research is to investigate the effects of regular aerobic exercise on cerebrovascular function, mood and cognition in middle-aged to older adults. A randomised control trial that aims to determine whether a high or low level of aerobic exercise training for 16 weeks can improve cerebrovascular function, mood and cognition in a physically inactive, middle-aged to older, overweight and obese cohort who are at risk of cognitive decline and dementia. It is hypothesised that both the higher levels of exercise training will improve cognition and mood in this cohort by improving cerebrovascular function, as well as improving cardiovascular function and general physiological and psychological markers of health. However, it is unknown if less aerobic exercise training will elicit any changes in cognition and mood by improving cerebrovascular function. Hence, the aim here is to determine the optimal amount of aerobic exercise training to improve the aforementioned outcomes. We will aim to recruit one hundred and thirty-five participants for this study. Recruitment will occur via an approved media release that incorporates physical advertisement, social media and information on the USQ website. The individuals will be recruited from community organisations in and around Ipswich, Toowoomba and Brisbane. Respondents will initially be screened for suitability using the Exercise and Sports Science Australia (ESSA) Adult Pre-exercise Screening System, the Yale Physical Activity Survey and a medical history questionnaire to determine whether participants meet the inclusion and/or exclusion criteria. Once participants are recruited, voluntary written informed consent will be obtained prior to any assessment being performed and their allocation to one of the two arms of the study at a 2 is to 1 ratio (intervention:control). Further, participants will be asked to complete a nutritional questionnaire at 0 and 16 weeks, so that this can be assessed and that any effects that are noted throughout the study are due to the exercise intervention and not due to changes in nutritional behaviour. The two arms of this study will consist of a wait-list (control group), which will not participate in any exercise training, and a second arm (the exercise group) that will participate in 2 – 4 aerobic exercise sessions per week. Participants that are allocated to the exercise arm will participate in aerobic exercise training for either two, three or four days per week for 16 weeks (i.e., the participant can choose how many sessions they attend). These sessions will be conducted as supervised group sessions run by student exercise physiologists in the presence of an accredited Clinical Exercise Physiologist at the University of Southern Queensland Ipswich Campus. Participants in the second arm or exercise arm of the study can attend any of these sessions, as long as they participate in a minimum of two sessions per week. All sessions will last for 40 min, incorporating both a 5-min gentle warm-up and cool-down. The body of the sessions will be performed at a moderate intensity (Borg RPE 5-6), vigorous-high intensity (Borg RPE 7-8) or a mix of the two. Participants will be requested to perform these exercise sessions at a higher intensity every four weeks from the previous four weeks (this will be based on the Borg rating of perceived exertion (CR-10) scale). These sessions will incorporate steady-state aerobic exercise (i.e. walking), circuit training or a mix of the two types of training. Once informed about the study and its requirements, by providing potential participants with a participant information sheet, participants that meet part of the inclusion criteria will attend USQ Ipswich for baseline screening and testing. Prior to the start of any testing during visit 1, informed consent will be first voluntarily obtained and, once acknowledged, testing and screening will commence. These visits will incorporate the following methods: • Cerebrovascular responsiveness to hypercapnia and cognitive stimuli (NIH Toolbox, Trail Making Task) using transcranial Doppler sonography; • Profile of Mood States to ascertain current mood; • Anthropometry, determined by body weight and height (body mass index calculation), waist and hip circumferences (waist to hip ratio calculation) and Dual-energy X-ray absorptiometry (DEXA) which will ascertain body composition of total fat mass, lean mass, body fat percentage, and bone mineral content and density; • Systolic and diastolic blood pressure and arterial elasticity will be measured non-invasively using a Research Cardiovascular Profiling System; • Biomarker analyses after blood is collected; and • Exercise capacity will be assessed using a 6 minute walk test at 0 and 16 weeks and handgrip strength will be determined using hand dynamometry.