Rate of Perceived Exertion and Cardiorespiratory Fitness in Older Adults with and without Alzheimer's Disease.

Exercise has many benefits for physical and cognitive health in older adults, yet there are many barriers to exercise adherence in this population. Subjective perception of exercise difficulty, or rate of perceived exertion (RPE), may especially be a barrier to exercise in individuals with Alzheimer's disease (AD), due to changes in initiation and motivation that accompany changes in cognition and brain function. RPE is the most commonly used measure of subjective effort in exercise research, yet the relationship between RPE and objective fitness is not fully understood in older adults. A better understanding is needed to support initiation, engagement, and maintenance of exercise and determine the appropriateness for use of RPE as a measure in this population. Our study aimed to 1) evaluate the degree to which objective measures of cardiorespiratory fitness correlates with the most commonly used subjective measure of effort, RPE and 2) examine any difference in the relationship between objective cardiorespiratory fitness and RPE between individuals with and without AD. We explored these relationships during a graded exercise test. Objective fitness and subjective effort were negatively associated. Independent of cardiorespiratory fitness, older age, female gender, cognitive impairment, and use of heart medications predicted greater self-reported effort during exercise. Results are discussed in terms of social psychological phenomena and potential neuropsychological deficits leading to increased subjective feelings of effort. These findings establish that the RPE measure may not be appropriate and may even detract from effort during graded exercise testing among older adults with AD.