Dose Response Study of Aerobic Exercise in Older Adults
This 26-week study will assess the effects of three doses of moderate-intensity exercise in sedentary older adults who have age-related cognitive changes but no dementia. Aerobic fitness, physical function, and cognition will be assessed at baseline and 26 weeks to examine the dose-response relationships. At 52 weeks, cognition will be reassessed to examine the durability of cognitive changes.
Underactive or sedentary, based on the Telephone Assessment of Physical Activity
Community dwelling, with a caregiver willing to accompany the participant to clinic visits; caregiver must visit with the subject more than five times a week
Nondemented: Clinical Dementia Rating = 0
Adequate seeing and hearing abilities to perform all aspects of the cognitive and functional assessments
Stable doses of medications for at least 30 days prior to screening are allowed
Dementia: Clinical Dementia Rating > 0
Current major psychiatric disorder; significant psychiatric symptoms (e.g., hallucinations) that could impair completion of the study
Current clinically significant systemic illness or infection likely to result in deterioration of the participant's condition or safety during the study
History of clinically evident stroke; myocardial infarction or symptoms of coronary artery disease (e.g., angina) in the last 2 years; uncontrolled hypertension within the last 6 months
History of cancer within the last 5 years (except nonmetastatic basal or squamous cell carcinoma)
History of drug or alcohol abuse
Insulin-dependent diabetes mellitus
Significant pain or musculoskeletal disorder that would prohibit participation in an exercise program
This study will assess the effects of three doses of moderate-intensity exercise in sedentary older adults who have age-related cognitive changes but no dementia. Participants will be randomized to a control group or groups that perform 75 minutes, 150 minutes, or 225 minutes per week of aerobic exercise, spread over 3 to 5 days a week for 26 weeks. These exercise doses represent 50 percent, 100 percent, or 150 percent of the federally recommended exercise dose.
Participants will be directly supervised during all exercise sessions for the first 2 months, after which direct supervision will occur during at least one session a week. Aerobic fitness, physical function, and cognition will be assessed at baseline and 26 weeks to examine the dose-response relationships. At 52 weeks, cognition will be reassessed to examine the durability of cognitive changes.