Effects of Exercise Intervention on Aging-related Motor Decline
Condition: Aging; Exercise
Study type: Interventional

Summary: 
      The purpose of this research study is to test whether differing levels of physical fitness
      affects patterns of motor dexterity and brain activity that have been shown to differ due to
      aging. Testing will take place at the Atlanta VA Medical Center and at Emory University.

      Participants will be healthy adults within the target age range of 60-85 for the study. The
      study will require multiple visits over 15 months. There will be about 64 people volunteering
      for this study.
    

Detailed description: 
      The U.S. Census reports over 14 million U.S. Veterans (>63%) are beyond mid-life (>55 years).
      Declines in upper extremity motor performance respective of strength and dexterity are well
      documented within this age cohort). Recent cross-sectional research has discovered that aging
      related motor deficits may be influenced by a loss of interhemispheric inhibition (IHI)
      between primary motor cortices. However, this loss may not be an inevitable consequence of
      aging. Work from previous VA OAA Predoctoral and CDA-1 awards have shown that aerobic fitness
      may serve to mitigate losses in interhemispheric inhibition assessed by both functional
      magnetic resonance imaging (fMRI) and transcranial magnetic stimulation (TMS). That is,
      individuals who are aerobically fit show higher levels of IHI and improved dexterity and
      reaction times.

      In light of new evidence from the investigators' lab's recent cross-sectional studies,
      physical activity over the long term (at least 2-5 years) may serve to alter levels of IHI
      and improve motor performance in the upper extremity. Aerobic exercise may provide a
      mechanism (reduced loss of interhemispheric inhibition) that could serve to improve motor
      function, but the neural mechanism responsible for such effects remains unclear. Previous
      investigations of interhemispheric communication and exercise have been limited by nature of
      inquiry, as cross-sectional research cannot measure changes over time in participants. As
      such, it is currently unknown how exercise may directly affect levels of interhemispheric
      communication and motor performance.

      Behavioral interventions (motor strength and coordination) have been shown to be effective in
      improving upper extremity motor performance in older adults, however the duration of these
      gains appear to be short-lived. After as little as a few weeks of detraining, motor strength
      and coordination in the upper extremity rapidly begins to return to pre-intervention levels.
      Evidence from exercise interventions assessing gait and locomotion have shown that exercise
      programs over a longer term (>6 months) are associated with improved proprioception, fewer
      falls and better balance. However, the comparison of outcomes of upper extremity function in
      elderly adults respective of exercise duration remains largely unexplored. In addition to
      comparing the effects of short-term exercise (3 months) versus behavioral training (3 months)
      on upper extremity function, the current proposal will evaluate if a longer-term (6 months)
      exercise program can maintain or enhance upper extremity function and associated levels of
      interhemispheric inhibition.

      The current study proposes the next logical step in my line of research and directly
      investigates the effects of exercise in an intervention with sedentary older Veterans (50-80
      years), a group most likely to exhibit aging-related motor deficits. The investigators
      propose to enroll 40 Veterans into an upper extremity dexterity improvement program involving
      behavioral and exercise components. The behavioral intervention is a muscle coordination
      training previously shown to improve unimanual motor performance in older adults. The
      exercise intervention is a supervised group cycling regimen. The figure below shows the study
      design. Interhemispheric communication will be assessed with fMRI, and TMS.
    

Intervention name(s): Stretching Exercise Intervention; Aerobic Exercise Intervention; Self Monitoring
Intervention type(s): Behavioral; Behavioral; Behavioral
Intervention description(s): A. Light stretching and balance exercises under supervised trainer. 3 times per week for 20-45 minutes. HR will be targeted to be under 50% of age-related maximum.; Supervised weekly exercise. 3 bouts of 45 minutes weekly on a cycle ergometer. HR will be kept at 75% of age-related maximum.; 6 month self-monitored training phase during which time participants will exercise according to prescribed regimen (cycling)
Allocation: Randomized
Intervention model: Crossover Assignment
Intervention model description: A. Light stretching and balance exercises under supervised trainer. 3 times per week for 20-45 minutes. HR will be targeted to be under 50% of age-related maximum.
B. Interval aerobic cycling under supervised trainer. 3 times per week for 20-45 minutes. HR will be targeted between 50-85% of age-related maximum.
C. 6 month self-monitored training phase during which time participants will exercise using a take home bike ergometer
Masking: None (Open Label)
Primary purpose: Basic Science
Keywords: Exercise; Magnetic Resonance Imaging; Transcranial Magnetic Stimulation; Aging