Endothelial function of the skeletal muscle vasculature declines with advancing age. Although aerobic exercise training is commonly prescribed to combat loss of endothelial function in the elderly, the rate of compliance to training programs is low. Contrary to aerobic exercise training, stretching exercise is widely performed in elderly patients to increase muscle flexibility and to prevent muscle atrophy induced by immobilization. However, it remains unknown as to whether regular stretching of the calf muscles using ankle dorsiflexion splinting improves muscle blood flow. The purpose of the proposed work is to test the hypothesis that performance of ankle dorsiflexion splinting improves endothelial function and lower leg muscle blood flow in older adults. Ankle dorsiflexion splinting will be performed on the randomized leg for 30 minutes, 5 times per week for 4 weeks. Leg vascular measures will be performed on the splinted and non-splinted legs prior to and at the end of the 4-week intervention.

Older adults will be recruited in this study. Vascular function will be assessed before and after the 4-week ankle splinting intervention. To examine the acute effects of splinting, vascular measures will also be obtained before and immediately following 30 min of ankle splinting. All procedures will be performed at the Integrative Cardiovascular Physiology Laboratory at the University of Florida.

Participants will have one leg randomly assigned to using a splint to stretch the calf muscles 30 min per day, 5 days per week for 4 weeks, while the contralateral non-splinted leg will serve as an internal control.

Inclusion Criteria:

• Men and women aged 60 to 79 years.
• Women will all be postmenopausal and must not take hormone replacement therapy.
• Sedentary, defined as no regular exercise training.

Exclusion Criteria:

• No evidence of heart disease evidenced by abnormal resting ECG, angina or ECG evidence of acute myocardial ischemia during the exercise test, no history of any relevant acute cardiac event (myocardial infarction, episode of heart failure)
• No history of deep vein thrombosis.
• No history of Type I or II diabetes mellitus.
• No history for renal or liver disease.
• No history of seizures, or other relevant on-going or recurrent illness.