Creatine Monohydrate Supplementation and Vascular Endothelial Health

To determine the effects of 4 weeks of creatine monohydrate supplementation on markers of macrovascular and microvascular function, cognitive performance, and physical performance.

This is a randomized, double-blind (participant and principle investigator), placebo-controlled, crossover study.

After a pre-screen telephone interview, potential participants will be invited to Florida State University for a "Screening visit". During this visit, individuals will be provided with a verbal and written explanation of the study. Individuals will complete an informed consent, a health history questionnaire and physical activity readiness questionnaire. If they meet study inclusion criteria, they will undergo anthropometric measurements and a venous blood draw to determine cardiovascular and kidney disease risk profile. If cleared for participation, participants will be asked to complete a "3-Day Food Log" prior to their next visit.

Once qualified, participants will return to the laboratory to undergo their "Baseline Testing Visit". Following the completion of the first "Baseline Testing Visit", participants will be randomly assigned to one of two interventions: 1) creatine monohydrate; or, 2) maltodextrin "placebo". Participants will be given their supplement and asked to complete the supplementation protocol, complying with instructions given. Following the 4-week supplementation period, participants will return to the laboratory for their "Post-Supplement #1 Testing". During this visit, all procedures from the "Baseline Testing Visit" will be repeated.

Once these measurements are completed, participants will be asked to return to their normal daily lifestyles for a 4-week "wash-out" period. During these 4-weeks, participants will be contacted weekly to ensure retention and to schedule the next visit. Following the washout, participants will return to the laboratory to undergo another "Baseline Testing Visit", completing the exact procedures as outlined previously. Following this, participants will be given their remaining supplement intervention. Following the intervention, participants will return to the lab for their final "Post-Supplement #2 Testing" to conclude the study.

Eligibility Criteria:
Inclusion Criteria:

* both male and female
* 50-64 years old
* no restrictions based on race, ethnicity, or socioeconomic status
* sedentary individuals (\<20 minutes; \<3 days/wk. physical activity)
* post-menopausal women (has experienced 12 consecutive months without menstruation for \>5 years).

Exclusion Criteria:

* \<50 or ≥65 years of age
* Subjects participating in regular exercise (\>20 min/day, \>3 days/week)
* female subjects who are pregnant, lactating or 1 month post-partum
* currently consuming or had consumed creatine supplementation \<1 month prior to screening
* currently consuming or consumed nitric oxide supplementation \<1 month prior to screening
* currently consuming or had consumed Vitamin C supplementation \<2 weeks prior to screening
* individuals who report chronic infections
* individuals reporting paralysis due to stroke
* individuals reporting advanced Parkinson's disease
* individuals reporting severe rheumatoid arthritis or other serious orthopedic problems that would prevent performance of the exercise tasks
* individuals currently taking medications that may affect central or peripheral circulation
* individuals with known cardiovascular and/or metabolic disease
* current smokers or those who quit \<6 months prior to screening
* individuals with hypercholesterolemia (total cholesterol \> 200mg/dL, high density lipoprotein \<40 mg/dL, low density lipoprotein \>130mg/dL)
* individuals with hypertension (systolic blood pressure \> 150 mmHg and/or diastolic blood pressure \>95mmHg).
* individuals with known kidney disease
* individuals with known liver disease