The effects of green tea and exercise on cardiovascular health

INTERVENTION: The project will be investigating the effect of green tea capsules (GTC) acutely (one off ingestion of GTC) and chronically (8 weeks ingestion of GTC) on vascular health. Also the ingestion of GTC and its interaction with moderate intensity of exercise will be examined. A double blinded cross over design will be used in the study. Both acute and chronic settings will consist of two different interventional arms; ingestion of GTC (arm 1) and GTC plus exercise (arm 2). In the acute and chronic settings, the dose of GTC will be 1500 mg of GTC containing 375 mg of epigallocatechin gallate (EGCG), which will be taken orally in the morning. The exercise intensity for both settings will be at 65% of maximal oxygen uptake (VO2max) for 30 minutes. Thus, in the acute setting, cardiovascular function will be assessed following ingestion of one GTC (arm 1) then a week later (following a one week of wash out period) participants will perform exercise on a bike following ingestion of GTC (arm 2). In a chronic setting, participants will be provided GTC for the duration of 8 weeks. The GTC (1500 mg of GTC containing 375 mg of EGCG) will be taken orally once in the morning for 8 weeks (arm 1). Cardiovascular function then will be assessed at pre, 4 weeks, and 8 weeks post ingestion of GTC. Following one week of wash out, participants will ingest GTC every morning plus perform one‐on‐one sessions of supervised moderate intensity exercise at 65% of VO2max for 30 minutes, 3 times/week for 8 weeks (arm 2). Cardiovascular function then will be assessed at pre, 4 weeks, and 8 weeks post GTC plus exercise. CONDITION: Cardiovascular disease Overweight and obesity PRIMARY OUTCOME: Vascular function (e.g., forearm blood flow) will be assessed using Hokanson plethysmograph. Arterial stiffness will be assessed using SphymoCor. Whereas heart rate will be monitored through electrocardiograph (ECG). Blood pressure will be assessed using a beat‐by beat blood pressure monitor. SECONDARY OUTCOME: The metabolic response will be assessed through blood chemicals, such as assessment of insulin using Enzyme‐Linked Immunosorbent Assay (ELISA) kit and blood lipid profiles (using Cholestech). Whereas the autonomic responses (heart rate and blood pressure using ECG and blood pressure monitor) will be assessed while the mental challenge task (word conflict task/Stroop task) is administered to the participants. INCLUSION CRITERIA: The criteria for study entry is a body mass index (BMI) between 25‐35 kg/m2 and not to be involved in regular exercise (eg., exercise 4‐5 times per week at hard intensity for more than 4 years).