To evaluate the effects of Tai Chi-a mind-body exercise--on age-related loss of physiological complexity (using fractal and entropy based measures), and to understand the relationship between complexity, function and adaptability, we will conduct a two-arm prospective randomized clinical trial. Our overarching goal is to evaluate if six months of Tai Chi training, compared to a waitlist control receiving standard medical care, can enhance physiological complexity and adaptability in older Tai Chi-naïve adults. Secondary goals of the study are to characterize the relationship between complexity biomarkers, measures of function, and resilience. This pilot study will inform a future more definitive trial by providing information on recruitment and retention, compliance, dose-dependent effects, preliminary estimates of effect size, and the optimal biomarkers of complexity, function, and adaptive capacity.

Specific Aim #1: To determine if 6 months of Tai Chi training can increase complexity, function, and adaptive capacity of multiple physiological systems in older healthy adults. Specific Aim #2: To determine the relationships between biomarkers of physiological complexity, conventional measures of function and adaptive capacity. Statistical regression models will be used to determine relationships, both at baseline and overtime, between a) complexity biomarkers and measures of physical and cognitive function, and b) complexity biomarkers and adaptive capacity. Elucidating these relationships will further inform the interpretation of complexity biomarkers and provide insights into underlying component mechanisms contributing to complex physiological dynamics.

Inclusion Criteria:

• Ages 50-79
• Living within the Greater Boston area
• Willing to adhere to 6 month Tai Chi training protocol

Exclusion Criteria:

• Chronic medical conditions, including: cardiovascular disease (myocardial infarction, angina, atrial fibrillation, or presence of a pacemaker), stroke, respiratory disease requiring daily use of an inhaler, diabetes mellitus, malignancies, neurological conditions (e.g., seizure disorder, Parkinson's, peripheral neuropathy), or other neuromuscular or musculoskeletal (requiring chronic use of pain medication) disease
• Acute medical condition requiring hospitalization within the past 6 months
• Self-reported (current) smoking or alcohol/drug abuse
• Uncontrolled Hypertension (resting SBP > 160 or DBP > 100mm Hg)
• Abnormal heart rate (resting HR > 100 bpm; <50bpm)
• Abnormal ECG (supraventricular tachyarrhythmia, atrial fibrillation, significant ST wave abnormality, 2nd and 3rd degree heart block)
• Pregnancy
• Current use of prescription medications including cardio- or vaso-active drugs and medications that can affect autonomic function including Beta agonists and antagonists, drugs with anticholinergic properties (e.g. tricyclic antidepressants or anti psychotics), and cholinesterase inhibitor
• Self-reported inability to walk continuously for 15 minutes unassisted
• Regular Tai Chi practice within past 5 years
• Regular participation in physical exercise on average 4 or more times per week