Currently, university students face physical and mental health issues, which are reflected in low levels of physical activity, a decline in healthy eating behaviors, and a high prevalence of mental health symptoms such as stress, anxiety, and depression. Therefore, it is necessary to develop safe, effective, and sustainable interventions that support comprehensive health and provide formative experiences that reinforce the importance of developing healthy lifestyle habits and self-care.

In this regard, Tai Chi has been shown to offer physical and mental health benefits. Tai Chi is a low- to moderate-intensity exercise with low joint impact, which facilitates the transition from a sedentary to an active lifestyle.

Considering the health problems experienced by university students, it is proposed that a Tai Chi intervention could help produce beneficial effects on both physical and mental health. In this context, the present study aims to implement Tai Chi classes with the objective of determining their effect on the cardiac autonomic system, mental health, and the perception of benefits, facilitators, and barriers among participating university students compared to a control group.

In Chile, there are currently over 1.2 million undergraduate university students who exhibit low levels of physical activity and mental health issues such as anxiety and depression. These problems tend to worsen after the first year of higher education, along with the development of unhealthy eating habits and weight gain.

In this context, Tai Chi has shown multiple benefits for overall health. Specifically, the Sun style of Tai Chi is characterized by gentle and accessible movements, making it well-suited to the university setting, and has demonstrated positive effects on both physical and mental health.

Previous studies indicate that regular practice of Tai Chi may positively influence autonomic cardiac control, measured through heart rate variability (HRV), as well as mental health. However, the available evidence is still limited and heterogeneous.

This study aims to evaluate, in university students, the effects of a 6-week Sun Tai Chi program, with 60-minute sessions held twice per week, on the following:

• Heart Rate Variability (HRV), as a marker of cardiovascular health and stress,
• Mental health, assessed with the Depression Anxiety Stress Scales - 21 Items (DASS-21 scale),
• Participants' qualitative perceptions regarding the program's benefits, barriers, and facilitators.

Given the limited research on Tai Chi in university student populations, this study seeks to contribute evidence on its potential comprehensive health benefits in this group.

Inclusion Criteria:

• Undergraduate university students
• Aged 18 to 29 years
• Both sexes
• Present mental health symptoms assessed by the Depression Anxiety Stress Scales - 21 Items (DASS-21) questionnaire, according to cutoff points established by Lovibond et al., ranging from mild to severe in any of the subscales of stress (score 15 to 33), anxiety (score 8 to 19), or depression (score 10 to 27).
• Report a healthy physical condition suitable for Tai Chi practice (self-reported).

Exclusion Criteria:

• Engage in a high level of physical activity according to the International Physical Activity Questionnaire (IPAQ) or have regularly practiced moderate to high intensity physical activity in the last 3 months.
• Report chronic illnesses that limit or contraindicate the practice of exercises required in Tai Chi.
• Present cardiovascular, pulmonary, or neurological diseases.
• Exhibit either no mental health impairment or severe impairment according to cutoff scores established by Lovibond et al. in the DASS-21 questionnaire (stress subscale score lower than 15 or greater than 33, anxiety subscale score lower than 8 or greater than 19, depression subscale score lower than 10 or greater than 27).
• Present specific psychiatric diagnoses, such as Attention-Deficit/Hyperactivity Disorder (ADHD), self-reported.
• Consume medications for mental health treatment.
• Consume medications or substances that influence cardiac autonomic modulation (e.g., beta-blockers).