**Background:** Atherosclerotic cardiovascular diseases (ASCVDs) account for approximately 85% of global cardiovascular mortality. Older adults are at increased risk, with an estimated 10-year ASCVD predicted risk of 5% to 20% in China. Physical activity (PA) is effective in preventing ASCVDs, yet fewer than 60% of older adults meet WHO PA recommendations. Prior health education programmes have shown suboptimal attendance rates (e.g., 33% of participants attending 90% of sessions; per-session exercise class attendance as low as 60%) and inconclusive between-group effects on PA, blood pressure, BMI, weight, and waist circumference. A key gap is the lack of programmes designed to enhance exercise self-efficacy, which is a known core motivator of PA in older adults. This protocol describes a randomised controlled trial (RCT) testing an integrated exercise and cardiovascular health education programme grounded in Bandura's self-efficacy theory, which incorporates four sources of self-efficacy: mastery experience, vicarious experience, verbal persuasion, and emotional states.
**Methods:** This is a parallel two-arm RCT with a pretest-posttest design, conducted in urban elderly community centres in the Guangdong-Hong Kong-Macao Greater Bay Area. A total of 190 Chinese community-dwelling adults aged 60 years or older (95 per group) will be recruited, based on a sample size calculation using G*Power (effect size 0.45 from a meta-analysis by Conn et al., power 0.80, α = 0.05, two-tailed test, with 20% attrition). Inclusion criteria: aged ≥60; at least one ASCVD risk factor (current smoking, excessive alcohol consumption, diagnosed hypertension/diabetes mellitus/hyperlipidaemia, BMI ≥ 25 kg/m², family history of coronary heart disease/stroke, or anticoagulant use for ASCVD prevention); passing a cardiovascular fitness test; owning a mobile phone able to read text messages; able to read Chinese and communicate in Cantonese. Exclusion criteria: visual/hearing/cognitive/psychiatric/musculoskeletal impairment; prior attendance at any cardiovascular education programme; medical diagnosis of coronary heart disease or stroke. Eligible participants will be randomised 1:1 via computer-generated sequences concealed in sequentially numbered, opaque, sealed envelopes. The experimental group receives a 12-week programme: a 60-minute group health education talk (Week 1) covering ASCVD risk factors and PA, a booklet, a lecture video, a tailor-made exercise video (moderate-intensity exercises integrating balance, aerobic, and muscle-strengthening activities using a chair and towel, to be performed twice daily for 25 minutes), a portable video player, an exercise log, and 36 one-way SMS booster messages (3 per week for 12 weeks) with content derived from self-efficacy theory. The control group receives a placebo 60-minute talk on basic health issues, a lecture video, a portable video player, and a governmental leaflet, with SMS reminders only for data collection. Outcomes are measured at baseline, Week 12, Week 24, and Week 36. The primary outcome is PA level at Week 24 measured by the Chinese version of the Physical Activity Scale for the Elderly (PASE-C). Secondary outcomes include PA level (IPAQ-C), exercise self-efficacy (SEE-C), blood pressure (sitting, automatic monitor, average of two measurements after 5-minute rest with 1-minute interval), fasting blood glucose, fasting blood lipids (LDL, HDL, triglycerides via finger-prick auto-analyser after 8-hour fast), weight (to nearest 0.1 kg), height (to nearest 1 cm), BMI, waist circumference (average of two measurements to nearest 0.1 cm), and cardiac endurance (Two-Minute Walk Test). Data will be analysed using Generalised Estimating Equations (GEE) with identity link for continuous outcomes and cumulative logit link for ordinal outcomes, adjusting for age, gender, hypertension, and centre as covariates. Intention-to-treat analysis will be used, with missing data handled via Little's MCAR test, weighted GEE for MAR, and controlled imputation for MNAR.
**Clinical Implications:** If the integrated, self-efficacy-based programme proves effective in improving PA levels and ASCVD risk profiles among community-dwelling older adults, it could provide healthcare professionals with a more effective teaching strategy compared to traditional lecture-based approaches. The programme is designed to be scalable and could be applied to other health education programmes for older adults, potentially reducing the long-term healthcare burden of ASCVDs. Limitations include restriction to Cantonese/Chinese speakers, potential for higher absence rates at follow-up (mitigated by reminder messages), and risk of contamination between groups within the same centre.