A 6-month programs led by trained young-old exercise coaches consisting of structured training with 5 progressive levels of intensity, with protocols for implementation in a home surrounding and community center settings. During the 6-month program, group practice and home visit (individual) (45 mins each) are delivered in a tapering schedule:

• 1st month: group practice (1 time/week), home visits (2 times/week)
• 2nd month: group practice (1 time/week), home visit (1 time/week), phone call (1 time/week)
• 3rd month: group practice (1 time/week), phone calls (2 times/week)
• 4th month: phone calls (2 times/week)
• 5th month: phone calls (1 time/week)
• 6th month: weaning period

A 6-month program led by retired nurses covering topics including nutrition, sleep, medication, cognition, and exercising. During the 6-month program, group talks and individual consultation (45 mins each) are delivered in a tapering schedule:

• 1st month: group talk (1 time/week), individual consultation (2 times/week)
• 2nd month: group talk (1 time/week), individual consultation (1 time/week), phone call (1 time/week)
• 3rd month: group talk (1 time/week), phone calls (2 times/week)
• 4th month: phone calls (2 times/week)
• 5th month: phone calls (1 time/week)
• 6th month: weaning period

Change in quality of life measured by World Health Organization Quality of Life - Older Adult Module (WHOQoL-OLD) at baseline, 6 months, 12 months and 18 months. It has a range of scores from 24 to 120. Higher scores indicate better quality of life, lower scores indicate poor quality of life.

Change in comprehensive frailty status measured by the 32-item Frailty Index (32-FI) at baseline, 6 months, 12 months and 18 months. The index is calculated by the sum score divided by the total number of valid responses, ranging from 0 to 1. Frailty status is defined as: robust (FI ≤ 0.08), prefrail (0.08 < FI < 0.25), and frail (FI ≥ 0.25).

Change in pain severity measured by Face Pain Scale - Revised at baseline, 6 months, 12 months and 18 months. It has a range of scores from 0 to 10, with 0 representing no pain, 10 representing very much pain.

Change in physical activity measured by Physical Activity Scale for the Elderly (PASE) at baseline, 6 months, 12 months and 18 months. It has a range of scores from 0 to 361, with higher scores indicating higher physical activity level and lower scores indicating lower physical activity level.

Change in activities of daily living measured by Modified Barthel Index at baseline, 6 months, 12 months and 18 months. It has a range of scores from 0 to 100, with higher scores indicating independence and lower scores indicating dependence.

Change in instrumental activities of daily living measured by Lawton Instrumental Activities of Daily Living at baseline, 6 months, 12 months and 18 months. It has a range of scores from 0 to 18, with higher scores indicating independence and lower scores indicating dependence.

Change in social network measured by Lubben Social Network Scale at baseline, 6 months, 12 months and 18 months. It has a range of scores from 0 to 50 (scores <20 are classified as isolated; 21-25 as high risk for isolation; 26-30 as moderate risk for isolation; ≥ 31 as low risk for isolation).

Change in sleep quality measured by Pittsburgh Sleep Quality Index at baseline, 6 months, 12 months and 18 months. It has a range of scores from 0 to 21, with higher scores indicating poor sleep quality and lower scores indicating better sleep quality.

Change in nutrition status measured by Mini Nutritional Assessment-Short Form at baseline, 6 months, 12 months and 18 months. It has a range of scores from 0 to 30 (scores of 24-30 are classified as normal nutritional status; 17-23.5 as at risk of malnutrition; <17 as malnourished).

Change in depressive symptoms measured by Patient Health Questionnaire - 9 (PHQ-9) at baseline, 6 months, 12 months and 18 months. It has a range of scores from 0 to 27 (scores of 5-9 are classified as mild depression; 10-14 as moderate depression; 15-19 as moderately severe depression; ≥ 20 as severe depression)

Change in extent of mobility measured by the Life Space Questionnaire at baseline, 6 months, 12 months and 18 months. It has a range of scores from 0 to 9, reflecting the number of zones a person has moved in irrespective of the frequency and independence of these movements.

Change in verbal fluency was measured by the Verbal Fluency Test at baseline, 6 months, 12 months and 18 months. Performance is defined by the number of items in a category that can be verbally listed in 60 seconds. It has a range of scores from 0 to 20, with higher scores indicating higher verbal fluency and lower scores indicating lower verbal fluency.

Change in cognitive performance measured by Digit Symbol Substitution Test at baseline, 6 months, 12 months and 18 months. Performance is defined by the number of correct symbols substitution in 90 seconds. It has a range of scores from 0 to 93, with higher scores indicating better cognitive performance and lower scores indicating poor cognitive performance.

Change in logical memory was measured by the Logical Memory Test at baseline, 6 months, 12 months and 18 months. Performance is defined as the number of correct word items recalled. It has a range of scores from 0 to 23, with higher scores indicating better logical memory and lower scores indicating poor logical memory.

Change in digit span measured by the Digit Span Test at baseline, 6 months, 12 months and 18 months. The sequence and span scores have a range from 0 to 8 for forward subsets, and the sequence and span scores have a range from 0 to 7 for backward subsets. Higher scores indicating better cognitive performance and lower scores indicating poor cognitive performance.

Change in health literacy measured by Chinese Health Literacy for Chronic Care at baseline, 6 months, 12 months and 18 months. It has a range of scores from 0 to 48, and the cut-off score is 36 (≥ 36 indicates "adequate health literacy").

Change in functional muscular fitness measured by 30-second Chair Sit-to-stand Test at baseline and 6 months (outcome in frail subgroup only). The score is the number of stands a person can complete in 30 seconds, with higher scores indicating better functional muscular fitness and lower scores indicating poor functional muscular fitness.

Change in upper and lower body strength measured by 3-repetition Maximum (3-RM) Test using Keiser pneumatic variable-resistance machines at baseline and 6 months (outcome in frail subgroup only). The score is defined as the maximum weight a person can lift for 3 repetitions.

Change in cardiovascular fitness measured by Ergometers and MedGrapics Ultima CardiO2 Gas Exchange System at baseline and 6 months (outcome in frail subgroup only).

Change in balance measured by Multifunctional force-measuring plate at baseline and 6 months (outcome in frail subgroup only).

Change in flexibility measured by Sit and Reach Flexibility Test at baseline and 6 months (outcome in frail subgroup only). The score is the recorded distance a person can reach forward by the hand with a seated position.