The participants of HF will receive a total of 36 training sessions, and each session will contain 90-120 minutes of training.

The participants of LF will receive a total of 12 training sessions, and each session will contain 90-120 minutes of training.

The programs are based on dual-task trainings which contain cognitive training and exercise simultaneously. For physical exercise, we will design the programs that involve balance or strength training components in the aerobic exercises. In terms of cognitive training, we will design self-made teaching aids and board games to train different domains of cognitive functions. We plan to assess the participants before and after the intervention programs. We expect that elders receiving dual-task training will improve on outcome measures, and the group with more frequency will have better performance. The results of the study will provide evidence of interventions for elderly with cognitive decline, thereby reducing the burden on their caregivers and the cost of medical resource.

The Montreal Cognitive Assessment (MoCA) was designed as a rapid screening instrument for mild cognitive dysfunction. It assesses different cognitive domains: attention and concentration, executive functions, memory, language, visuoconstructional skills, conceptual thinking, calculations, and orientation. Time to administer the MoCA is approximately 10 minutes. The total possible score is 30 points; a score of 26 or above is considered normal.

The Mini-Mental State Examination (MMSE) is the most commonly administered psychometric screening assessment of cognitive functioning. The MMSE is used to screen patients for cognitive impairment, track changes in cognitive functioning over time, and often to assess the effects of therapeutic agents on cognitive function. The total score of MMSE ranged from 0 to 30. Higher values represent a better cognitive functioning.

The Stroop test will be used to assess the processing speed, inhibition, set-shifting, and selective attention abilities. The participants will be tested under 2 conditions: congruent and incongruent conditions. In the congruent condition, the color ink of a word is consistent with the written color name; while the color ink differs from the written color name under the incongruent condition.

The TUG test will be used to assess the mobility and dynamic balance ability. The participants will be required to stand up from a chair, walk 3 meters, turn around, then walk back to the chair, and sit down. The time to complete the TUG test has been shown to be a good indicator to detect potential fallers and frail elderly (Podsiadlo & Richardson, 1991). The test-retest reliability of TUG on individuals with cognitive impairment was excellent.

The social participation level will be assessed with the Community Integration Questionnaire (CIQ).It contains 15 items to evaluate the degree of integration into each of the three area of family, social network, and productive activities. The total scores range from 0 to 29 with larger numbers indicating better integration.