Lower extremity functioning will be assessed using the Short Physical Performance Battery (SPPB). The scores range from 0 to 12 (higher score indicating better performance) and are based on performance on three tasks including gait speed, chair stand, and static standing balance with different three standing positions.

The 30-second Chair Stand Test will be used to assess lower body strength and endurance, particularly of the hip and thigh muscles important for daily mobility and fall prevention. Using a standard armless chair about 43-45 cm high, participants will sit with feet flat and arms crossed over the chest. At the signal "go," they will repeatedly stand to full extension and sit back down as many times as possible within 30 seconds without using their arms. The score will be the total number of full stands completed before time expires; partial rises will not be counted. Higher counts will indicate greater lower limb strength and functional capacity.

Executive function will be assessed using Trail-Making Test (TMT) Part B and the Controlled Oral Word Association test (COWAT). For TMT Part B, participants will be instructed to draw a line to connect consecutive numbers in numerical order and letters in alphabetical order in an alternating sequence (e.g., 1-ก-2-ข-3-ค) as quickly and correctly as possible. For the COWAT, participants will have to generate as many words as possible in a 60s timeframe starting with F, then A, then S. The score will be calculated by the number of words correctly iterated. Attention and processing speed will be assessed using Trail-Making Test (TMT) Part A and the digit symbol Substitution. For TMT Part A, participants will be instructed to draw a line to connect consecutive numbers in numerical order as quickly and correctly as possible (e.g., 1-2-3).

Semantic fluency will be assessed using the animals naming test. Participants will be asked to generate as many animals as they can within 60 second. The total score will be calculated from the maximum number of animals listed.

The modified switching verbal fluency test (mSVF) will be a cognitive flexibility test. In this test, participants will be required to alternately present words from two categories, fruits and animals, as many as possible within a 1-minute period. The researcher will record the correct word count for each category.

For the digit symbol substitution, participants will be instructed to match symbols to numbers according to a key located on the top of the paper test. Participants will have to copy the symbol into spaces below a row of numbers. The score will be calculated by the total number of correct symbols within the allowed time, usually 90 to 120 seconds.

Short-term auditory memory and working memory will be measured using the two parts of the Digit Span test: Digits Forward and Digits Backward. These will be administered separately. The digits will be presented at a rate of one per second. In Digits Forward (DSF), the patient is required to repeat the digits in the same order as presented. In Digits Backward (DSB), the patient is required to repeat the digits in reverse order. Participants will listen to a series of numbers presented at 1 number per second and repeat them either in the same order (DSF) or in reverse (DSB). For example, after hearing "6, 9, 4, 7," participants will repeat "6, 9, 4, 7" (DSF) or "7, 4, 9, 6" (DSB). Numeric sets will range from 2 to 10 digits. Each set will be tested three times. If participants correctly recall the sequence at least twice, they will pass that set. Failure to do so will result in stopping the test.

Fear of falling will be assessed using short Falls Efficacy Scale international (Short FES-I). The Short FES-I version which is an interview-based questionnaire contains 7 activities of daily living. The level of concern about falling through a combination of pictures and matching short phrases is scored on a 4-point scale (1 = not at all concerned to 4 = very concerned). The total score ranges from 7 to 28.

Symptoms of depression will be assessed using Thai Geriatric Depression Scale (TGDS). The short form of TGDS is a 15-item self-report questionnaire that inquiries about depressive emotion in daily situations experienced in the past week. Participants will rate each item as yes or no, scores range from 0 to 15, with higher scores indicating greater symptom severity.

Anxiety symptoms will be assessed using Goldberg Anxiety Scale (GAS). The GAS consists of 9-item for self-rating of anxiety experienced in the past month which includes affective and somatic symptoms of anxiety. The score will be rated as yes (1) or no (0) answers with a total score ranging from 0 to 9 which higher scores substantially increase the probability of a significant anxiety disorder.

Participants will perform electroencephalogram (EEG) recordings during resting-state. In the resting-state, each participant will seat in a comfortable chair in a relaxed position during the EEG measurement, which consists of 5-minute session for eyes opened and eyes closed conditions. The EEG signals will be recorded during resting state using an eegoTMmylab ANT Neuro (32-electrodes EEG cap). The EEG recording will use a sampling rate of 512 Hz and a notch filter of 50 Hz. A software filter will set to bandpass with a low pass of 0.3 Hz and a high pass of 100 Hz. The impedance of the electrode-skin interface will keep below 20kΩ, as recommended in prior scholarship. The EEG instrument consisted of 32 channels at the recording of position includes Fp1, Fpz, Fp2, F7, F3, Fz, F4, F8, FC5, FC1, FC2, FC6, T7, T8, C3, Cz, C4, CP5, CP1, CP2,CP6, P3, P7, Pz, P4, P8, POz, O1, Oz, O2, M1, M2, CPz (reference electrode), and AFz (ground electrode).

Participants will perform the event-related potentials (ERPs) recordings during Go/No-go task (using 4 images) in response to visual stimuli. Participants will have the brain activity measured with an electroencephalography (EEG) cap while performing an image-viewing task. The cap will record the brain signals as participants view images and respond by pressing a pedal with their's dominant foot. Participants will complete practice pedal presses to become familiar with the response before the actual test. When participants see image "(1)" or "(3)" they should press the pedal; when they see image "(2)" or "(4)" they should not press the pedal. The picture stimuli will present in random order during each trial, and each trial lasted 2-minutes. Participants will give a 5-minute rest between trials, and the duration of the two experiments was 40 minutes.

The Physical Activity Scale for the Elderly (PASE) Thai-version evaluates physical activity through 10 questions covering walking, exercise, household chores, and work. Participants will report activity type, frequency, and duration over the past week. Scores are calculated by multiplying activity frequency and duration by assigned weights. Activities like chores and work are scored based on average daily hours, adjusted by weights; sedentary tasks score 0. The total score, ranging from 0 to 400, excludes sitting activities.

The participants' QOL will also be evaluated by using the WHOQOL-BREF-Thai questionnaire that can be assessed by self-report. In situations that the participants cannot read, the assessor will read for them, and they will have to choose the answer by themselves. The WHOQOL-BREF questionnaire has two types of questions: perceived objective and self-report subjective, and it includes four components of well-being: physical, psychological, social, and environmental. Each item is scored from 1-5. This Thai version has a good internal consistency with Cronbach's alpha 0.84. The higher score indicates better QOL.

Each participant will be given weekly fall diaries to mark any falls during the study period. A fall is defined as "an unexpected event in which the person comes to rest on the ground, floor, or lower level". If fall data is not received, telephone calls will be used to obtain fall data.

At the completion of the Smart±step training (3 months and 6-months), participants will rate the usability of the Smart±step training using the System Usability Scale (SUS): SUS scores of 50-70 are acceptable, 71-85 are good to excellent, >85 are excellent usability, and <50 are considered unacceptable.

Enjoyment during engaging in the Smart±Step training exercise will assess using Physical Activity Enjoyment Scale (PACES) Enjoyment Scale (PACES). The PACES is an 8-item scale questionnaire that measures the level of enjoyment using a 7-point Likert scale ranging from 1 (strongly disagree) to 7 (strongly agree). The scores for enjoyment were obtained through the sum of PACES scores. A higher score indicates a greater level of enjoyment.

All participants will be instructed to complete a logbook immediately after each exercise session to ensure data accuracy. Adherence to the intervention will be calculated as the percentage of Smart±Step sessions attended, using the formula: ((n/24 sessions) x 100). Any adverse events occurring during the study, such as injuries, falls, fatigue, or other exercise-related issues, will be documented. Furthermore, participants will be asked about their training experiences and any health issues at every follow-up point throughout the study. They will also be encouraged to contact the research team at any time with questions or concerns.